JPS6318412B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a time-limiting relay as a time-limiting element in a protective relay.

In general, many protective relays have a time-limiting element to trip the circuit breaker after a certain time delay from the detection of an accident in the power system or equipment to be protected, either for protection coordination or to prevent unnecessary operations due to noise. For example, in the re-closing method of electric power systems, the circuit breaker is tripped after a certain period of time after fault detection, and if the fault continues when the circuit breaker is re-closed using a re-closing relay, the circuit breaker is delayed for a certain period of time and the circuit is disconnected. Equipped with a timed element for device tripping.

The present invention provides a protective relay system in which the circuit breaker is tripped due to an accident in the power system or equipment to be protected, and then re-energized. Regarding time-limited relays as an element, the time-limited output in response to an accident and the time-limited output in response to a restart are automatically changed to prevent the spread of failure of the equipment to be protected due to a restart, thereby ensuring appropriate time-limited output. The purpose is to provide time-limited relays.

FIG. 1 shows an embodiment of the present invention, in which the present invention is applied to a time-limited relay that obtains a time-limited output for tripping a circuit breaker in a protective relay that employs a re-closing method. In the figure, timer 1 is set to operate for normal times, timer 2 is set to operate for re-closing, and timer 2 is set to a shorter time limit than timer 1. The timer 3 is set for a time slightly longer than the re-closing time limit of a re-closing relay (not shown). The timer 1 is triggered by the output of an AND gate 4 which uses the ON output of the timer 3 during timed operation as a deterrent signal, and the output of the relay that has detected an accident is given as an input IN to the AND gate 4. Timer 2 is triggered by the output of AND gate 5 whose gate is opened by the ON output of timer 3, and the above-mentioned input IN is applied to the input of this AND gate 5. After the timed operation of timers 1 and 2, the ON output of either one is made into the breaker trip signal OUT of the equipment to be protected through OR gate 6, and when both OFF outputs are established, it is made into the trigger signal of timer 3. .

When a time-limited relay configured in this manner is installed in the circuit breaker tripping signal system, the input IN is turned off (low level) during normal times when there is no accident on the equipment to be protected.
The outputs of timers 1, 2, and 3 are off, the output OUT is also off, AND gate 4 is open, and AND gate 5 is closed. In this state, when an accident occurs in the equipment to be protected and the output of the relay that detected it, that is, input IN, turns on (high level), timer 1 is triggered by the on signal passed through AND gate 4, and the timer After the time period 1, the output of the timer 1 turns on, and this on signal is passed through the OR gate 6 to the breaker trip signal OUT.
An attempt is made to remove the accident from the protected equipment. When the fault detection relay output (input signal IN) turns off due to the disconnection tripping, the outputs (OUT) of AND gate 4, timer 1, and OR gate 6
is turned off, and at this time, timer 3 is triggered and becomes an on signal for that time period, closing the gate of AND gate 4 and opening the gate of AND gate 5.

Within the time limit of the timer 3 that maintains this state, the re-closing relay is turned off and the disconnector is turned on again, and the equipment to be protected is energized again. If the fault has not been resolved even with this re-energization, the input signal IN is turned on by detecting the fault again. This ON signal triggers a timer 2 through an AND gate 5, and after the timer 2 has timed out, the ON output is transmitted to an OR gate 5.
It is taken out as the signal OUT for tripping the circuit breaker again, and the equipment to be protected is energized or disconnected. At this time, in the same way as the above operation, the input signal IN turns off when the power is turned on or off, and the output OUT turns off. Timer 3 is retriggered from this turn off, and turns off after that time limit, returning to the normal state. .

As is clear from the above explanation of the operation, timer 1 is used from the first fault detection to disconnection tripping, and timer 2 is used to detect the fault at re-closing. or the disconnector is tripped,
Since the time limit of timer 2 is set to a shorter time than the time limit of timer 1, if the accident continues even during re-closing, a time limit operation is performed in which the shrunken control is promptly performed. Therefore, if the accident has not been removed by reenergizing the equipment to be protected, the power can be turned off or disconnected at an early stage to prevent the accident from spreading, and in the case of an accident involving human life, it is possible to prevent the accident from spreading again. This can prevent serious accidents in closed circuits. In other words, most accidents on power transmission and distribution lines are instantaneous, such as lightning, and the phenomenon of the accident often disappears once the accident occurs, so reclosing protective relays are used to prevent accidents. It is possible to return to normal operating conditions without recurrence. However, there are also permanent fault conditions such as ground faults caused by wind, rain, ice and snow, short circuits between phases, etc. If the fault continues, the fault will be detected again when the circuit is reclosed.
This accident detection can shorten the short-circuit arc time at the accident point by controlling the shrinking within a short time, thereby preventing the accident from escalating to the point of equipment burnout or fire. Furthermore, the incidence of electric shock accidents is reduced by controlling the re-closing circuit within a short period of time in the event of a ground fault accident. It should be noted that even in the reclosing method, there are restrictions on shortening the time from the first occurrence of an accident to the failure due to protection coordination or to prevent unnecessary operations due to noise.

FIGS. 2 and 3 show other embodiments of the present invention, and the differences from FIG.
This is the case when IN is used as a trigger input (Fig. 3).
In either case, the timer 3 returns to the initial state with one timer operation.

In the circuit of Fig. 2 or Fig. 3, the output of timer 1 or input IN is connected to the set input instead of timer 3.
and R-, which is the output of timer 2 as the reset input.
The same effect can be obtained by providing an S flip-flop and using its set output as the gate input of AND gates 4 and 5.

In addition, although the embodiment shows a case where the configuration is made up of a logic circuit and a timer, the present invention is not limited to this, and the present invention is not limited to this. Of course, it can be configured.

As described above, the time limit relay according to the present invention shortens the time limit at the time of re-turning on compared to the time limit at the time of an accident, so it is possible to prevent the expansion of failures of the equipment to be protected, and provides an appropriate time limit output, which provides re-closing method protection. It has excellent effects when used to close relays, trip circuit breakers, or generate alarms.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is a circuit diagram showing an embodiment of the present invention.
3 and 3 are circuit diagrams showing other embodiments of the present invention. 1, 2, 3...timer, 4, 5...and gate, 6...or gate.

Claims (1)

[Claims] 1. In a time-limited relay of a re-closing type protective relay, a first timer 1 obtains the time limit from the time of detection of the occurrence of an accident in the equipment to be protected to the occurrence of a tripping signal of the disconnector; A second timer 2 is provided which obtains a time limit from the point in time when the continuation of the accident is detected by re-closing the shisha breaker to the generation of a signal for tripping the shisha breaker, which is set to a short time period, and the detection signal of the occurrence of the accident is provided. means (3 to 3) for starting the second timer when the first timer is activated or a detection signal due to the restart of the breaker is given;
6) A time-limited relay characterized by comprising: