How to do differential harmonic test of microcomputer relay protection tester?

Test Method. Before the test, the wiring type of the transformer for differential protection can be modified to y(y0) y, and the balance factor of the low (medium) pressure side can be set to 1, which will make the test easier. During the test, whether it is to apply current only to the high-voltage side, or to the high-voltage and low-voltage sides at the same time, the principle is as follows:

The output fundamental component must be greater than the threshold current of the protection setting;

The initial harmonic content of the output must be able to reliably lock the protection, that is, be greater than the harmonic braking coefficient of the protection setting.

If the transformer wiring type of differential protection is y(y0) and the balance coefficient of the high and low voltage side is not, how to test the proportional braking coefficient of the protection without modifying the setting value?

1) When the "high-side harmonic superposition differential current" is output.

Since both the harmonic component and the fundamental component are applied to the high-voltage side, the two waveform components are affected by the balance coefficient of the high voltage and cancel each other out. Therefore, please refer to the test method as described above.

2) When "harmonics on the high voltage side, differential current on the low voltage side" are output.

In this case, the balance coefficient of the high and low pressure side must be considered separately.

For the sake of convenience, it is assumed that the balance coefficients of the high and low sides are kh and kl respectively, the difference threshold value is id0, and the harmonic braking coefficient is kxb.

The fundamental component of the output of a (assuming output by iB) must be greater than: ID0 kL;

The initial harmonic content of the b output (assuming output by ia) must be greater than: ID0 kxb kh.

Start the test and reduce the harmonics to the differential protection action in steps. Assuming that the harmonic and fundamental currents output by the tester are IA1 and IB1 respectively, the formula for calculating the harmonic braking coefficient is:

kxb＝ixb／ijb＝（ia1/ kh）／（ib1＊kl）

Description.

In the differential test, the device outputs two currents from the IA and IB terminals, which is mainly used to test the differential relay.

The IA phase is used as the action current IDZ, which is fixed as a fundamental wave and has a variable amplitude.

The IB phase is used as the braking current IZD, which can be set to DC, fundamental and secondary current, and the amplitude of each time can be set.

When making the ratio braking characteristic of the differential relay, the braking current value is set at the fundamental value of the IZD, the current value is set at the DC value when the DC magnetization characteristics are used, and the current value is set at the secondary current when the second harmonic braking characteristic is made.

When the output of IZD and IDZ is AC, the maximum current is 30A; When the IGD outputs DC, the maximum current is 10A.

Various settings that need to be entered:

IDZ initial value, change step size, phase;

the amplitude and phase of each order of the IZD;

Manual change Automatic change.

The variables that can be varied in the experiment are the amplitude of the IDZ and the phase of the IDZ.

l Input: During the test, the contact of the component under test can be connected to any switching input terminal.

l Output: two output nodes, one to track the process of the test, close when the test presses "start", and disconnect when the test "stops"; The other way tracks changes in the test data, i.e., it closes when the "or" button is pressed for the first time after the test starts, and disconnects when the test "stops".

l Data recording area: In addition to recording the action time and return time, the two lines on the side display the current values of IDZ and IZ when the action and return are displayed in order.

After the data is set, select "Confirm", the screen will display the relay contact status diagram, select "Start" to start the output for testing, the amount of change in the test can be automatically changed or manually changed, the test method is similar to the AC test. When the relay contact is operated and returned, the test recording area on the screen will display the operating time and return time of the relay under test, and the current values of IDZ and IZD.

Huatian Power HT-702 Microcomputer Relay Protection Tester.

You can find it in the online power bookstore, and mine was also bought online, good luck!

Power workers in the work, often need to use harmonic test, but before use, need to set the parameters, if the parameter settings are incorrect, it is difficult to achieve the test accuracy, this article takes the three-phase current protection tester (also called the microcomputer relay protection tester) as an example, to give you a brief introduction to the three-phase current protection tester how to set the harmonic calculation method.

You can choose how harmonics are calculated on the Parameter Settings property page.

Amplitude calculation: The harmonic value of each voltage and current is displayed in units of "volts" or amperes on the interface, and the output value of the tester is the actual value of the voltage and current displayed on the interface.

Fundamental percentage calculation: harmonics for each voltage and interface current"Output amplitude"with"Amplitude step size"equal to the percentage of the phase harmonic value relative to the phase fundamental value; For example, suppose the fundamental current in the current IA channel is 2A and the second harmonic is 20. Amperes have an amplitude of 2 20%=.

The amplitude step of the variable is also expressed as a percentage of the fundamental. Note that the amplitude of the fundamental wave is still the voltage and current output (in volts or amperes).

Set the test operation mode in the Parameter Settings property page. You can choose from three modes: manual control, automatic increment, and automatic reduction.

If you select the latter two operating modes in the test run mode, you can set the operation mode after the operation of the protective device to the test mode, and you can select two modes: "stop after action" and "return after action". When Return After Action, the output changes from the start to the end point. After the program confirms the relay action, it changes direction and returns to the starting point.

When "stop after action", the output is in the process of transitioning from the start point to the end point, and once the program confirms the relay action, the test is completed.

If the latter two modes of operation are selected in the test mode of operation, you can set the "interval time" between changes in the Parameter Settings property page, and in general, the interval should be set longer than the relay's action (or return) time.

The test methods of the three-phase electric protection tester produced by different manufacturers are similar, and power workers need to be proficient.

Respondent: Huatian Power.