ATA 24 Electrical Power PDF - Bombardier DHC 8-400

BOMBARDIER DHC 8-400 (PWC PW150) ATA 24 - ELECTRICAL POWER TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION PURPOSE The Electrical Power Generation and Distributi...

BOMBARDIER DHC 8-400 (PWC PW150) ATA 24 - ELECTRICAL POWER TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY B1/B2 MAINTENANCE TRAINING MANUAL Issue 6 - January 2023 Page 1 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION PURPOSE The Electrical Power Generation and Distribution System (EPGDS), supplies electrical energy to all electrical equipment through an AC Variable Frequency System and Main 28V DC Generation System. The EPGDS does energy conversion, distribution, storage, control, protection, monitoring, and indication. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 2 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - EPGDS SIMPLIFIED BLOCK DIAGRAM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 3 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION It reconfigures when an electrical power source or bus malfunction, by the automatic closing and opening of bus tie contactors. GENERAL DESCRIPTION The EPGDS has these sub-systems: • • • • • • • • Alternating current variable frequency Main 28V DC generation Battery Auxiliary Power Unit (APU) 28V DC External AC ground power External DC ground power AC electrical load distribution DC electrical load distribution The AC variable frequency generators make 115V AC three phase electrical power for AC systems that are not frequency sensitive, such as de-icing heaters, fuel auxiliary pumps, the Standby Power Unit (SPU) hydraulic pump and the galleys. They also energize the Transformer Rectifier Units (TRU), which are part of the Main 28V DC Generation System to supply 28V DC. The Main 28V DC Generation System is energized by theses sources: • • • • Two engine driven starter/generators Two Transformer Rectifier Units (TRU) Three NiCad batteries Auxiliary Power Unit (APU) The EPGDS has connections AC for and DC external power while on the ground. NOTE: The AC external power source does not supply electrical power for engine starting. The power is distributed by an electrical bus system. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 4 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - EPGDS BLOCK DIAGRAM TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 5 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION The contactors to connect the main and auxiliary batteries are located in the DC Contactor Box (DCCB) and the contactors that control the standby battery operation are located in the Standby Battery Contactor Box (SBCB). BATTERY SYSTEM PURPOSE The battery system supplies aircraft engine start power, emergency 28V DC electrical power to the aircraft DC essential buses and to the No.3 Standby Hydraulic Pump. GENERAL DESCRIPTION The battery power system of the aircraft has three batteries and switching devices to supply electrical power to the essential buses during emergency flight conditions. The main, auxiliary, and standby batteries are connected to the main feeder buses to receive a charging current. The main and the auxiliary batteries also connected to the main feeder buses to supply electrical power to start the engines. During an engine start condition, the standby battery is isolated from the main feeder bus, but stays connected to the essential buses to maintain a minimum voltage level on the essential bus. The standby battery has a related battery power bus in the right DC circuit breaker panel that is energized at all times. The auxiliary and main batteries have a related battery power bus in the left DC circuit breaker panel that is energized when the AUX BATT or MAIN BATT toggle switch is set to on. The Engine and System Integrated Display (ESID) system shows main 28V DC generation system electrical indications. The Battery system has these components: • • • • • • Battery and Box, Main Vent and Drains, Main Battery Battery and Box, Auxiliary Vent and Drains, Auxiliary Battery Battery and Box, Standby Vent and Drains, Standby Battery TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 6 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - BATTERY SYSTEM BLOCK DIAGRAM, CONTROLS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 7 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM GENERAL DESCRIPTION CONTINUED The Multi-Function Display (MFD) electrical system page and the caution and warning lights system show battery system indications. The Electrical Power Control Unit (EPCU) supplies indication data through the two Input/Output Processors (IOP1, IOP2) located in the Integrated Flight Cabinets (IFC) to the Electronic Instruments System (EIS). TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 8 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - BATTERY SYSTEM BLOCK DIAGRAM, INDICATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 9 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION disconnect the standby, auxiliary and main batteries from their related main feeder bus. The essential distribution buses stay energized by the standby, auxiliary and main batteries. BATTERY SYSTEM The emergency mode is caused by these conditions: DETAILED DESCRIPTION The BATTERY MASTER toggle switch is set to the ON position to close battery contactors K3, K4 and K24 and connect the three batteries to the two essential buses. The left essential bus is connected through isolation diode CR21 to the battery power bus that is in the left circuit breaker panel. Contactor K3, K4 and K24 are controlled directly by the BATTERY MASTER toggle switch. Their operation is independent of the Electrical Power Control Unit (EPCU). The essential buses energize the EPCU. The BATTERY MASTER toggle switch must be set to the ON position before the battery toggle switch selections are made to connect the batteries to the main feeder buses. Each battery is connected to the main feeder buses to receive a charging current when a related battery toggle switch and the EPCU allows the connection. A STBY BATT toggle switch selection, will allow the standby battery to be charged by the left main feeder bus through contactor K25. An AUX BATT toggle switch selection will cause the auxiliary battery to connect to the left main feeder bus through contactor K7. The hot auxiliary battery bus is connected through isolation diode CR21 to the battery power bus that is in the left circuit breaker panel. A MAIN BATT toggle switch