JPS6288424A - Load opening/closing device - Google Patents

Abstract

PURPOSE:To eliminate the need for the adjustment of relay contact interval by using an ON delay circuit and an OFF delay circuit to apply on/off control of a switching element and a relay coil. CONSTITUTION:When an input signal is fed between input terminals I1, I2, the OFF delay circuit 12 flows a current to a light emitting element T to light the element T. The lighting is received by a photodetector J to trigger a triac Q to be conducted. The ON relay circuit 11 flows a current to a relay coil X for a prescribed time to close a relay contact Xb. When the input signal is interrupted, the ON delay circuit 11 shuts the current to the relay coil X momentarily. Since the OFF delay circuit 12 keeps the current supply to the light emitting element T for a prescribed time, the triac Q keeps the conduction to continue the supply to the load. After a prescribed time, the current to the light emitting element T is shut to make the triac nonconductive at zero crossing thereby interrupting the power application to the load.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention relates to a load switching device that turns on and off power using semiconductor switching elements such as thyristors, triacs, and transistors, and that energizes the load through contacts in a steady state. It is something.

[Prior art and its problems] Conventionally, as a load switching device, one shown in FIG. 4 is known. In the figure, 1 is an input signal circuit, and 2 is a load circuit. The input signal circuit 1 includes a relay coil X connected between a pair of input terminals It and I2.

In the load circuit 2, a semiconductor switching element Q, for example, the first and second electrodes of a triac, and a relay contact xb of the relay coil X are connected in parallel between power terminals PI and P2, and a trigger terminal of the triac Q and a first Another relay contact Xa is connected between the electrodes via a resistor R21.

The relay contact Xa is configured to turn on quickly and turn off slowly, for example by setting the contact interval between the movable contact and the fixed contact smaller than that of the other relay contacts xb. E is an AC power supply, and RL is a load.

In the above configuration, when an input signal is applied between input terminals II and I2, relay coil is triggered, and after a predetermined delay time Tl during which this triac Q is in a steady energized state, another relay contact xb is closed, and the load RL is energized through this relay contact xb.

Next, when the input signal is cut off and the relay coil X is demagnetized, the relay contact Xa opens later than the relay contact Xb, and after a predetermined delay time T2 after the relay contact Since it is open, the load current is cut off by the triac Q. The trigger Q is then extinguished at the zero cross of the power supply voltage, thereby cutting off the current supply to the load RL.

In this way, since the load current is turned on and cut off by the triac Q, no arc is generated at the relay contact xb when the load current is turned on and cut off, and the life of the contact can be extended. Since a large radio wave flows to the load RL through the relay contact xb and no load current flows to the triac Q, burnout due to heat generation of the triac Q can be prevented.

However, the relay contact Xa is different from the other relay contact xb.
It must be configured so that the ON operation is faster and the OFF operation is slower than that of the contact point, and it is extremely difficult to adjust the contact distance between the movable contact and the fixed contact.

In particular, when attempting to simultaneously open and close a plurality of load circuits 2 for one input signal circuit 1, not only does the number of relay contacts Xa and xb incorporated in one relay coil X increase, but also the number of relay contacts Xa and Turn on contact Xa and relay contact xb.

Since it is necessary to provide a time difference in the OFF operation and a difference in current carrying capacity, the structure becomes large and complicated, and it is difficult to provide electrical insulation between the relay coil X and each relay contact Xa and xb. There is a drawback.

In addition, the three load circuits 2 are connected to R, S, and T of the three-phase AC power supply E.
When driving and controlling a load RL consisting of one electric motor, the variation in the ON operation of the triac Q, which is based on the variation in the ON operation between the relay contacts Xa built into each load circuit 2, will directly affect the motor. This has the drawback of leading to vibrations of the load RL.

[Object of the invention] This invention was made in order to eliminate the above-mentioned drawbacks,
Existing contact relays can be used without the need to adjust the contact spacing of the relay contacts, and the ON
, it is an object of the present invention to provide a load switching device that allows easy timing adjustment of OFF operation.

[Configuration and Effects of the Invention] The load switching device according to the present invention includes an ONN circuit in the input signal circuit that excites the relay coil after a predetermined delay time from the application of the input signal and demagnetizes the relay coil when the input signal is cut off. 9 circuit and an OFF delay circuit that energizes the trigger element of the semiconductor switching element when the input signal is cut off and cuts off the energization to the trigger element after a predetermined delay time from the time the input signal is cut off. has.

With the above configuration, ON/OFF control of the switching element and relay coil is achieved by the No delay circuit and OFF delay circuit, and there is no need to adjust the contact spacing of the relay contacts, so existing contact relays can be used. Moreover, the O of the above switching element and relay coil can be
The timing adjustment of N and OFF can be easily achieved using an electronic NO delay circuit and an OFF delay circuit.

