JP2538244Y2 - Automatic reset type overload protection relay - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention belongs] The invention detects an overload state of a load such as a motor and shuts off a power supply when the overload state continues for a set operation time. And an automatic reset type overload protection relay which turns on the power supply after a predetermined reset time.

[Conventional technology]

2. Description of the Related Art FIG. 2 shows a conventional automatic reset type overload protection relay. In FIG. 2, the motor 1 is connected to a power source via a current transformer 2 and a cutoff unit 3. The automatic return type overload protection relay includes a signal generation circuit 4, an operation time setting circuit 5, a cutoff circuit 6, a return circuit 7, and the like. The output terminal of the current transformer 2 is connected to the signal generation circuit 4, When the output of 2 indicates an overload characteristic, the signal generation circuit 4 sends out an overload signal with a predetermined anti-time characteristic set by the operation time setting circuit 5. The signal generating circuit 4 has two output terminals, one output terminal of which is connected to a cutoff circuit 6, which receives an overload signal and which has an output storage circuit 6a provided therein.
Is set, and the shut-off unit 3 is shut off. Further, the other output terminal of the signal generation circuit 4 is connected to a cutoff circuit 6 via a return circuit 7, and the return circuit 7 returns the cutoff circuit 6 a predetermined time after receiving the overload signal. When the shutoff circuit 6 returns, the shutoff unit 3 is turned on. In other words, this relay shuts off the power once the load of the motor etc. becomes overloaded and heats up, so during this time the load cools down or the overload is removed and it can be restarted, and the load automatically continues You can drive.

[Problems to be solved by the invention]

This relay is suitable for any load because the time until the reset circuit receives the overload signal, shuts off the interrupting section, and then resets the interrupting circuit and turns on the interrupting section again is fixed. I can't say. That is, when the return time is shorter than the thermal time constant of the load, the load is restarted in a state where the load is not sufficiently cooled from the heating state, and when this is repeated, the load gradually rises in temperature and eventually burns out. There is a problem. Further, if the return time is set longer than the thermal time constant of the load, a long time is required until the load is restarted, which causes a problem that the load operating rate is reduced.
In particular, when one automatic reset type overload protection relay is used for loads having various thermal time constants, the above problem is remarkably exhibited. Further, this relay has a problem that, even if it takes time to investigate the cause of the overload or remove the cause after the overload operation, the relay is automatically reset and restarted after a predetermined recovery time has elapsed. If the return time is set to be sufficiently long in consideration of the above points, there is a problem that the shut-off unit cannot be immediately turned on even when the cause of the overload is investigated and the cause is eliminated.

The purpose of the present invention is to cooperate with the thermal characteristics of various loads,
Another object of the present invention is to provide an automatic reset type overload protection relay which can temporarily suspend the function of a reset circuit if necessary.

[Means for solving the problem]

In order to achieve the above-described object, the present invention provides an interrupting circuit for interrupting an interrupting section by an overload signal sent from a signal generating circuit in response to an overload current, and a predetermined time after the input of the overload signal. An automatic reset type overload protection relay comprising a reset circuit for resetting the shut-off circuit and re-closing the shut-off unit, wherein a reset time setting circuit capable of arbitrarily setting a reset time of the reset circuit; and During operation, it is manually operated to temporarily stop the operation of the return circuit to hold the shut-off portion in the interrupted state, and is manually operated to release the temporary stop of the return circuit and re-enter the interrupt portion. A recovery stop circuit for setting the recovery time according to the thermal characteristics of the load to be protected by the recovery time setting circuit to obtain an optimum recovery time. Circuit by during operation of the return stop circuit holds the output in the reset state of the recovery circuit performs investigate the cause of to overload so that it can not cycle the load,
When the cause removal is completed, the return circuit is restarted and the load is turned on again.