selection will cause the main battery to connect to the right main feeder bus through contactor K8. The hot main battery bus is connected through isolation diode CR20 to the battery power bus that is in the left circuit breaker panel. • • • Electrical power is not available from the two DC starter/generators Electrical power is not available from one or two TRU The aircraft is airborne If a start attempt is made during the emergency condition, the batteries will automatically reconnect to the main feeder buses for the duration of the start sequence. The STBY BATT, AUX BATT, and MAIN BATT toggle switches energize their contactors through the flight compartment contactor when energized by a BATTERY MASTER toggle switch selection and usually closed contacts of a relay in the EPCU. The relay in the EPCU is controlled by logic. In some conditions, the relays in the EPCU open to open the contactor. The batteries disconnect from the main feeder buses by these conditions: • • APU or DC GCU senses an over current condition When charging is not allowed. A manual STBY BATT toggle switch selection will connect the standby battery to the left main feeder bus by closing contactor K25. The EPCU causes contactor K25 to close when an emergency condition is not sensed. NOTE: Contactor K25 is energized during the engine start mode. Diode CR6 prevents the standby battery from energizing the DC starter/generators during the engine start mode. During an emergency condition, the batteries are the electrical power sources for the main 28V DC generation system. Contactors K25, K7 and K8 will open to TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 10 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - BATTERY SYSTEM BLOCK DIAGRAM, OPERATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 11 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM DETAILED DESCRIPTION CONTINUED The batteries are charged while they are connected to the main feeder buses. The charging sources are either DC starter/generators, the DC external power, or the aircraft Transformer Rectifier Units (TRU). A constant potential voltage is supplied to the battery terminals to charge the batteries. When the DC starter/generators are used to charge the batteries, a regulated 28.5V DC output is supplied to the batteries. When the batteries are charged from a DC external power source or AC external power source through the TRU, the charging current and temperature of the batteries must be visually monitored. The battery current shunts supply standby, auxiliary, and main battery output current data to the EPCU for EIS indication. The negative terminal of each battery is connected through separate current shunts to airframe ground potential. The battery current shunts are located near the batteries. The batteries have two independent internal sensors that sense battery temperature. A thermal sensor supplies battery temperature data to the EPCU for EIS indications, and a bimetallic temperature switch supplies temperature exceedance data to the caution and warning system for warning indications. The internal sensor wires are routed through a circular connector which is attached to the battery case. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 12 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - BATTERY SYSTEM BLOCK DIAGRAM, OPERATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 13 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION The capacity is usually less than the rated value when the discharge current is more than the nominal value. BATTERY SYSTEM NOTE: MAIN AND AUXILIARY BATTERIES The left lower nose compartment door must be opened to access the main and auxiliary batteries. The main battery is located forward of the auxiliary battery. The batteries are secured to the airframe in the nose compartment with tabs that are part of the battery case cover. The case is a steel box with a removable cover to give access for inspection. It also has a vent port that attaches to a tube that routes the gas overboard through a containment vessel. The voltage at the battery terminals cannot be used as an indication of the battery state of charge. The battery has nickel and cadmium (NiCad) plates with potassium hydroxide electrolyte. The NiCad battery has relatively constant voltage for most of the discharge condition. A main power positive and negative electrical connection to the battery terminals is made with a power plug connector attached to the case. The batteries have two independent internal sensors that sense battery temperature. The main and auxiliary batteries are 40 A hour batteries with an assembly of individual cells contained in a steel case. Each cell is connected in series to make 24V DC at the terminals. Solid copper bus bars are used to connect the cells. They weigh 76.5 lb/34.7 kg and are 10.25 in./260.4 mm wide, 10.5 in./ 266.7 mm long and 9.7 in./246.4 mm high. A Resistive Temperature Device (RTD) thermal sensor is used to measure the battery temperature for an EIS indication and a bimetallic temperature switch is used to sense a temperature exceedance for a warning indication. The internal sensor wires are routed through a circular connector attached to the battery case. The main and auxiliary batteries are self contained power sources that operate in the charge and discharge modes. The left lower nose compartment door must be opened to access the main and auxiliary batteries. The auxiliary battery is located aft of the main battery. It is secured to the airframe in the nose compartment with tabs that are part of the battery case cover. The main 28V DC generation system supplies electrical power to the battery during the charge mode. The amount of charge current is determined by the state of charge and the internal resistance of the battery. After a long discharge period, the initial charge current can peak at 200 A. The current rapidly decreases as the battery starts to charge. During the discharge mode, the battery supplies electrical power. The battery output voltage decreases as the current load increases. The 40 A hour batteries have a rated discharge of 40 A for one hour. The discharge rate is not linear. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 14 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN BATTERY LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 15 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - AUXILIARY BATTERY LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 16 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN AND AUXILIARY BATTERY LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 17 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM BATTERY CONTAINMENT VESSEL The left lower nose compartment door must be opened to access the containment system. It is secured to the battery shelf with three mounting screws. The overflow containment system protects the aircraft structure and other parts from the corrosive battery gases and fluid. Each battery has a vent port that attaches to a tube to route its gases through a containment vessel overboard. The electrolyte in the battery is potassium hydroxide and water. The containment system has a bottle with a boric acid and water wetted sponge to neutralize the battery electrolyte. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 18 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - BATTERY CONTAINMENT VESSEL LOCATOR, FORWARD TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 19 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION NOTE: BATTERY SYSTEM The voltage at the battery terminals cannot be used as an indication of the battery state of charge. STANDBY BATTERY The left upper nose compartment door must be opened to access the standby battery. The battery is secured to the airframe in the nose compartment with tabs that are part of the battery case cover. The case is a steel box with a removable cover to give access for inspection. It also has a vent port that attaches to a tube that route the gases overboard through a containment vessel. The battery is a 17 or 40 A hour battery with an assembly of individual cells contained in a steel case. Each cell is connected in series to make 24V DC at the terminals. Solid copper bus bars are used to connect the cells. The battery has nickel and cadmium (NiCad) plates with potassium hydroxide electrolyte. The NiCad battery has relatively constant voltage for most of the discharge condition. A main power positive and negative electrical connection to the battery terminals is made with a power plug connector attached to the case. The battery has two independent internal sensors that sense battery temperature. A Resistive Temperature Device (RTD) thermal sensor is used to measure the battery temperature for an EIS indication and a bimetallic temperature switch is used to sense a temperature exceedance for a warning indication. The internal sensor wires are routed through a circular connector attached to the battery case. The 17 ampere hour standby battery weighs 38.5 lb/17.46 kg. It is 7.7 in./195.6 mm wide, 8.5 in/215.9 mm long and 9.75 in./247.7 mm high. The Standby Battery is a self contained power source that operates in the charge and discharge modes. The main 28V DC generation system supplies electrical power to the battery during the charge mode. The amount of charge current is determined by the state of charge and the internal resistance of the battery. After a long discharge period, the initial charge current can peak at 200 A. The current rapidly decreases as the battery starts to charge. During the discharge mode, the battery supplies electrical power. The battery output voltage decreases as the current load increases. The 17 A hour batteries have a rated discharge of 17 A for one hour. The discharge rate is not linear. The capacity is usually less than the rated value when the discharge current is more than the nominal value. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 20 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - STANDBY BATTERY LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 21 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM CONTROLS AND INDICATIONS The battery toggle switch located on the DC control panel is set to BATTERY MASTER position to let the standby, auxiliary and main batteries energize the essential buses if no other DC power source is available. The battery toggle switches are set to STBY BATT, AUX BATT, and MAIN BATT positions to let the standby, auxiliary and main batteries connect to the main feeder buses to receive a charging current. NOTE: The BATTERY MASTER, AUX BATT, or MAIN BATT toggle switch is set to on to energize the battery power bus in the left DC circuit breaker panel. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 22 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - BATTERY SYSTEM, DC CONTROL PANEL TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 23 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM CONTROLS AND INDICATIONS CONTINUED The MFD1 and MFD2 reversion switches located on the ESID Control Panel (ESCP) are used to select the electrical page on the multi-functional displays. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 24 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - EIS, ELECTRICAL SYSTEM PAGE SELECTION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 25 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM CONTROLS AND INDICATIONS CONTINUED The Multi-Function Display (MFD) electrical system page shows these battery system indications: • • Load Temperature The battery indication has a BATT title in white letters. The indication has MAIN, AUX and STBY titles in white fonts to show the load and temperature of the main, auxiliary and standby batteries. BATTERY LOAD INDICATION The battery load indication shows the battery load in white numbers. The numbers show the battery output load as a percentage of the total rated output. A (+) symbol before the numbers is used to show an overload condition of the battery. The symbol is out of view when the load is less than 100 %. A (-) symbol shows a discharge condition. BATTERY TEMPERATURE INDICATION The battery temperature indication shows the battery temperature in degrees Celsius in white numbers. The indication changes to yellow when temperature is more than 50°C and less than 65°C. If the temperature is more than 65°C, the indication will change to red. NOTE: The Resistive Thermal Device (RTD) supplies temperature data through the EPCU and FDPS to the EIS. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 26 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - EIS, BATTERY SYSTEM INDICATIONS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 27 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM CONTROLS AND INDICATIONS CONTINUED When the voltage or load data malfunctions, the digits are replaced by white dashes. