JP3267381B2 - Load control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control device for controlling the opening and closing of a load and protecting the load. The present invention relates to a load control device that can perform the load control.

[0002]

2. Description of the Related Art A control center is an example of a load control device having an opening / closing and protection function for an electric motor, a resistance load, and the like. That is, in the control center,
Main units such as electromagnetic contactors, circuit breakers, current converters, and auxiliary relays for control are housed in multiple stages with multiple units assembled for each unit circuit. Each unit has a start switch, stop switch, etc. It is configured by providing an operating device including:

Further, in order to easily cope with the change of the unit, a logic operation circuit comprising a microcomputer is provided in the control circuit, and the logic operation circuit allows the input signal from the operating device and the magnitude of the main circuit current detected by the current converter to be large or small. The main circuit device is controlled according to

[0004]

By the way, in this type of load control device, when a power failure occurs in the control circuit,
Since the state before the power failure, for example, if the motor was running, it is necessary to restart the motor upon power recovery,
Even during a power failure, back up the control circuit power supply,
It is necessary to supply power required for each circuit of the control circuit to operate.

In consideration of the above points, the present invention eliminates the need to provide a backup power supply in order to return to the state before the power failure when power is restored in the power supply of the control circuit. An object of the present invention is to provide a load control device that is excellent in economy and maintainability.

[0006]

According to the present invention, in order to achieve the above object, a control circuit includes a power supply monitoring circuit for detecting a power failure and a power recovery of a power supply of a control circuit, and a time period from a power failure to a power recovery. A timer circuit for measurement and a nonvolatile memory for holding a preset restart guarantee time and an operation state before the power failure during the power failure are provided, and the logic operation circuit detects the power recovery by the power supply monitoring circuit and detects the power recovery by the timer circuit. The measured power outage time is compared with the set value of the restart guarantee time stored in the non-volatile memory, and when it is determined that the power outage time is shorter than the set value, the operation state stored in the non-volatile memory is read and the power outage is performed. It is characterized by being brought to the previous state.

[0007]

According to the present invention, the logical operation circuit determines the operation state of the load before the power failure stored in the non-volatile memory, the preset restart guarantee time, and the power failure time of the power supply obtained by the timer circuit. Thus, it is possible to determine the restart of the load, and it is not necessary to back up the power supply of the control circuit during a power failure.

[0008]

An embodiment in which the present invention is applied to a control center will be described below with reference to the drawings. That is, FIG. 1 shows a circuit configuration of one unit of the control center. In FIG. 1, a main circuit 3 between a three-phase power supply bus 1 and an induction motor 2 as a load includes a circuit breaker 4, an electromagnetic contactor 5, and a current converter for detecting a main circuit current. That is, the current transformer 6 and the zero-phase current transformer 7 for detecting the zero-phase current of the main circuit are interposed as main circuit devices. The primary winding of the operating transformer 8 is connected between two phases of the main circuit 3 between the load side of the circuit breaker 4 and the power supply side of the electromagnetic contactor 5. Control buses 9 and 10 are connected to the secondary winding of the operation transformer 8, and a power supply circuit 12 that supplies a constant DC voltage to a control circuit 11 is connected to the secondary winding.

The control circuit 11 mainly includes a logical operation circuit 13 composed of a microcomputer. The logical operation circuit 13 is composed of a control program stored in a storage circuit 14 composed of a ROM, the current transformer 5 and A current detection circuit 15 for inputting a detection current corresponding to the magnitude of the main circuit current output from the zero-phase current transformer 6 and a protection operation and a control operation based on each signal provided from the input circuit 16 are executed. Has become. The control program stored in the storage circuit 14 includes a well-known program for executing a protection operation such as an overcurrent, an open phase, an undercurrent, or a ground fault, and a control operation such as an instantaneous power failure restart and a timed restart. Have been. The current detection circuit 15 converts the detection current corresponding to the magnitude of the main circuit current output from the current transformer 5 and the zero-phase current transformer 6 into a digital signal and inputs the converted current to the logical operation circuit 13. The input circuit 16 is connected to the control bus 9 via a normally open contact 5a of the electromagnetic contactor 5 and a start operation switch 17 and a stop operation switch 18, which are operation devices, respectively. It is designed to receive it as an input signal. The exciting coil 5b of the electromagnetic contactor 5 has a control bus 9
And the output circuit 19, and the power cutoff is controlled by the logical operation circuit 13 through the output circuit 19. The control circuit 11 is provided with a display device 20 for displaying the state of the motor 2 and the cause of the abnormality.