[Explanation of Examples] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing an example of a load switching device according to the present invention, in which the same parts as in FIG. 4 are given the same numbers.

In the figure, an ON delay circuit 11 and an OFF delay circuit 12 are connected in parallel between a pair of input terminals It and I2, and the ON delay circuit 11 is an electronic circuit that delays only the ON operation of the relay coil X for a predetermined period of time. be. T is OF
A light emitting element driven by the F delay circuit 12,
- The OFF delay circuit 12 is an electronic circuit that delays only the ON operation of the light emitting element T for a predetermined period of time. Further, in the trigger circuit of the triac Q in the load circuit 2, a light receiving element J, such as a photodetector, which receives light from the light emitting element T, is inserted.

FIG. 2 is a circuit diagram showing a specific example of the input signal circuit 1, in which reference numeral 11 indicates 49 ON/OFF circuits, 12 indicates 1 OFF/OFF circuit, or a relay coil, and T indicates a light emitting element.

A series circuit of resistor R1 and capacitor CI is connected between positive and negative signal lines LL and L2 to constitute a time constant circuit, and a voltage dividing point a1 of this time constant circuit is connected via resistor R2. While the base of the transistor TRI is connected,
The collector of the above transistor TRI has a relay coil X.
is connected to the emitter of the transistor TRI, and furthermore, a constant voltage element S consisting of a varistor and a capacitor C2 are connected to the emitter of the transistor TRI.
are connected in parallel. A series circuit of a diode DI and a Zener diode ZD1 is connected in parallel to the relay coil
This is to prevent it from burning out.

A series circuit of resistors R3 and R4 is connected to the time constant circuit consisting of the resistor R1 and capacitor C1, and the base of a transistor TR3 is connected to the voltage dividing point a2 via a diode D2 in the opposite direction. In addition, the emitter of the transistor TR3 is connected to the base of the transistor TRI, and the collector of the transistor TR3 is connected to the negative signal line L2.

The ON delay circuit 11 for the relay coil X is configured with the above configuration.

After this ON delay circuit 11, a series circuit of a resistor R5 and a capacitor C3 is connected to positive and negative signal lines LL,
A Zener diode ZD2 is connected in parallel to this series circuit to maintain a constant voltage between the positive and negative signal lines L1 and L2.

The Zener diode ZD2 includes a time constant circuit consisting of a series circuit of a resistor R6 and a capacitor C4, and a resistor R8.
and R9 are connected in parallel, and a Zener diode ZD3 for maintaining the voltage across the capacitor C4 at a constant voltage and a discharge resistor R7 are connected in parallel to the capacitor C4.

The voltage dividing point a3 between the resistor R6 and the capacitor C4 is connected to the positive terminal of the differential amplifier OF, and the voltage dividing point a4 between the resistors R8 and R9 is connected to the positive terminal of the differential amplifier OF.
are respectively connected to the negative terminal of the differential amplifier OF. A capacitor C is connected between the positive and negative terminals of the differential amplifier OF above.
5 also has resistors RIO and R between the negative terminal and the output terminal.
11 are connected to each other to form an integral differential amplifier. The base of a transistor TR2 is connected to the output terminal of this differential amplifier OP, the light emitting element T is connected to the collector of this transistor TR2, and the emitter of the transistor TR2 is connected to a negative signal line L2. In addition, D3. D4 and D5 are diodes for preventing backflow.

In the above configuration, now the input terminal It in FIG.
, I2, the potential at the voltage dividing point a3 between the resistors R6 and R7 in the OFF delay circuit 12 is set to be higher than the potential at the voltage dividing point a4 between the resistors R8 and R9. Therefore, the output of the differential amplifier OF is H.
level, and the transistor TR2 instantly becomes conductive, causing the light emitting element T to emit light. The light from the light emitting element T is received by the light receiving element J shown in FIG. 1, which triggers the torch Q to conduct.

On the other hand, when the input signal is applied, the ON delay circuit t
The potential at the voltage dividing point a2 between the resistors R3 and R4 in i rises faster than the potential at the voltage dividing point a1 between the resistor R1 and the capacitor C1 forming the time constant circuit, and the transistor TR
3 becomes conductive before transistor TR1. This l・
Due to the conduction of the transistor TR3, the base (2) does not flow through the transistor TR1, so that it is maintained in a non-conductive state, and the relay coil X is not energized.

As a result, when an input signal is applied, the load RL is first energized through the triac Q.

When the capacitor CI reaches a predetermined potential of -1-+A after a predetermined time from the application of the input signal, the constant voltage element S in the ON delay circuit 11 becomes conductive, the transistor TRI becomes conductive, and the relay coil X is driven. , closes relay contact xb shown in FIG. As a result, the load R
Electricity is supplied to L via this relay contact xb.