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 28 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - EIS, BATTERY SYSTEM MALFUNCTION INDICATIONS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 29 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM CONTROLS AND INDICATIONS CONTINUED The battery system malfunctions are shown with these caution lights: • • • STBY BATTERY AUX BATTERY MAIN BATTERY STBY BATTERY, AUX BATTERY, MAIN BATTERY CAUTION LTS The STBY BATTERY, AUX BATTERY or MAIN BATTERY caution lights come on to show that the battery is not connected to its main feeder bus for charging. The caution lights receive their signals from the related contactor K25, K7 and K8. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 30 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - CAUTION AND WARNING PANEL, BATTERY SYSTEM CAUTION INDICATIONS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 31 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM CONTROLS AND INDICATIONS CONTINUED The battery system malfunctions are shown with these warning lights: • • • STBY BATT HOT AUX BATT HOT MAIN BATT HOT STBY BATT HOT, AUX BATT HOT, MAIN BATT HOT WARNING LTS The STBY BATT HOT, AUX BATT HOT or MAIN BATT HOT warning lights come on to show that the battery temperature is more than 71°C. It goes out when the temperature is less than 63°C. The inputs to these warning lights come directly from the bi-metal temperature switch located in each battery. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 32 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - CAUTION AND WARNING PANEL, BATTERY SYSTEM WARNING INDICATIONS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 33 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION BATTERY SYSTEM INTERFACES The standby battery energizes the No.3 hydraulic Direct Current Motor Pump (DCMP) thorough a circuit breaker and contactor K23. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 34 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - STANDBY BATTERY SYSTEM SCHEMATIC TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 35 of 308 BOMBARDIER DHC 8-400 (PWC PW150) • • ELECTRICAL POWER GENERATION DC Current Transformers (DC CT) Current shunts MAIN 28V DC GENERATION SYSTEM PURPOSE The main 28V DC generation system makes and supplies 28V DC electrical power to the aircraft DC buses. GENERAL DESCRIPTION The main 28V DC generation system has two DC starter/generators, one on each engine, and two Transformer Rectifier Units (TRU) to supply electrical power independently to the left and right DC bus systems. When a DC starter/generator or TRU malfunctions, the main 28V DC generation system automatically connects its bus to another serviceable electrical source for continuous operation. A DC external power receptacle and control circuitry allows the system to be powered from an external power source while the aircraft is on the ground. Toggle switches located on the DC control panel in the flight compartment give manual control of the main 28V DC generation system. The Engine and System Integrated Display (ESID) system shows main 28V DC generation system electrical indications. The Main 28V DC Generation System has these units: • • • • • • • • DC Starter/Generators (GEN) DC Generator Control Units (DC GCU) Electrical Power Control Units (EPCU) DC control panel DC Transformer Rectifier Units (TRU) DC Contactor Boxes (DCCB) DCCB Contactors Standby Battery Contactor Box (SBCB) TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 36 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28V DC GENERATION SYSTEM BLOCK DIAGRAM, CONTROLS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 37 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM GENERAL DESCRIPTION CONTINUED The Multi-Function Display (MFD) electrical system page and the caution and warning lights system show main 28V DC generation system indications. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 38 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM BLOCK DIAGRAM, INDICATIONS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 39 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION The direct current (DC) system operates in these modes: • • • • • Normal Protection Fault Tolerant Emergency Diagnostics and Monitoring TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 40 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION The two DC generators supply 28V DC electrical power through the bus contactors, K1 and K2 to their related left or right main feeder bus. MAIN 28V DC GENERATION SYSTEM When the DC GCU senses a DC starter/generator malfunction, it will cause the bus contactor, K1 or K2 to open circuit the DC starter/generator source. DETAILED DESCRIPTION The DC current transformers at the negative (-) and positive (+) connections of the DC starter/generator supply current data to the DC GCU to control the DC starter/ generator output. Current shunts at the (-) connection of the DC starter/generators supply current data to the EPCU for indication. NORMAL MODE The DC electrical power from DC starter/generators and Transformer Rectifier Units (TRU) is distributed to the DC buses through a DC contactor box located in the nose compartment of the aircraft. The TRU electrical power is supplied to the DC secondary distribution buses in the flight compartment through the secondary feeder buses located in the DC contactor box. The contactor box contains the switching, protection, and measurement components. When the EPCU senses a TRU malfunction, it will cause the secondary feeder bus tie contactor, K22 to move to a cross-tie position to connect its secondary feeder bus to the other TRU. When the aircraft engines are operating with no external DC power connected, and the DC generator toggle switches located on the DC control are set to GEN 1 or GEN 2 positions, the DC generators are connected to their related main feeder buses for normal operation. The related DC GCU automatically disconnects its DC starter/ generator when it senses a DC starter/generator malfunction. Each DC starter/generator is turned by the engine accessory gearbox. The DC starter/generator is controlled by its related DC Generator Control Unit (GCU). Each DC GCU automatically controls the operation of its DC starter/generator by monitoring output voltage, current, and speed. After an engine start, the DC GCU regulates its generator output and controls the operation of its bus contactor K1 or K2. When the Electrical Power Control Unit (EPCU) senses a DC starter/generator malfunction, it will cause the main feeder bus tie contactor, K21 to move to a cross-tie position to connect its main feeder bus to the other DC starter/generator. When the main feeder bus tie toggle switch on the DC control panel is set to the MAIN BUS TIE position, the main feeder buses are manually connected together through main feeder bus tie contactor, K21. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY The DC electrical power is distributed to the DC distribution buses through a DC contactor box located in the nose compartment of the aircraft. The DC starter/generator electrical power is supplied to the main distribution buses in the flight compartment through the main feeder buses and the generator bus contactors, K1 and K2 located in the DC contactor box. The main distribution buses supply their related essential distribution buses through isolation diodes, CR3 and CR2. The isolation diodes make sure that the essential distribution buses cannot energize the main feeder buses. When electrical power is not available from the main feeder buses, the essential buses are energized by the standby, auxiliary, and main batteries through battery bus contactors K24, K3, and K4, and isolation diodes, CR8, CR5 and CR4. ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 41 of 308 BOMBARDIER DHC 8-400 (PWC PW150) NOTE: The left and right essential distribution buses are connected together through circuit breakers on each essential distribution bus. ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION NORMAL MODE CONTINUED When the DC GCU senses a DC starter/generator malfunction, it will cause bus contactor, K1 or K2 to open circuit the DC starter/generator. A fault signal is sent to the EPCU to cause the main bus tie contactor, K21 to connect the bus to the other DC starter/generator. The TRU electrical power is supplied to the secondary distribution buses in the flight compartment through the main feeder buses located in the DC contactor box. When the EPCU senses a TRU malfunction, it will cause its bus to connect to the other TRU through the secondary bus tie contactor, K22. The DC GCU sense their related DC starter/generators speed and voltage while the DC generator toggle switch is set to the DC GEN position. The DC GCU regulates its DC starter/generator voltage when the DC starter/generator speed and voltage are stable. The DC GCU controls the contactors to supply DC starter/generator power to the aircraft buses. The DC GCU also monitors the DC starter/generator current and controls its bus contactor. The EPCU automatically controls the main 28V DC generating system. Toggle switches in the flight compartment are used to control the main 28V DC generating system when the EPCU malfunctions. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 42 of 308 BOMBARDIER DHC 8-400 (PWC PW150) The main 28V DC generation system uses its DC GCU and EPCU to control the contactors for active protection so that a fault condition will not cause damage to the DC starter/generators and TRU. It uses these protective functions: • • • • • • ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION OVER VOLTAGE PROTECTION FUNCTION The protection functions in the main 28V DC generation system prevent damage to the DC starter/generators, TRU, or other related equipment if there is a malfunction or an overload condition. The main 28V DC generation system continuously monitors itself. When a fault is sensed, it isolated the effect of the fault from the remaining system to allow continued operation. The main V DC generation system protective functions are classified as passive protection and active protection. The main 28V DC generation system uses circuit breakers and fuses for passive protection so that a malfunction condition will not cause damage to the DC starter/ generator and TRU. The circuit breakers and fuses are protection devices that open circuit during excessive current flow. Unlike fuses, circuit breakers can be reset without having to be replaced. Circuit breakers in the DC contactor box are thermally compensated for an operating temperature range of -55°C to +71°C. Each circuit breaker current rating is dependent on the circuit that it protects. Fuses are used in the DC Contactor Box (DCCB) to protect the environment cooling system fan power, and the secondary bus cross-tie and contactor K22. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY Over voltage Over current Differential feeder protection Build-up ground fault Reverse current TRU under voltage detection When the voltage from a DC starter/generator is more than 32.5V DC, its DC GCU de-energizes the DC starter/generator and opens its related bus-tie contactor, K1 or K2. The EPCU connects its bus to the other DC starter/generator. This protection has an inverse time delay to make sure that the disconnect time is inversely proportional to the magnitude of the over voltage level. OVER CURRENT When the DC starter/generator interpole current is more than 800 A, the DC GCU supplies an over current signal to the EPCU. If the condition continues for more than 5 seconds, the EPCU sends a trip signal back to the related DC GCU for it to de-energize its DC starter/generator and open the related bus-tie contactor, K1 or K2. If the EPCU does not supply a trip signal to the DC GCU, the DC GCU de-energizes its DC starter/generator and opens its related bus-tie contactor, K1 or K2 after 7 seconds. The DC starter/generator will supply current for a maximum of 7 seconds to let the malfunction correct itself before disconnecting a DC starter/generator. ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 43 of 308 BOMBARDIER DHC 8-400 (PWC PW150) starter/generator and opens its related bus-tie contactor, K1 or K2. NOTE: A current limit signal is supplied to the DC GCU to limit its DC starter/ generator output current at 600 A during an opposite engine start condition and continues for 15 seconds to charge the batteries. The EPCU connects its bus to the other DC starter/generator. TRU UNDER VOLTAGE DETECTION If the TRU output voltage is less than 15V DC for more than 7 seconds, the TRU is considered defective. The EPCU will cause the secondary bus cross-tie contactor, K22 to connect the two secondary feeder buses together. FAULT TOLERANT ELECTRICAL POWER GENERATION The EPCU monitors the main 28V DC generation system symptoms for active malfunctions. If a malfunction is sensed, the EPCU will send the required signals to the DC bus system. MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION To protect the DC starter/generators, the main 28V DC generation system