Secondary Current Injection Test Set

Secondary current injection test set not only used for test all traditional relays and protection devices, but can also carry on all kinds for modern various microcomputer protection, especially for transformer differential protection and automatic transfer switch equipment.

1. Secondary Current Injection Test Set has Six phase voltage and six phase current can be output, which has made it is possible to be any combination.

2. Available to connect with a computer or a desktop compute directly .

3. Output port with high fidelity and high reliability function and excellent performance.

4. The output part adopts DSP control, which has fast operation, real-time digital signal processing capability, wide bandwidth and high resolution D/A conversion control.

5. It can complete all kinds of high automatic validation work which is large and complex.

6. 110V and 220V adjustable DC power is designed to supply output.

7. With USB communication port，Secondary Current Injection Test Set can communicate with the computer and other external devices.

8. With power soft start function and the software of the fault self-diagnosis and the output latch function.

AC current output

Output current per phase under 6-phase output: 0～30A output precision 0.1 grade

Output current per phase under 3-phase output: 0～60A

Output current when 6-phase in parallel : 0～180A

Allowed phase current for long time working: 10A

The maximum output power of phase current 450VA

The maximum output power when 6-phase in parallel: 1000VA

The allowed working time when 6-phase in parallel: 10s

Frequency range（fundamental wave）: 0～1000Hz

Harmonic times: 0～20

DC current output

Current output: 0～±10A / phase output precision 0.2 grade

The maximum output load voltage: 20V

AC voltage output

Phase voltage output: 0～120V output precision 0.1 grade

Line voltage output: 0～240V

Output power of phase voltage/ line voltage : 80VA / 100VA

Frequency range（fundamental wave）: 0～1000Hz

Harmonic times: 0～20

DC voltage output

Phase voltage output: 0～±160V output precision 0.2 grade

Line voltage output: 0～±320V

The output power of phase voltage/ line voltage 70VA / 140VA

Input and output

8 channels input

Idle contact : 1～20mA，24V

Electric potential contacts: “0"：0 ～ +6V； “1"：+11 V ～ +250 V

4 pairs switch output: DC：220 V／0.2 A；AC：220 V／0.5 A

Time measurement range

0.1ms ～ 9999s ， measurement accuracy ＜0.1ms

Test System

Factory Release test

The ‘High-Low Frequency Test’ module is mainly used for testing all functions of frequency protection including low frequency load-reduction and high frequency generator_shutting. According to its functions, this module is divided into six test units.

All test items includes almost all frequency and high-low circle protection.

The frequency can slip down to do low- frequency load-reduction test, and can also slip up to do high-frequency test.

Test items of Secondary Current Injection Test Set

There are six test items available, they are ‘Action Frequency’, ‘Action time’, ‘df/dt block’, ‘dv/dt block’, ‘Low Voltage block’ and ‘Low Current block’. According to request, one or more items can be selected. When more than one are selected, corresponding dialog box will be ejected after completing a test item to tell you next test item.

testing objects includes ‘Low Cycle Protection’, ‘Frequency Relay’, ‘Beat Frequency Relay’, ‘Low Frequency Relay’ and ‘High Frequency Relay’ five kinds of relays. The ‘Low Circle Protection’ will be selected under the default situation. Its pulldown menu is as the diagram shows:

Testing Parameters

Time Delay before Variety of Frequency

During each changing process of variable, the device will firstly output the rated power 50Hz, which will be maintained to the end of ‘Time Delay before Variety of Frequency’, then it begins to vary. For testing some protection this is very useful, which can be used for releasing block after the frequency protection is blocked.

Test Interval

After completing one test the device will stop output till the end of ‘Test Interval’, and then it outputs to do next test.

Setting Value

There is inputting box of setting value in every page of test function. Most of these setting values do not work during the test, which only has a function of reference and contrast after the test. You can set the ‘Error Allowance’ if need. After contrasting the ‘Test Value’ got from test with the ‘Setting Value’, a relative error will be obtained for reflecting performance of protection.

Action Frequency

Frequency Test Range

During the test, frequency varys from original value to final value in the test range, the original and final value should be set so that the action frequency is placed between them, When Varying from original value to final value frequency should stride over the setting action value so that the protection can act.

Test mode of action frequency: Frequency will vary in two stages during the test: At the beginning, it output the origin frequency. After delaying the time before the variety, it will firstly slip down (or up) evenly according to df/dt to the frequency 0.2Hz higher (or lower) than setting action value. Then, it will descend (or rise) the frequency step by step in certain time interval according to setting step size. If the protection acts during this process, the action value will be obtained. Otherwise, it will consider that the protection won’t act and end this test item when frequency varys to the final value.

The time interval of step-by-step frequency varying is confirmed automatically according to setting action time, and this time interval is 0.2s longer than setting action time. So the setting action time must be set correctly in order to ensure that the protection has enough time to act in the time interval of variety. Similarly, the setting action frequency also must set correctly in order that the protection can act in the stage frequency varying step-by-step.

For example: known low frequency action value is 48.5 Hz, the test range should be set 50 — 48Hz, and the step size is 0.05Hz, the testing final value should not be set too lower (normally higher than 45Hz), otherwise, the protection maybe will block.