[Embodiments of the invention]

FIG. 1 shows an embodiment of an automatic reset type overload protection relay according to the present invention. Here, the same components as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, a motor 1 includes a current transformer 2,
It is connected to a power supply via a cutoff unit 3. The automatic reset type overload protection relay includes a signal generation circuit 4, an operation time setting circuit 5, a cutoff circuit 6 having an output storage circuit 6a, a return circuit 7, and the like in the same manner as the conventional one. However, this relay is different from the conventional one in that it has a return time setting circuit 8 having a return time setting switch (not shown) and a return stop circuit 9 having a return stop switch (not shown). That is, the return time setting circuit 8 can arbitrarily set the return time of the return circuit 7 by the ON / OFF state of the return time setting switch. Also, the return stop circuit 9 is
The operation of the return stop switch is operated by a manual operation, for example, an ON operation during the operation of, and the operation of the return circuit 7 is temporarily stopped so that the output of the return circuit 7 can be held in a reset state.
In addition, it can be operated by a manual operation of a return stop switch, for example, an OFF operation to release the temporary stop of the return circuit and to turn on the shutoff unit again.

The operation of this relay is the same as the conventional one, and the signal generation circuit 4 detects the overload of the motor 1 and sends out an overload signal, and the cutoff circuit 6 cuts off the cutoff section 3. At this time, the return circuit 7 returns the shutoff circuit 6 at an arbitrary time set by the return time setting switch of the return time setting circuit 8 and turns on the interrupter 3 again. Therefore, if the return time setting circuit 8 is adjusted to the thermal time constant of the load at that time, the shut-off unit 3 can be turned on again in an optimum state. Further, after the relay overload operation, when it takes time to investigate the cause of the overload or to eliminate the cause, the function of the recovery circuit 7 is temporarily stopped by manually operating the recovery stop switch of the recovery stop circuit 9. The output signal is held in the reset state. Then, when the cause of the overload is eliminated, the temporary stop of the return circuit is released by manually operating the return stop switch of the return stop circuit 9, the return circuit 7 is operated, and the shutoff unit 3 is turned on again.

The return time setting circuit 8 may be set together with the operating time setting circuit 5 by one setting device at the same time. In this case, if the operation time is set longer, the recovery time can be longer, and if the operation time is shorter, the recovery time is shorter.

[Effect of the invention]

According to the present invention as described above, according to the present invention, an interruption circuit for interrupting an interruption section by an overload signal sent from a signal generation circuit in response to an overload current, and a predetermined time after the input of the overload signal An automatic reset type overload protection relay comprising a reset circuit for resetting the shut-off circuit and re-closing the shut-off unit, wherein a reset time setting circuit capable of arbitrarily setting a reset time of the reset circuit; and During operation, it is manually operated to temporarily stop the operation of the return circuit to hold the shut-off portion in the interrupted state, and is manually operated to release the temporary stop of the return circuit and re-enter the interrupt portion. With the provision of the return stop circuit, the return time can be set in accordance with the thermal time constant of the load by the return time setting circuit, the re-operation in the heating state of the load can be prevented, and with the shortest return time Can be started, it is possible to proper operation of the load. In addition, since the function of the return circuit can be temporarily stopped by the return stop circuit, the restart can be postponed until the cause of the overload can be eliminated, and the load is immediately re-applied once the cause of the overload is removed And maintenance of the system is facilitated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic recovery type overload protection relay according to the present invention, and FIG. 2 is a block diagram showing an example of a conventional automatic recovery type overload protection relay. 3: Interruption section, 4: Signal generation circuit, 6: Interruption circuit, 7: Return circuit,
8: Return time setting circuit, 9: Return stop circuit.

Continuation of the front page (56) References JP-A-49-19327 (JP, A) JP-A-55-122420 (JP, A) JP-A-52-114944 (JP, A) JP-A-61-231827 (JP) JP-A-58-163223 (JP, A) JP-A-56-44334 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] An interrupting circuit for interrupting an interrupting section by an overload signal sent from a signal generating circuit in response to an overload current, and the interrupting circuit is returned after a predetermined time from the input of the overload signal. In a self-recovery type overload protection relay including a return circuit for re-inputting the cutoff unit, a return time setting circuit capable of arbitrarily setting a return time of the return circuit,
During the operation of the return circuit, it is operated by a manual operation to temporarily stop the operation of the return circuit to hold the interrupting unit in the interrupted state, and is operated by the manual operation to release the temporary stop of the return circuit and shut off. An automatic reset type overload protection relay, characterized by having a reset stop circuit for re-entering the section.