Introduction to Voltage Regulator Settings 4 Book 1/18. INTRODUCTION T… · is known as compensator voltage. The compensator voltage is then sent to the voltage sensor. 5. The voltage

March 29, 2005

S T U D E N T M A N U A L

Introduction to Voltage Regulator

Settings

Copyright 2004 by the Training and Development Centre, SaskPower. All Rights Reserved

2 S T U D E N T T R A I N I N G M A N U A L

Prerequisites: • Introduction to Voltage Regulation module.

Objectives: Given a regulating device and the appropriate controller, you will be able to describe and/or set the base voltage, band width, time delay and the line drop compensator.

Rationale: As a powerline technician, you will be required to maintain a standard of voltage quality, and regulation is a large part of this.

Learning Objectives• Explain the procedure to determine if the voltage regulator settings

are correct.• Explain the function of the base voltage setting.• Explain the function of the bandwidth setting.• Explain the function of the time delay setting.• Explain the function of the line drop compensator (LDC).

Learning Methods• Self-learning + On-the-job• Self-learning + On-the-job• Self-learning + On-the-job• Self-learning + On-the-job• Self-learning + On-the-job

EVALUATION METHODS

• Knowledge test• Knowledge Test• Knowledge test• Knowledge test• Knowledge test

I N T R O D U C T I O N T O V O L T A G E R E G U L A T O R S E T T I N G S 3


STUDENT RESOURCES

• None.

Learning Steps1. Read the Learning Guide.2. Follow the steps outlined in the Learning Guide.3. Clarify any questions or concerns you may have.4. Complete the Practice and Feedback.5. Complete the Evaluation.



Lesson 1: Checking the Regulator SettingsLearning Objective:Explain the procedure to determine if the voltage regulator

settings are correct.Learning Method:Self-learning + On-the-jobEvaluation Method:Knowledge test

Introduction

Once a voltage regulating device has been installed in a power linesystem, we must make sure the desired results are being achieved. Theprocedure to ensure we are achieving adequate regulation is as follows:

• Test the accuracy of a volt meter• Check the voltage at the first and last customer on the load side of

the regulation device(s).• Services with no load are preferred. This is to avoid dealing with a

line loss factor from secondary wire.• Digital recording voltmeters (DRV) may be beneficial as the history

can be taken into consideration.• The voltage checks are to be within the limits of the extreme

operating range (106/212V to 127/254V for a 120/240V service).

Voltage Regulator Settings

Once a voltage check is completed, we can determine if the CSA voltagestandards are being met. If the voltage is not within the limits set out byCSA, the regulator must be set to try and accomplish this standard.

The following functions are generic to regulating devices. In order tohelp understand these controls, we will look at both the 4-step autobooster as well as the 32-step regulator controllers.



Figure 1. 4-step Auto Booster



Figure 2. 32-step Regulator Controller Panel



Lesson 2: Base VoltageLearning Objective:Explain the function of the base voltage setting.Learning Method:Self-learning + On-the-jobEvaluation Method:Knowledge Test

Base Voltage• Best defined as the desired voltage to be maintained with no load on

the line. This desired level is set using the voltage level setting. Thestandard base voltage is generally around 122V; however, this mayvary depending on the area. Engineering will set the standards asthey see fit.



Lesson 3: Bandwidth SettingLearning Objective:Explain the function of the bandwidth setting.Learning Method:Self-learning + On-the-jobEvaluation Method:Knowledge test

Introduction• Can be explained as the voltage band which the regulating device is

going to operate within. The bandwidth is set using the bandwidth control knob. An example of the bandwidth is as follows:

Base voltage = 122V

Bandwidth = 3V

The highest the voltage could rise to without any taps occurring wouldbe:

122V + 1.5V = 123.5V

The lowest the voltage could dip without any taps occurring would be:

122V - 1.5V = 120.5V

As you can easily see, the difference between the high and the lowvoltage is 3V. Three volts is generally the standard for the bandwidthsetting.



Lesson 4: Time Delay SettingLearning Objective:Explain the function of the time delay setting.Learning Method:Self-learning + On-the-jobEvaluation Method:Knowledge test

Introduction• Can best be described as a timing delay in the tap changer operation.

This delay is required in order to avoid unnecessary tapping due to fluctuating voltage. This setting is controlled by the time delay control knob.

