lab1 ece456b

8/13/2019 Lab1 ECE456b

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EC456 – Power System ProtectionLab #1 –Overcurrent Protection Relay

Learning Objectives:

• Understand the building blocks of a numerical protection relay• Understand the HMI of the relay.

• Establish communication between the numerical relay and computero Setting the relayo Monitoring the relay status

• Set the relay parameters for the given system

• Inject balanced rated load to the relay and monitor its measurement online

• Test IDMT characteristics of the relay and plot the theoretical and actual IDMT characteristics

Equipments used

1. SEL351 – Overcurrent relay2. SEL – AMS relay low voltage test kit

Pre-lab assignment

For the section of the power distribution system shown in Figure 1 below, find the current pick-up,time dial for relay Ra. The setting of relay Rb is given below. Use the IEC normal inverse curvegiven by Equation 1.1 for co-ordination.

1

14.0

02.0

−⎟⎟

⎠

⎞

⎜⎜

⎝

⎛ =

p

f

I

I TDt Equation 1.1

Where: M=⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

p

f

I

I – Multiple of pick-up setting

TD– Time dial setting

Setting of relay Rb: Pick up setting = 5A; Time dial = 0.3

Figure 1. Pre-lab assignment.

8/13/2019 Lab1 ECE456b


Procedure

Understanding the relay setting

1. Open “ AcSELerator” software, for communicating with the SEL351 relay (icon on the desktop).2. Open the setting file “Lab #1” (In Settings => Open, select Lab#1)

3. Go through the Group 1\Set 1\ General Settings menu and check the relay general settings:

Figure2. General settings

The relay has been set previously to the following data:

• CTR Phase (I A, IB, IB C ) CT Ratio , CTR:12000

- equivalent to the ratio of (10,000A : 5A)

• PTR Phase (V A, VB, VB C) PT ratio, PRT : 1100.00 (11,000/110)

- equivalent to the ratio of (11,000V : 110V)

Change the phase and neutral CT ratio for the relay Rb defined in the Pre-lab.

4. Go through the Group 1\ Set 1\ Phase Time –Overcurrent and check if Time Delayed PhaseOvercurrent element is enabled (51T). The selection on the top dialog box must be set to “1”

ECE 456b – Lab #1 / 2008 2

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Figure3. Phase Time –Overcurrent settings

• The pick-up setting is set to: 5.00 A

• The IDMT curve is selected as “C1” (IEC normal inverse)

1

14.0

02.0

−⎟⎟ ⎠

⎞⎜⎜⎝

⎛ =

s

f

I

I TDt sec

• The time dial setting is set to 1.0

Change the pick-up setting and time dial setting for the relay Rb defined in the Pre-lab.

5. Check the programming of the output contacts in the Group1\Logic 1\Output Contacts sectionof the setting file. The OUT 101 Outpu t Contact supposed to be set to TRIP.

ECE 456b – Lab #1 / 2008 3

Figure 4. Output contact settings

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6. Save setting file and send it to the relay SEL-351.

First from “File” menu select “Save” and store it in Lab#1_Rb. There are two “File” menus inFigure 4 - choose the one below. Then select “Send” from the same “File” menu and transfersettings file to the device. This procedure takes few minutes.

Injecting a balanced load to the relay

1. We will use SEL-AMS relay low voltage test kit to test the relay2. Start SEL-5401 software (icon on the desktop).3. Open the front panel control interface of SEL-AMS from “Run=>Front Panel Mode”

Figure 5. Front Panel settings

4. On the Front Panel set the three phase current values (IA, IB, IC) to 1.00A and set thephase angles of A, B and C phases to 0, -120 and 120 degrees respectively. Set the threephase voltages VA, VB and VC to 63.5 and phase angles of A, B and C phases to 0, -120 and 120 degrees respectively.

5. Press the start button on the software window.

6. Reset the SEL-351 relay by pressing the TARGET RESET button on the front panel of therelay.

7. On the front panel of the SEL-351 relay press “METER” button and read the data from theLCD display.

8. With the software running, switch to the “ AccSelerator ” window and select “Meter &Control” from HMI menu to monitor the relay status on-line.

ECE 456b – Lab #1 / 2008 4

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Figure 6. Meter and Control window.

9. Read the data from HMI window.

10. Observe the three phase currents and voltages measured by the relay and compare with thevalues injected (Remember that the relay will display the values in primary).

11. Switch to the SEL-5401 software and stop the signal injection from the “Front Panel”module. Close the “ Front Panel” module alone.

Testing the IDMT characteristics

1. You have the loaded IDMT test file, which was created to test the operating time of the relayand plot the IDMT characteristics. Through this test, the relay is being tested for 5 faults.(M=2, 4, 6, 8 and 10)

2. From the SEL5401 software open the pre-created “IDMT” test file (File => Open, selectIDMT.RTA file from the C:\ECE 456\Lab#1 directory).

3. Go through the 12-stage test sequence of the loaded “IDMT” file and understand what isbeing done.

ECE 456b – Lab #1 / 2008 5

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Figure 7. Testing sequence settings

4. Download the test file and run the test by going to “ Run \ Download Test and Run it “ onthe top menu bar.

5. Observe what happens. Wait for the testing to complete.

6. Note down the operating time of the relay from the result displayed after the test iscompleted. The measurements for each of the test stages are displayed on a Result window (Figure 8).

ECE 456b – Lab #1 / 2008 6

Figure 8. Test results

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ECE 456b – Lab #1 / 2008 7

7. Verify the obtained result with the expected theoretical value.

8. Plot the expected and obtained curves on the graph sheet.

9. Repeat the entire experiment for the relay Ra defined in the Pre-lab.

lab1 ece456b

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