Introduction to Voltage Regulator Settings

Transcription

1 Introduction to Voltage Regulator Settings S T U D E N T M A N U A L March 29, 2005

2 2 STUDENT TRAINING MANUAL 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

3 INTRODUCTION TO VOLTAGE REGULATOR SETTINGS 3 STUDENT RESOURCES Learning Steps None. 1. 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.

4 4 STUDENT TRAINING MANUAL Lesson 1: Checking the Regulator Settings Learning Objective:Explain the procedure to determine if the voltage regulator settings are correct. Learning Method:Self-learning + On-the-job Evaluation Method:Knowledge test Introduction Once a voltage regulating device has been installed in a power line system, we must make sure the desired results are being achieved. The procedure 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 voltage standards are being met. If the voltage is not within the limits set out by CSA, the regulator must be set to try and accomplish this standard. The following functions are generic to regulating devices. In order to help understand these controls, we will look at both the 4-step auto booster as well as the 32-step regulator controllers.

5 INTRODUCTION TO VOLTAGE REGULATOR SETTINGS 5 Figure 1. 4-step Auto Booster

6 6 STUDENT TRAINING MANUAL Figure step Regulator Controller Panel

7 INTRODUCTION TO VOLTAGE REGULATOR SETTINGS 7 Lesson 2: Base Voltage Learning Objective:Explain the function of the base voltage setting. Learning Method:Self-learning + On-the-job Evaluation 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. The standard base voltage is generally around 122V; however, this may vary depending on the area. Engineering will set the standards as they see fit.

8 8 STUDENT TRAINING MANUAL Lesson 3: Bandwidth Setting Learning Objective:Explain the function of the bandwidth setting. Learning Method:Self-learning + On-the-job Evaluation 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 would be: 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 low voltage is 3V. Three volts is generally the standard for the bandwidth setting.

9 INTRODUCTION TO VOLTAGE REGULATOR SETTINGS 9 Lesson 4: Time Delay Setting Learning Objective:Explain the function of the time delay setting. Learning Method:Self-learning + On-the-job Evaluation 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.

10 10 STUDENT TRAINING MANUAL Lesson 5: Line Drop Compensator (LDC) Learning Objective:Explain the function of the line drop compensator (LDC). Learning Method:Self-learning + On-the-job Evaluation Method:Knowledge test Introduction The relationship between each of the variables and the actual mechanics of 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

11 INTRODUCTION TO VOLTAGE REGULATOR SETTINGS 11 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 for undesirable voltages due to power factor and amperage on the load side conductor of a regulator. The line drop compensator s purpose is to compensate for the line losses or gains on the load side of the regulator. We know that, even if we have acceptable output voltage at the regulator, as the load increases the voltage drop becomes so great that our last customers have low voltage. We would then have a situation where the voltage goes down at the end of the line like this: By using the regulator line drop compensation function, we can lessen the voltage drop at the end of the line. We do this by programming the regulator to increase the voltage output as the load on the line increases. So, we would have a situation that looks like this:

12 12 STUDENT TRAINING MANUAL In this case, all customers receive an acceptable voltage. The LDC compensates for voltage gains or losses by simulating the load side line resistance and reactance. Two dials, resistance and reactance, make up the LDC. Most overhead lines have a lagging power factor characteristic. An increase in the R setting will tend to cause a call for voltage rise. An increase in the X will tend to cause a call for a voltage rise. With the advent of RUD, leading power factors are becoming more common. An increase in the R setting will tend to cause the call for a voltage rise. An increase in X will tend to cause the call for a lowering of voltage.

13 INTRODUCTION TO VOLTAGE REGULATOR SETTINGS 13 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 to achieve 100%.

14 14 STUDENT TRAINING MANUAL 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.

15 INTRODUCTION TO VOLTAGE REGULATOR SETTINGS 15 Review Question Solutions 1. 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. 2. T 3. T 4. T 5. F 6. T 7. T 8. T