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Questions and Answers
A complete time-delay is required before another tap change can take place during the ______ operating mode.
A complete time-delay is required before another tap change can take place during the ______ operating mode.
control
The time-delay circuit is activated when the load voltage goes ______ of band.
The time-delay circuit is activated when the load voltage goes ______ of band.
out
The timer is reset when the voltage stays in-band for at least ______ continuous seconds.
The timer is reset when the voltage stays in-band for at least ______ continuous seconds.
10
In the time integrating mode, the timer is decremented at the rate of ______ seconds for every second elapsed.
In the time integrating mode, the timer is decremented at the rate of ______ seconds for every second elapsed.
When power flows in the normal direction, the PT is connected across the ______ side of the AVR.
When power flows in the normal direction, the PT is connected across the ______ side of the AVR.
AVRs will raise the loading capability on the output side but not on the ______ side.
AVRs will raise the loading capability on the output side but not on the ______ side.
The primary side of the power transformer bank is one of the typical AVR ______.
The primary side of the power transformer bank is one of the typical AVR ______.
The step voltage regulator principle includes a basic ______.
The step voltage regulator principle includes a basic ______.
A step-up autotransformer increases voltage while a step-down ______ decreases it.
A step-up autotransformer increases voltage while a step-down ______ decreases it.
In reverse power flow, the relationship between T2 and V2 causes changes in V1 and ______.
In reverse power flow, the relationship between T2 and V2 causes changes in V1 and ______.
Older types of AVR control required an optional Reverse Power Flow ______ kit.
Older types of AVR control required an optional Reverse Power Flow ______ kit.
The sequence of regulator tap-changer operation can have different ______ states.
The sequence of regulator tap-changer operation can have different ______ states.
If V2 is low, the control signals the AVR to raise the voltage by increasing ______.
If V2 is low, the control signals the AVR to raise the voltage by increasing ______.
A step voltage regulator can show its two fingers for ______-changing.
A step voltage regulator can show its two fingers for ______-changing.
The regulator control theory involves a tap-changing ______ for operation.
The regulator control theory involves a tap-changing ______ for operation.
The equation that governs the relationships in power flow is V1 T1 = V2 ______.
The equation that governs the relationships in power flow is V1 T1 = V2 ______.
Newer AVR controls now have reverse sensing modes as a ______ feature.
Newer AVR controls now have reverse sensing modes as a ______ feature.
The line drop compensator is part of the ______ circuit in voltage regulation.
The line drop compensator is part of the ______ circuit in voltage regulation.
The common reverse sensing mode that ensures normal power flow includes Locked Forward and Locked ______.
The common reverse sensing mode that ensures normal power flow includes Locked Forward and Locked ______.
The customer tapping point is one of the key ______ in the voltage regulation process.
The customer tapping point is one of the key ______ in the voltage regulation process.
In the case of reverse power flow, if T1 remains constant, V1 or the new load side ______ must decrease.
In the case of reverse power flow, if T1 remains constant, V1 or the new load side ______ must decrease.
AVRs are crucial for maintaining voltage stability in the ______ network.
AVRs are crucial for maintaining voltage stability in the ______ network.
The turns ratio is an important factor in determining how voltage at Source A and ______ relate to each other.
The turns ratio is an important factor in determining how voltage at Source A and ______ relate to each other.
The ______ supplies a signal to the control proportional to the line voltage.
The ______ supplies a signal to the control proportional to the line voltage.
The signal from the PT is modified by the line-drop ______ settings.
The signal from the PT is modified by the line-drop ______ settings.
The voltage ______ signals when the voltage goes out of a preset band.
The voltage ______ signals when the voltage goes out of a preset band.
After the voltage has been out of the bandwidth for a preset ______, a signal is sent to the tap-changing motor.
After the voltage has been out of the bandwidth for a preset ______, a signal is sent to the tap-changing motor.
The tap-changing motor will continue to change ______, correcting the voltage on the line.
The tap-changing motor will continue to change ______, correcting the voltage on the line.
The sensed voltage must be within the preset ______ for normal operation.
The sensed voltage must be within the preset ______ for normal operation.
The major components of an ______ include the PT, compensator, and tap changer.
The major components of an ______ include the PT, compensator, and tap changer.
The ______ changing motor operates to correct the voltage when it is outside the specified range.
The ______ changing motor operates to correct the voltage when it is outside the specified range.
Voltage Limiting is used to place both a high and low limit on the output ______ of the regulator.
Voltage Limiting is used to place both a high and low limit on the output ______ of the regulator.
Voltage Reduction allows the regulator to reduce voltage during situations where power demands surpass the available ______.
Voltage Reduction allows the regulator to reduce voltage during situations where power demands surpass the available ______.
The Automatic Load Bonus feature limits the range of regulation when a fixed ______ level is reached.
