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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.
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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.
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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.
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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 ______.
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The step voltage regulator principle includes a basic ______.
The step voltage regulator principle includes a basic ______.
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A step-up autotransformer increases voltage while a step-down ______ decreases it.
A step-up autotransformer increases voltage while a step-down ______ decreases it.
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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 ______.
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Older types of AVR control required an optional Reverse Power Flow ______ kit.
Older types of AVR control required an optional Reverse Power Flow ______ kit.
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The sequence of regulator tap-changer operation can have different ______ states.
The sequence of regulator tap-changer operation can have different ______ states.
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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 ______.
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A step voltage regulator can show its two fingers for ______-changing.
A step voltage regulator can show its two fingers for ______-changing.
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The regulator control theory involves a tap-changing ______ for operation.
The regulator control theory involves a tap-changing ______ for operation.
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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 ______.
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Newer AVR controls now have reverse sensing modes as a ______ feature.
Newer AVR controls now have reverse sensing modes as a ______ feature.
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The line drop compensator is part of the ______ circuit in voltage regulation.
The line drop compensator is part of the ______ circuit in voltage regulation.
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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 ______.
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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.
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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.
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AVRs are crucial for maintaining voltage stability in the ______ network.
AVRs are crucial for maintaining voltage stability in the ______ network.
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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.
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The ______ supplies a signal to the control proportional to the line voltage.
The ______ supplies a signal to the control proportional to the line voltage.
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The signal from the PT is modified by the line-drop ______ settings.
The signal from the PT is modified by the line-drop ______ settings.
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The voltage ______ signals when the voltage goes out of a preset band.
The voltage ______ signals when the voltage goes out of a preset band.
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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.
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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.
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The sensed voltage must be within the preset ______ for normal operation.
The sensed voltage must be within the preset ______ for normal operation.
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The major components of an ______ include the PT, compensator, and tap changer.
The major components of an ______ include the PT, compensator, and tap changer.
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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.
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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.
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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 ______.
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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.
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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.
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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 ______.
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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.
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Do not depress the drag hand reset button for more than ______ seconds.
Do not depress the drag hand reset button for more than ______ seconds.
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Lightning protection is connected from line to ______.
Lightning protection is connected from line to ______.
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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.
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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.
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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.
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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.
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For the Siemens MJ-3A control, the voltage bandwidth is ______.
For the Siemens MJ-3A control, the voltage bandwidth is ______.
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Both the GE and Siemens AVR controls feature a ______ indicating light.
Both the GE and Siemens AVR controls feature a ______ indicating light.
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The operations counter for the Siemens MJ-XL control is ______.
The operations counter for the Siemens MJ-XL control is ______.
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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.
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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.
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Both Siemens AVR models have a motor fuse that is ______.
Both Siemens AVR models have a motor fuse that is ______.
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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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Description
This quiz covers Topic 5 of EENG 105, focusing on the design and functionality of voltage regulators and automatic voltage regulators (AVRs). Learn about how these systems maintain voltage levels, the reasons for installing AVRs, and their impact on voltage problems. Test your understanding of various voltage regulation techniques and their applications in distribution systems.