monitors itself for these faults: PROTECTION FUNCTION CONTINUED • • DIFFERENTIAL FEEDER PROTECTION Source Bus The current flow at - and + connections of the DC starter/generator is compared by the DC GCU differential current sensing circuits. When source or bus faults occur, the contactors open, and stay open until the EPCU is reset to prevent a reconnection to a fault condition. When the differential feeder current is more than 75 A, the DC GCU de-energizes its related DC starter/generator and opens its related bus-tie contactor, K1 or K2. The EPCU connects its bus to the other DC starter/generator. Time delay circuits in the DC GCU prevent usual transients caused by on and off switching of different loads to cause contactor operation. The BUS FAULT toggle switch on the DC control panel is set to the RESET position and then back to OFF position. DC current transformers at the - and + connections of the DC starter/generators supply DC current data to the DC GCU to control the DC starter/generator output. REVERSE CURRENT The DC GCU monitors for a reverse current condition. When a reverse current condition exceeds 10% of the rated load, the DC GCU de-energizes its related DC TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 44 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM OPERATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 45 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED SOURCE FAULT Each DC starter/generator usually supplies its own main feeder bus. When a DC starter/generator or DC GCU malfunctions, its related bus contactor, K1 or K2 will open to disconnect the DC starter/generator. Its related main feeder bus is energized by the other DC starter/generator. The EPCU will close the main feeder bus tie contactor, K21 to connect the left and right main feeder buses. In this reconfigured condition, all aircraft loads stay energized. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 46 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, DC STARTER/GENERATOR NO. 1 SOURCE FAULT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 47 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED SOURCE FAULT CONTINUED Each TRU energizes its own secondary feeder bus. The EPCU (Electrical Power Control Unit) checks the voltage on each secondary feeder bus. If the voltage is less than 15V DC for more than 7 seconds, the EPCU considers this to be a TRU malfunction. The EPCU will close the secondary bus tie contactor K22 to connect the right and left secondary buses. In this reconfigured condition, all aircraft loads stay energized. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 48 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, LEFT TRU SOURCE FAULT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 49 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED SOURCE FAULT CONTINUED When the two DC starter/generators or DC GCU malfunction their related bus contactors, K1 and K2 will open to disconnect the DC starter/generators. Their related main feeder bus will be energized by the related TRU. The EPCU will close the secondary/main feeder bus tie contactors, K5 and K6 to connect the buses. In this reconfigured condition, all aircraft loads stay energized. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 50 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, TWO DC STARTER/GENERATOR SOURCE FAULT PAGE 1 TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 51 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED SOURCE FAULT CONTINUED When the two TRU malfunction, their related secondary feeder bus will be energized by the related DC starter/generators. The EPCU will cause the secondary/main feeder bus tie contactors, K5 and K6 to connect the buses. In this reconfigured condition, all aircraft loads stay energized. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 52 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, TWO TRU SOURCE FAULT PAGE 1 TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 53 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED SOURCE FAULT CONTINUED When one DC starter/generator or DC GCU and one TRU malfunction, the related bus contactors, K1 or K2 will open to disconnect the DC starter/generator. Its related main feeder bus will be energized by the other DC starter/generator. The EPCU will cause the main feeder bus tie contactor, K21 to connect the buses. When a TRU malfunctions, its related secondary feeder bus will be energized by the other TRU. The EPCU will cause the secondary feeder bus tie contactor, K22 to connect the buses. In this reconfigured condition, all aircraft loads stay energized. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 54 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, DC STARTER/GENERATOR NO. 1 AND LEFT TRU SOURCE FAULT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 55 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED SOURCE FAULT CONTINUED When one DC starter/generator or DC GCU and two TRU malfunction, the related bus contactors, K1 or K2 will open to disconnect the DC starter/generator. Its related main feeder bus will be energized by the other DC starter/generator. The EPCU will cause the main feeder bus tie contactor, K21 to connect the buses. In this reconfigured condition, the secondary feeder buses are not energized. The main and essential aircraft loads stay energized. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 56 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, DC STARTER/GENERATOR NO. 1 AND TWO TRU SOURCE FAULT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 57 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED SOURCE FAULT CONTINUED When two DC starter/generators or DC GCU and two TRU malfunction, the related bus contactors, K1 or K2 will open to disconnect the DC starter/generator. The EPCU will cause the contactors, K7, K8, and K25 to disconnect the buses. In this reconfigured condition, the secondary feeder buses and main feeder buses are not energized. The essential aircraft loads stay energized. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 58 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, TWO DC STARTER/GENERATOR AND TWO TRU SOURCE FAULT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 59 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT The EPCU and the DC GCU sense bus faults and reconnect the main 28V DC generation system to make sure that the main feeder buses and secondary feeder buses are protected. The DC GCU uses the interpole voltage to sense an over-current condition of the DC starter/generator. The interpole series winding voltage in a DC starter/generator changes in relation to the load current of the generator. When the DC GCU senses an interpole voltage level that is more than twice the usual level, an over-current signal is sent to the EPCU. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 60 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, NORMAL OPERATION TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 61 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED With two DC starter/generators and two TRU available, the EPCU locks out the main feeder bus tie contactor, K21 one second after an over current condition is sensed. The secondary/main feeder bus tie contactors, K5 and K6 are locked out 100 ms later. If the over current condition continues for more than 5 seconds, the EPCU sends a trip signal to the DC GCU. The related bus contactor, K1 or K2 will open to disconnect the DC starter/generator. The EPCU also causes contactors, K25 and K7 or K8 to open to disconnect the standby and auxiliary batteries or the main battery from the main feeder bus. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 62 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, LEFT MAIN FEEDER BUS FAULT TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 63 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED When a DC starter/generator or DC GCU malfunctions, its related bus contactor, K1 or K2 will open and the main feeder bus tie contactor, K21 will close. In the example below, K1 is opened. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 64 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, DC STARTER/GENERATOR NO. 1 SOURCE FAULT PAGE 2 TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 65 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED Then, if an over current condition is sensed, the EPCU causes the main feeder bus tie contactor, K21 to open 1 second after an over current condition is sensed and contactors K5 and K6 100 ms later. If the over current condition stops after the main feeder buses are isolated, the bus fault is on the other main feeder bus. After 200 milliseconds the EPCU causes contactors, K25 and K7 to open to disconnect the standby and auxiliary batteries from the left main feeder bus. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 66 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, DC STARTER/GENERATOR NO. 1 SOURCE AND MAIN FEEDER ELECTRICAL POWER PAGE 2 TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 67 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED The EPCU causes the main feeder bus tie contactor, K21 to open 1 second after an over current condition is sensed and contactors K5 and K6 100 ms later The secondary/main feeder bus tie contactors, K5 and K6 are locked out 100 ms later. If the over current condition continues for more than 5 seconds, the EPCU sends a trip signal to the DC GCU. The related bus contactor, K2 will open to disconnect the DC starter/generator. The EPCU also senses an emergency condition and thus causes contactors, K25 and K7 or K8 to open to disconnect the standby and auxiliary batteries, and the main batteries from the left and right main feeder buses. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 68 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, DC STARTER/GENERATOR NO. 1 SOURCE AND MAIN FEEDER BUS FAULTS PAGE 1 TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 69 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED When a DC starter/generator or DC GCU malfunctions, its related bus contactor, K1 or K2 will open and the main feeder bus tie contactor, K21 will close. Then, an over current condition on a secondary feeder bus causes its related TRU circuit breaker to open. The EPCU then senses a TRU source fault and causes the secondary feeder bus tie contactor, K22 to close after 7 seconds. The high current condition causes the cross tie fuse that protects the other TRU from the effect of the bus fault to open. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 70 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, DC STARTER/GENERATOR NO. 1 SOURCE AND SECONDARY FEEDER BUS FAULTS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 71 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED When the two DC starter/generators or their DC GCU malfunction, their related bus contactors, K1 and K2 will open and the secondary/main feeder bus tie contactors, K5 and K6 will close. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 72 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, TWO DC STARTER/GENERATOR SOURCE FAULT PAGE 2 TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 73 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED Then, an over current condition on the left main feeder bus causes the TRU circuit breaker to open. The EPCU then senses a TRU source fault and causes the secondary feeder bus tie contactor, K22 to close after 7 seconds. The over current condition from the left main feeder bus causes the bus tie fuse to open. The right secondary and main feeder bus stays energized. NOTE: With no power to the left and right main distribution buses contactors, K25, K7, and K8 open to disconnect the standby and auxiliary batteries or the main battery from the main feeder bus. The standby, auxiliary, and main batteries will supply the essential distribution buses only. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 74 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, TWO DC STARTER/GENERATOR SOURCE AND MAIN FEEDER BUS FAULTS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 75 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED When two TRU malfunction, the secondary/main feeder bus tie contactors, K5 and K6 will close. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 76 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, TWO TRU SOURCE FAULT PAGE 2 TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 77 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED Then, an over current condition on a secondary feeder bus causes the TRU circuit breaker to open. After 1 second the EPCU causes the secondary/main feeder bus tie contactors, K5 and K6 to open to isolate the bus fault. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 78 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, TWO TRU SOURCE AND SECONDARY FEEDER BUS FAULTS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 79 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION PROTECTION FUNCTION CONTINUED BUS FAULT CONTINUED The main 28V DC generation system reconfiguration logic for source malfunctions is summarized in the table that follows. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 80 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - MAIN 28 VDC GENERATION SYSTEM, RECONFIGURATION LOGIC FOR SOURCE MALFUNCTIONS TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 81 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION MAIN 28V DC GENERATION SYSTEM DETAILED DESCRIPTION EMERGENCY MODE The main 28V DC generation system operates in the emergency mode when the two main feeder buses are disconnected from all DC power sources caused by source or bus fault conditions. Contactors, K25, K7, and K8 open to disconnect the standby and auxiliary batteries or the main battery from the main feeder bus. The standby, auxiliary, and main batteries will supply the essential distribution buses only. The emergency mode is caused by these conditions: • • • Electrical power is not available from the two DC starter/generators Electrical power is not available from one or two TRU, and The aircraft is airborne When a source or bus fault occurs, the main 28V DC generation system reconfigures, and stays reconfigured until the EPCU is reset by a main bus tie toggle switch selection. This feature is known as anti-cycling. DIAGNOSTICS AND MONITORING The electrical power system uses an on condition monitoring and diagnostic system. The system operational status is monitored by flight compartment indications, DC Generator Control Unit (GCU), EPCU functions. The DC GCU and EPCU give continuous monitoring of sub-system operation. The integrity of the protective functions in the DC GCU is checked by a Continuous Built In Test (CBIT) function in the EPCU so that other components are not affected by a defective test circuit. TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 82 of 308 BOMBARDIER DHC 8-400 (PWC PW150) INTENTIONALLY LEFT BLANK TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 83 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER GENERATION magnetic circuit for the starter assembly. MAIN 28V DC GENERATION SYSTEM The rotor assembly has a rotor winding that connects to the fixed input terminals on the machine housing through a brush/commutator assembly. The machine housing has 4 poles with a four brush block assembly to switch the input or output current to the correct rotor winding. The rotor is held at each end by ball bearings that are mounted in the housing. The ball bearings are pre lubricated with grease when installed and service is not necessary until overhaul. DETAILED DESCRIPTION DC STARTER/GENERATOR The DC starter/generator attaches to the accessory gearbox with a Quick-Attach/ Detach (QAD) adapter that, once installed, stays attached to the gearbox when DC starter/generator is removed. The DC starter/generator connects to the QAD with a V band clamp to secure the assembly. The QAD has an opening that connects to an airframe duct to exhaust cooling air outside of the engine nacelle. The torque force is transmitted to the DC starter/generator through a splined shaft that connects to the engine accessory gearbox. The DC starter/generator drive shaft has a shear section that breaks to protect the accessory gear box drive train from damage when too much torque is supplied. The DC starter/generator is an electromagnetic machine. When it rotates, it will change engine input mechanical torque to output DC electrical power. In the starter mode, it changes input electrical DC electrical power into a mechanical output torque. The DC starter/generator operation is controlled and monitored by the DC Generator Control Unit (GCU). The DC starter/generator is a four-pole, shunt connected, fully compensated DC generator with interpole windings, brush commutation, and an internal cooling fan. It is attached to the aircraft accessory gearbox. The DC starter/generator has a permanent magnet so that it can make output voltage without an external excitation source. The output from the DC starter/generator is sent to the DC GCU. The DC GCU supplies the DC starter/generator with its output voltage until the DC GCU starts regulation. When regulating, the DC GCU supplies a modulated current to the DC starter/generator to maintain a 28.5V DC output. The DC starter/generator has stator and rotor assemblies contained in a cylindrical shaped housing. The housing is made of a high iron content material. It is part of the TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY The DC starter/generator has a fan to supply a forced air flow axially through it to cool the rotor and starter windings, the commutator assembly, and the bearings. Air is drawn from outside the nacelle through NACA vents to keep the operating temperatures satisfactory. The brushes that are used in the DC starter/generator have optimum life when blast cooling is supplied by propeller thrust to lower their temperature. The DC starter/generator electrical power circuit has a 4 pole shunt that operates at 12,000 rpm. The electrical circuit of the DC starter/generator has interpole windings to help the flux path between the stator and rotor to increase generator efficiency. The DC GCU supplies a control current to the shunt field winding of the DC starter/ generator to control its output voltage. The shunt field winding current is amplified by the rotational energy of the engine to make the rated output of 400 A at 30V DC. The DC starter/generator terminal voltage is monitored by the EPCU for CBIT functions. Inputs and outputs of the stator windings are given by connections on the body of the DC starter/generator. Low current connections are made with a circular connector and high power output connections are made to studs mounted on a terminal block. A bonding stud on the housing of the DC starter/generator is used to connect it to the airframe ground potential. The DC starter/generator has a temperature switch that closes a set of contacts when the temperature of the DC starter/generator is excessive. It gives continuity through two pins on the DC starter/generator connector to make the DC GEN HOT indication come on in the caution and warning lighting panel. ATA 24 - ELECTRICAL POWER Issue 6 - January 2023 Page 84 of 308 BOMBARDIER DHC 8-400 (PWC PW150) ELECTRICAL POWER - DC STARTER/GENERATOR LOCATOR TO BE USED FOR MAINTENANCE TRAINING PURPOSES ONLY ATA 24 - ELECTRICAL POWER Issue