SU819734A2 - Device for relay testing - Google Patents

Description

(54) RELAY TEST DEVICE

one

The invention relates to devices for testing frequency relays used in relay protection and automation of power systems.

A device U is known that is used to test the down-frequency relay. This device contains a low-frequency generator, a generator of high-frequency pulses, a switch of high-frequency pulses, a main and additional pulse counters, a null indicator reset key, a distributor and an indicator.

When the device is operating, both counters in each of the half-cycles of the low-frequency voltage alternately count the high-frequency impulses. It is also taken alternately to take their readings if the total number of pulses has not reached the specified value. Voltage with decreasing frequency, i.e. from half-period to half-period, the number of recorded pulses increases. When this number reaches the set value (begins to correspond to the setpoint, the relay), the reset is prohibited, and the pulse count goes to

the moment of operation of the investigated relay. The total number of pulses recorded by both counters determines the response time of the down-frequency relay under study.

Such a program of operation (response to an increase in the number of pulses) does not allow the main device to be used when measuring the response time of the frequency poiating relay, since during the tests a low frequency voltage with an automatically increasing frequency, i.e. the number of pulses recorded by the counters will decrease from half-period to half-period, and not increase.

The aim of the invention is to expand the functionality of the device, namely the realization of the possibility of using the device as a measure of the response time of the povity frequency relay.

The goal is achieved by the fact that a relay test device containing a high frequency generator, the output of which is connected to the first input of a high frequency switch, the second input of which is connected to the first output of an additional counter, the third input is connected to the output of a reset switch and the first input distributor, the first output of the high-frequency switch is connected to the first input of the additional counter, and the second output is connected to the upstream input of the additional counter and to the first input of the main counter, the second the stroke of which is connected to the output of the test relay and the diode anode, the third input is connected to the output of the differentiating circuit, and the output is connected to the first input of the indicator, the second input of which is connected to the cathode of the diode and the first output of the distributor, the second output of which is connected to the input of the differentiating circuit, and its second input is connected to the second output of the additional counter; the key information input is connected via a null indicator to the output of the low frequency generator and the input of the relay under test, in addition, a logical And element, the first input of which is connected to the output of the null indicator, the second one with an operation mode switch, and the output of the logic element I is connected to the control input of the reset key. FIG. 1 is a block diagram of the device, and FIG. 2 - graphs illustrating his work. The diagram shows the relay 1 under study, a low-frequency generator 2 a generator of 3 high-frequency pulses, a switch 4 of high-frequency pulses, counters 5, b, a distributor 7, a reset key 8, a null indicator 9, a differentiation circuit 10, an indicator 11, a mode switch 12, a diode 13, element AND 14H of FIG. 2 shows: a - voltage at the output of the low-frequency generator 2; b - pulses recorded by the counter 5; in - the impulses registered by the counter b; g - pulses at the output of the counter b; d - on the voltage at the output of the null indicator 9; and e is the voltage at the output of the element 14. In determining the response time of the over frequency relay, the proposed device operates as follows. The relay 1 under study is supplied with a low-frequency generator 2 with a voltage with an automatically increasing frequency (fig.2.8 the instant of passage of this voltage across the zero time t through the zero at the output of the null indicator 9 arises a pulse passing through the closed reset key 8 to one of the inputs control switch high-frequency pulses 4 When this switch 4 is set to the position shown in Fig. 1, and high-frequency pulses T of the generator 3 high-frequency pulses start to flow to the input of counter 5 (Fig. 2, b). In m The time point tg the counter is filled with pulses completely, the main output of this counter appears a pulse acting on the second control input of the high-frequency pulse switch 4. As a result, the switch 4 is set to the position at which the high-frequency pulses start to flow to the counting input of the counter 6 ( Fig. 2, c). At time t, a predetermined number of pulses (corresponding to the setting of the relay 1 under test) accumulates in counter 6 and a pulse appears at the output of counter 6 (FIG. 2d) passing through of mode switch 12 to a first input of AND gate 14. The second input of AND gate 14 receives pulses (FIG. 2, d) from the null indicator 9 during each passage through the zero input voltage of the relay under investigation. If both inputs of the element And 14 pulses arrive at the same time (at times t and t4 in Fig. 2), then at its output a pulse does not occur. Therefore, the reset key 8 does not open, and the output pulse of the null indicator 9 passes through the reset key 8 to the control input of the switch 4 of the high-frequency pulses, returning it to its original position. From this point in time (t), counter 5 starts counting pulses again. Both counters operate in each of the half cycles, if the frequency of the low-frequency generator 2 does not exceed the settings of relay 1. When counters 5 and 6 work alternately (in the first and second half cycles in FIG 2) the reset of the pulses registered by the counter 5 is made by the first pulse passing to the counting input of the counter b. The reset of the counter b is made by the pulse that occurs at the output of the differentiating circuit 10 when switching the distributor 7. The distributor switches from the moment the counter ends working 5. For this, it controls the voltage that occurs at the intermediate output of the counter 5. Several voltages occur at this output earlier (at the time to, see Fig. 2) of the moment when the counter starts working b. It is necessary. so that the result of the counter's operation would not be affected by its own reset time. When the frequency of oscillator 2 rises to the value of the setpoint, after the end of the counting of a given number, the counter impulses b its output

the pulse (at time t) coincides with the output pulse of the null indicator 9. Therefore, a signal appears at the output of the logic element AND 14 (Fig. 2, e) passing to the control input of the reset key 8. Such a signal must pass to the reset key 8 even in those cases when the moment of passage through the zero of the low-frequency voltage does not strictly coincide with one of the counting pulses, but is located between the last counting pulse of one half-period and the first counting pulse of the next half-period. In order to fulfill this condition, the output pulse of the null indicator 9 is extended in time, which dot is consistently executed by performing the null indicator.

Under the influence of a signal on the control input, the reset key 8 is opened. Therefore, at the moment of time tg, the switching signal to the switch 4 is not received, i.e., after the moment of time t, the counter 6 continues its continuous operation. The counting of pulses by the counter 6 goes until the moment when the investigated relay 1 is triggered (time t, in Fig. 2). Simultaneously with the stop of the counter b at the moment of time t, a voltage is applied through the diode 13 to the indicator 11, which switches it on.

The response time of the investigated relay 1 is determined by the formula:

wed

where n is the number of pulses to which counter 5 is set (its capacity);

Hg is the number of pulses recorded by the counter 6 (indicator reading 11); T - the period of high-frequency pulses.

. This device is easy to switch to the mode of measuring the frequency of its own low-frequency generator

0 2, and also on the mode of measuring the response time of the down-frequency relay. However, the functionality of the device is extended.

The use of the device allows one to automate the testing processes of the over frequency relay, speed up these processes and improve the measurement accuracy.

Claims (1)

1. USSR author's certificate 603915, cl. G 01 R 23/00, 1978 5 (prototype). f2o / jv I H-H1: Se 0ue.f ft. g