Action time

Test mode of action time: frequency slips down (or up) from original value (normally 50Hz) to final value and waiting for action. This final value should be lower than frequency action value for ensuring action of protection. But the timer for testing action time begins to time it from ‘Setting Action Frequency’. So if the setting value has deviation, it will influence the time measuring precision. For process of test, please see the right diagram.

df/dt Block

df/dt Test Range

When testing the ‘df/dt block value’, it will do tentative test point by point in the test range. The frequency will slip down (or up) from original value to final value every time. The df/dt value slipping down (or up) will vary point by point in this range. When the protection acts in certain time test, the boundary value of df/dt block at that time will be tested out.

Since the protection is blocked when the df/dt value is larger than setting value, the original value of df/d should be higher and the final value should be lower than the setting block value of protection, which means during the test from protection no action to action, the dv/dt block value will be tested out.

Range of Frequency Variety

In each period, testing frequency slips down (or up) from original value to final value. The original value is normally 50 Hz, and the final value is lower (or higher) than setting action frequency.

Attention：

Time delay before frequency variety when doing this test could not be too shorter in order that there are enough times for protection to release block.

dv/dt Block

This testing item is very similar to ‘df/dt block’ mentioned in the above paragraph. Their difference is that the variable in each test period is dv/dt value. We only introduce their differences in the following paragraph.

dv/dt Test Range

It will do tentative test point by point in this range when testing ‘dv/dt block value’. Voltage will slip down from original value to final value when doing the test every time. The dv/dt value slipping down will be varied point by point in test range. When the protection acts in certain period of tentative test, the boundary value of dv/dt block will be tested out.

Since the device is in the block state when the dv/dt is higher than the setting block value, normally the original value should be set higher than the setting block value, and the final value should be set lower than the block value. Which means during the test from protection no action to action, the dv/dt block value will be tested out.

Varying Range of Voltage

For simulating the process of voltage’s descension, normally the ‘Original Value of Variety’ of voltage should be set higher than the ‘Final Value of Variety’. Meanwhile, for avoiding the low frequency protection from being blocked due to low voltage, the ‘Final Value of Variety’ of voltage set should be higher than the setting low-voltage block value of the protection.

df/dt value in testing

Frequency in this testing item always varies along according to gived df/dt, so df/dt should be set lower than the setting df/dt block value of the protection.

Low Voltage Block

This item is similar to ‘df/dt block’ and ‘dv/dt block’ in above paragraph. We introduce their difference as follows:

Test Range of Voltage

Voltage will do tentative testing point by point in test range. In every period of test frequency will vary but voltage will be fixed to certain value. Voltage increases from the original value to final value step-by-step. When it is increased to certain value, the device release block to act, so this value is the boundary value of low voltage block.

Since the protection is blocked when voltage is lower than the block value, normally the original value of voltage should be lower and the final value be higher than the block value. Which means during the test from protection no action to action the dv/dt block value will be tested out.

Low Current Locking

This testing page is very similar to ‘Low Voltage Block’. Please refer to the instruction for ‘df/dt block’, ‘dv/dt block’ and ‘low voltage block’.

We only take the ‘Test of Low Frequency Action Value’ as example, to explain the test method in details.

Connecting Mode

Connecting three phase voltage UA, UB and UC of tester with three phase voltage of relay; connecting UN of tester with UN of relay; connecting digital input A and B of tester respectively with the trip terminal of primary and secondary stage load-reduction of relay, and connecting common end of digital input of tester with the trip common terminal of relay, then turn on the power supply of relay. (If the relay needs DC power supply, the power can be lead out from the Aux DC power supply on the rear panel of tester.)

Option

In the “Frequency and High-Low Circle Protection’ testing module, select the ‘Action Frequency’ test item and testing object of ‘Low Circle Protection’;

Set

Switch to ‘Action Frequency’ test interface to set testing data, like the right diagram shows:

Setting Action Frequency

Set this item according to the settings list of relay or actual action valued by protection. This setting item is only for reference during the test and do not influence test result.

Setting Action time

Set this item according to the settings list of relay. The inteval of frequency varying step by step in the second stage is 0.2s longer than this value. If it is too short, the relay may has not enough time to act, so this value should be set correctly.

Test Range of Action Frequency

‘Initial Frequency’ must be higher than the action frequency set by protection, and ‘Final Frequency’ must be lower than it, that means action frequency should be placed between them.

Step Size of Variety of Frequency

‘Variety Step Size’ should be set according to the precision required by the test, normally it can be set in 0.05Hz defaulted.

df/dt Value When doing the Test

It stands for the speed of evenly frequency conversion in the first stage during the process of descending frequency, and df/dt value should be lower than the locking value set by protection.

Button for Starting the Test by Secondary Current Injection Test Set

After confirming all testing parameters are correct, the test can be started. During the test, current real-time frequency output by tester can be observed through the column of ‘Current Frequency Hz’. When the tester does not output voltage, the ‘Abnormity’ lamp on protection will light up. When output frequency of tester is lower than the ‘Start-up Value’, the ‘start-up’ lamp on protection will light up, that is to start up low circle action components.

Process of test is as follows: output 50Hz voltage-current, after delaying time before variety—— frequency slips down evenly in the speed of df/dt to ‘Original Value of Test’ —— press ‘Step Size of Variety’ to reduce frequency in the time interval of ‘Setting action time + 0.2 seconds’ step by step, and also record whether the protection acts.