The Automatic Load Bonus feature limits the range of regulation when a fixed ______ level is reached.
Harmonic Measurement can include various orders such as 3, 5, 7, 9, and ______ harmonic for CL-5A.
Harmonic Measurement can include various orders such as 3, 5, 7, 9, and ______ harmonic for CL-5A.
The ADD-AMP feature in Cooper AVRs allows the operation of the AVR at higher than nameplate ______.
The ADD-AMP feature in Cooper AVRs allows the operation of the AVR at higher than nameplate ______.
By-passing a regulator off neutral will ______-circuit the series winding left energized.
By-passing a regulator off neutral will ______-circuit the series winding left energized.
Do not depress the drag hand reset button for more than ______ seconds.
Do not depress the drag hand reset button for more than ______ seconds.
Lightning protection is connected from line to ______.
Lightning protection is connected from line to ______.
The voltage level for both GE's VR-1 and SM-3 models ranges from ______ to 135.
The voltage level for both GE's VR-1 and SM-3 models ranges from ______ to 135.
The time delay for the GE SM-3 model is between 10 and ______ seconds.
The time delay for the GE SM-3 model is between 10 and ______ seconds.
The band-edge indicator in GE's AVR controls is an ______ for the VR-1 model.
The band-edge indicator in GE's AVR controls is an ______ for the VR-1 model.
The Siemens Type JFR step voltage regulator has a power rating of ______ kVA in one of its configurations.
The Siemens Type JFR step voltage regulator has a power rating of ______ kVA in one of its configurations.
For the Siemens MJ-3A control, the voltage bandwidth is ______.
For the Siemens MJ-3A control, the voltage bandwidth is ______.
Both the GE and Siemens AVR controls feature a ______ indicating light.
Both the GE and Siemens AVR controls feature a ______ indicating light.
The operations counter for the Siemens MJ-XL control is ______.
The operations counter for the Siemens MJ-XL control is ______.
In GE's AVR controls, the data port is available for the SM-3 but ______ for the VR-1.
In GE's AVR controls, the data port is available for the SM-3 but ______ for the VR-1.
The manual control switches for the Siemens MJ-XL include ______, OFF, and Auto options.
The manual control switches for the Siemens MJ-XL include ______, OFF, and Auto options.
Both Siemens AVR models have a motor fuse that is ______.
Both Siemens AVR models have a motor fuse that is ______.
Flashcards
Voltage Level
Voltage Level
The voltage that is desired to be maintained in the system, typically between 119V and 121V.
Voltage Regulator
Voltage Regulator
A device used to adjust the voltage in a power system, usually located at a substation.
Voltage Sensor
Voltage Sensor
The part of the regulator that senses the actual voltage on the power line.
Time Delay
Time Delay
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Line Drop Compensation
Line Drop Compensation
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Tap Changer
Tap Changer
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Tap Changing Motor
Tap Changing Motor
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Potential Transformer (PT)
Potential Transformer (PT)
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Time Delay Feature
Time Delay Feature
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Voltage Averaging Mode
Voltage Averaging Mode
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Timer Reset Condition
Timer Reset Condition
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Time Integrating Mode
Time Integrating Mode
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Reverse Power Flow
Reverse Power Flow
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AVR Impact on Voltage
AVR Impact on Voltage
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Typical AVR Locations
Typical AVR Locations
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Pole-mounted AVRs
Pole-mounted AVRs
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Platform-mounted AVRs
Platform-mounted AVRs
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Step-up/Step-down Autotransformer
Step-up/Step-down Autotransformer
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Step Voltage Regulator
Step Voltage Regulator
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Step voltage regulator tap-changing
Step voltage regulator tap-changing
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Reversing Switch in Step Voltage Regulators
Reversing Switch in Step Voltage Regulators
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Step Voltage Regulator Tap Changing Sequence
Step Voltage Regulator Tap Changing Sequence
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Step Voltage Regulator Control Theory
Step Voltage Regulator Control Theory
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Locked Reverse
Locked Reverse
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Locked Forward
Locked Forward
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Reverse Sensing Modes
Reverse Sensing Modes
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Normal Regulation
Normal Regulation
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Turns Ratio
Turns Ratio
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AVR (Automatic Voltage Regulator)
AVR (Automatic Voltage Regulator)
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Transformer
Transformer
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Voltage Bandwidth
Voltage Bandwidth
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LDC Resistance Volts
LDC Resistance Volts
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LDC Reactance Volts
LDC Reactance Volts
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Band-edge Indicator
Band-edge Indicator
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Manual Control Switches
Manual Control Switches
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Switching Modes
Switching Modes
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Data Port
Data Port
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Supervisory ON/OFF Switch
Supervisory ON/OFF Switch
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Voltage Limiting
Voltage Limiting
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Voltage Reduction
Voltage Reduction
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Automatic Load Bonus
Automatic Load Bonus
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Load Bonus Capability
Load Bonus Capability
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Load Current Ratings
Load Current Ratings
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Series Winding Protection
Series Winding Protection
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Lightning Protection
Lightning Protection
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Bypassing a Regulator
Bypassing a Regulator
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Study Notes
EENG 105: Distribution System & Substation Design - Topic 5
- Voltage Regulators: A system designed for automatic constant voltage maintenance. Designs can be simple feed-forward or include negative feedback, using electromechanical or electronic components.