• A time delay is set at all regulating devices with a time delay option. The time delay at a substation will be set at approximately 45 seconds. The first regulating device, usually a 32-step three-phase regulator site, will have a 60 second delay. The next regulating device will be set at 75 seconds of delay before tapping. This timing carries on until the last device. Auto boosters are generally set for a 2 min. delay, if not more.



Lesson 5: Line Drop Compensator (LDC)Learning Objective:Explain the function of the line drop compensator (LDC).Learning Method:Self-learning + On-the-jobEvaluation Method:Knowledge test

Introduction

The relationship between each of the variables and the actual mechanicsof the tap changer are best illustrated by this seven step line diagram.

1. The variables that are of concern on a line are: current, resistance and reactance. These combine for either a voltage loss or a voltage gain.

2. The LDC has a resistance dial and a reactance dial (R and X). The actual devices they represent are in series with the



secondary side of a CT. The CT measures actual line amps at the regulator.

3. The CT’s secondary current, flowing through the R + X (impedance) of the LDC creates a voltage drop.

4. This voltage drop in the LDC is subtracted from the PT and is known as compensator voltage. The compensator voltage is then sent to the voltage sensor.

5. The voltage sensor will then cause the tap changer to satisfy the sensor’s own parameters.

6. The call for a raise is recognized by the time delay, but the signal to the tap changer is delayed according to the time setting.

7. The tap changer operates until the raise in line voltage increases PT voltage to a level necessary.

So far, we have not incorporated the ability to compensate forundesirable voltages due to power factor and amperage on the load sideconductor of a regulator. The line drop compensator’s purpose is tocompensate for the line losses or gains on the load side of the regulator.

We know that, even if we have acceptable output voltage at theregulator, as the load increases the voltage drop becomes so great thatour last customers have low voltage. We would then have a situationwhere the voltage goes down at the end of the line like this:

By using the regulator line drop compensation function, we can lessenthe voltage drop at the end of the line. We do this by programming theregulator to increase the voltage output as the load on the line increases.So, we would have a situation that looks like this:



In this case, all customers receive an acceptable voltage.

The LDC compensates for voltage gains or losses by simulating the loadside line resistance and reactance. Two dials, resistance and reactance,make up the LDC.

Most overhead lines have a lagging power factor characteristic. Anincrease in the “R” setting will tend to cause a call for voltage rise. Anincrease in the “X” will tend to cause a call for a voltage rise.

With the advent of RUD, leading power factors are becoming morecommon. An increase in the “R” setting will tend to cause the call for avoltage rise. An increase in “X” will tend to cause the call for a loweringof voltage.



Summary

To summarize this module, you have learned:

• How to ensure the regulator settings are correct.• The controls for the various regulator settings.• How to set the various regulator settings.

Practice Feedback

Review the lesson, ask any questions and complete the self test.

Evaluation

When you are ready, complete the final test. You are expected toachieve 100%.



Review Questions

1. Choose the best statement explaining how to tell if a voltage regulator is set correctly.(a) Check voltage at last customer. Voltage should

be 105V/210V minimum.(b) Check voltage at first customer on load side of

regs. Voltage should be 128V/256V maximum.(c) Use DRV’s to avoid a bunch of driving around.(d) Test accuracy of volt meter. Check voltage at first

and last customer on load side of regs. Voltage is to be 110V/220V to 125V/250V preferably.

T / F 2. Extreme voltage range for a 120V service is a low of 106V and a high of 127V.

T / F 3. Base voltage is best defined as the voltage to be maintained with no load on the line.

T / F 4. The bandwidth setting is explained as the voltage band which the regulating device is going to operating within.

T / F 5. The bandwidth setting sets the voltage to the extreme low voltage rating.

T / F 6. The time delay setting delays the top changer from operating on sudden voltage regulation.

T / F 7. The line drop compensator’s purpose is to compensate for the line losses or gains on the load side of the regulator.

T / F 8. The line drop compensator lies to the controller so it sees a voltage drop on the end of the line.



Review Question Solutions

1. Test accuracy of volt meter. Check voltage at first and lastcustomer on load side of regs. Voltage is to be 110V/220Vto 125V/250V preferably.

2. T

3. T

4. T

5. F

6. T

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Documents

Introduction to Voltage Regulator Settings 4 Book 1/18. INTRODUCTION T… · is known as compensator voltage. The compensator voltage is then sent to the voltage sensor. 5. The voltage