Here, the control circuit 11 is further provided with a power supply monitoring circuit 21 for detecting a power failure and restoration of the power supply circuit 12, and a signal thereof is inputted to the logical operation circuit 13. The logic operation circuit 13 includes a timer circuit (RTC circuit) 22 for measuring a power failure time until the power failure of the power supply circuit 12 and restoration of power, and a non-volatile memory for storing the state and set values of the electric motor 2 before the power failure of the power supply circuit 12. A non-volatile memory (NOVRAM) 23 is connected, and the timer circuit 22 is provided with a backup battery 24.

In the above configuration, when the power supply circuit 12 has lost its function, the power supply monitoring circuit 21 detects a power failure and sends a power failure signal to the logical operation circuit 13. The logical operation circuit 13 includes a state of the electric motor 2 and a timer circuit 22.
Is stored in the non-volatile memory 23, and a store signal is sent to the non-volatile memory 23 to hold the data. Upon receiving the store signal, the non-volatile memory 23 saves the data to the non-volatile memory cells, and thereafter retains the contents even if power is not supplied from the power supply circuit 12. In addition, the main circuits stop operating due to a power failure of the power supply circuit 12, but only the timer circuit 22
The time keeping operation is continued by the dedicated battery 24.

Next, when the power supply circuit 12 recovers power, each circuit starts operating. First, the logic operation circuit 13 performs necessary initialization processing, and then reads the time T1 from the timer circuit 22. Subsequently, the operation state and the time T0 of the electric motor 2 at the time of the power loss saved in the non-volatile memory 23 are read, and the power outage time t = T1−T0 is calculated from this. This value is compared with a preset restart guarantee time T at the time of a power failure, and T> t
When the state of the electric motor 2 is in operation before the power failure, the logical operation circuit 13 determines this and outputs a restart command of the electric motor 2 to the output circuit 19 to return to the state before the power failure. it can.

As described above, according to the present embodiment, even if the function of the power supply circuit 12 is lost and a power failure occurs, the timer circuit 2
If only 2 is backed up, it is possible to return to the state before the power failure when power is restored. In this case, there is no need to provide a separate power supply and continue to supply power required to operate each circuit of the control circuit 11, so that a load control device excellent in space saving, economy, and maintainability can be provided.

[0014]

As described above, according to the present invention, even when the power supply of the control circuit is interrupted, it is possible to return to the state before the power interruption when the power is restored, and to operate each circuit of the control circuit at the time of the power interruption. Therefore, it is not necessary to continuously supply necessary power, so that a load control device excellent in space saving, economy, and maintainability can be provided.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a load control device according to the present invention.

[Explanation of symbols]

1 is a power bus, 2 is a motor, 3 is a main circuit, 4 is a circuit breaker, 5 is an electromagnetic contactor, 8 is an operation transformer, 9 and 10 are control buses, 11 is a control circuit, and 12 is a power circuit. , 13 is a logic operation circuit, 14 is a storage circuit, 15 is a current conversion circuit, 1
6 is an input circuit, 19 is an output circuit, 20 is a display circuit, 21
Denotes a power supply monitoring circuit, 22 denotes a timer circuit, and 23 denotes a nonvolatile memory.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02H 3/06 H02P 7/36

Claims (1)

(57) [Claims] 1. A main circuit device for opening / closing and protecting a load, and an operation device for operating the load, and the main circuit device is operated in accordance with an input signal and a main circuit current by the operation device. In a load control device having a control circuit having a logical operation circuit for performing control based on a control program stored in advance, a power supply monitoring circuit for detecting power failure and restoration of a power supply of the control circuit, A timer circuit for measuring the time from power failure to power recovery of the power supply, and a nonvolatile memory for holding a preset restart guarantee time and an operation state before the power failure during the power failure of the power supply. The power failure time is detected by the monitoring circuit, and the power failure time measured by the timer circuit is compared with the measured value of the restart guarantee time stored in the nonvolatile memory. When it is determined that the load is short, the operation state stored in the non-volatile memory is read and the state before the power failure is restored.