- Automatic Voltage Regulators (AVRs): Tap-changing autotransformers continuously monitor output voltage, adjusting taps for desired voltage. Voltage regulation is typically 10% raise (boost) to 10% lower (buck) in approximately 5/8 steps (32 steps total).
- Reasons for Installing AVRs: Improve system voltage, enhance quality of service, and meet regulatory standards.
- Effects of AVRs on Voltage Problems: Solved problems include undervoltage, overvoltage, and unbalanced voltage. Problems not solved include voltage sags, swells, and fluctuations.
AVR & Capacitor Bank Functions
- AVR Functions:
- Raise/lower voltage
- Voltage adjustment on source side
- Small voltage step control in varying switching operations with no need for frequent inspection.
- Reduced losses throughout the system
- Reduced thermal loading
- Raises system loading capability
- Capacitor Bank Functions (in conjunction with AVRs):
- Raise/lower voltage (effect displayed by being switched on/off)
- Switching can cause capacitor deterioration in large operations per day.
- Reduced losses can be noticed on the output side.
Typical AVR Locations
- Primary side of power transformer bank
- Secondary of power transformer bank
- Main line of feeder
- Middle of feeder
- Customer tapping point
Voltage Regulator Control Theory
- Potential Transformer: Connected across load side, providing proportional voltage for control and the tap changing motor.
- Line Drop Compensator: Reduces voltage swings, increases voltage during full load, and is connected to the potential transformer to the regulator.
- Voltage Sensor: Compares input voltage to preset value, adjusts control to maintain the voltage level within a given tolerance.
- Time Delay: Allows the regulator to ignore brief voltage variations or corrections but corrects for prolonged out-of-band conditions.
Voltage Regulator Operating Sequence
- Potential Transformer (PT): Provides a signal to the control, proportional to line voltage
- Signal Modification: Through line-drop compensator settings
- Voltage Sensor Signal: Indicates when voltage drops out of the preset bandwidth
- Tap-Changing Motor Activation: Initiates tap changes for voltage correction until returned to the given bandwidth
Major Components of an AVR
- S (Source) Bushing
- L (Load) Bushing
- SL (Neutral) Bushing
- Series Arrester
- Position Indicator: Mechanical pointer for tap switch position, indicating raise/lower limits.
- Electronic Control: Controlling component, with specific features depending on the control type.
Siemens, Cooper, & GE AVR Control Types
- Cooper/McGraw Edison VR-32
- Cooper CL-2/CL-2A
- Cooper CL-4C
- Cooper CL-5A
- GE VR-1
- GE SM-3
Typical Features of an Electronic Control
- Voltage Level Selector
- Bandwidth Selector
- Time Delay Selector
- Band-edge Indicator
- Line Drop Compensation
- Neutral Indicating Light
- Draghand Reset/Neutral Light Test Button
- Internal/External Power Switch
- External Power Terminals
- Voltmeter Terminals
- Motor and Panel Fuses
- Operations Counter
- Data Port
- LCD display
- Keypads
Control Operating Modes
- Sequential: One by one tap changes until reaching the target voltage
- Non-sequential: Single tap change, then reset
- Time Integrating: Timer counts down at a rate; once reaching zero, the timer is reset
- Voltage Averaging: Microprocessor monitors and averages load voltage; taps change to correct; timer reset after voltage within band
Reverse Sensing Modes
- Locked Forward: Control remains in forward direction
- Locked Reverse: Control remains in reverse direction
- Bi-directional: Adjusts in forward/reverse directions based on user thresholds
Regulator Connection Diagrams
- One-phase 3-phase, and other circuit regulations
- Different types of AVR (Wye, Delta connected types)
AVRs Used by Meralco
- Manufacturers of AVRs used for power regulation
Voltage Drop Calculation
- Formula for calculating voltage drop in a copper wire utilizing Length, Area, Current, and constant 0.017
- Formula notes for appropriate use with 25°C copper
Important Reminders
- Series winding protection is distinct from lightning protection measures, with separate wire connections.
- Ensure the regulator is in the neutral position before bypassing to avert potential damage from mismatched impedance
- Avoid holding the drag hand reset button for longer than 5 seconds
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