Next, when the input signal is cut off, the charge of the capacitor CI in the ON delay circuit 11 is transferred from the resistor R2 to the emitter of the transistor TR3 to the base to the diode D2.
→ The wave passes through the resistor R4 and makes the transistor TR3 conductive.
It is instantaneously discharged via this transistor TR3. As a result, when the input signal is cut off, the L transistor TRI becomes non-conductive, the relay coil X is cut off, and the load current does not flow to the relay contact xb.

However, the charge in the capacitor C4 in the OFF delay circuit 12 is discharged through the resistor R7, and for a predetermined period of time after the input signal is cut off, the potential at the voltage dividing point a3 reaches the voltage dividing point a4.
The output of the differential amplifier OF is held at the ``H'' level, and the conduction of the transistor TR2 is maintained by discharging the charge from the capacitor C3, so that the light emitting element T continues to emit light. By this, the triac Q
is maintained in a conductive state, and current is supplied to load RL via triac Q.

When the electric charge of the capacitor C4 is discharged and the electric potential at the voltage dividing point a3 falls below the electric potential at the voltage dividing point a4 after a predetermined time after the input signal is cut off, the output of the differential amplifier OP becomes "L".
” level, the transistor TR2 becomes non-conductive, the current to the light emitting element T is cut off, the light receiving element J in Fig. 1 is extinguished, and when the trigger current of the triac Q disappears, this triac Q becomes a power source. The arc is extinguished at the zero cross of the voltage, thereby cutting off the current supply to the load M.

In this way, since the load current is turned on and cut off by the triac Q, no arc is generated at the relay contact xb when the load current is turned on and cut off, and the life of the contact can be extended. Since a large current flows to the load RL through the relay contact xb and no load current flows to the triac Q, burnout due to heat generation of the triac Q can be prevented.

Also, ON and OFF of triac Q and relay coil
F control is achieved by the No delay circuit 11 and the OFF delay circuit 12, and does not require adjustment of the contact interval of the relay contacts xb, so existing contact relays can be used, and -1- The ON and OFF timing adjustment of the torque Q and relay coil is done using electronic N.
This can be easily achieved using the O delay circuit 11 and the OFF delay circuit 12.

Furthermore, as shown in FIG.
N. OFF control is easy.

In the figure, B is a varistor for absorbing surges that constitutes an absorber circuit, and a series circuit of a resistor R13 and a capacitor C13 is connected in parallel to this varistor B, and a protection circuit for absorbing surges of the light receiving element J is formed. It consists of R13 is a resistor for protecting the trigger terminal of the triac Q.

Furthermore, in FIG. 3, the power terminals Pi and P2 of the three load circuits 2 are connected to R and S of the three-phase AC power supply E.

When connected to the T phase to drive and control a load RL consisting of one electric motor, it is possible to eliminate variations in the ON operation between the relay contacts xb built into each load circuit 2, so the ON operation of the trigger Q can be There is no variation,
Vibration of motor load RL can be prevented.

In addition, in the embodiment described in -1-, the case was explained in which the load RL is turned on and off using the triac Q as a conductor switching element. There may be.

Furthermore, although a case has been described in which a phototriac coupler consisting of a light emitting element and a light receiving element is used as the triggering element of the TRIAC Q, the triggering element of the TRIAC Q is electromagnetically coupled like a Hall IC. It may be something.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of the load switching device according to the present invention, FIG. 2 is a circuit diagram of an input signal circuit in the load switching device according to the invention, and FIG. 3 is a circuit diagram showing another example of the load switching device according to the invention. 4 is a circuit diagram showing an example of a conventional load switching device, and FIG. 5 is a time chart for explaining the operation of FIG. 4. 1... Input signal circuit, 2... Load circuit, It, I2
...input terminal, T...trigger element (light emitting element),
Pl, P2...power supply terminal, E...power supply, M...
Load, X...Relay coil, xb...Relay contact for energizing, Q...Semiconductor switching element, 11...O
N delay circuit, 12... OFF diddy 1 path. Figure 3 4th 5th

Claims (1)

[Claims] (1) An input signal circuit in which a relay coil and a trigger element are inserted between a pair of input terminals, which are excited by the application of an input signal, and a pair of power supply terminals to which a power supply and a load are connected. In a load switching device comprising a load circuit in which a semiconductor switching element that conducts in response to a trigger signal from the trigger element and a relay contact for carrying load current are connected in parallel, an input signal is input to the input signal circuit. energizes the relay coil after a predetermined delay time from the application of O, and demagnetizes the relay coil when the input signal is interrupted.
The N delay circuit is connected to an OFF delay circuit that energizes the triggering element when the input signal fades and cuts off the energization to the triggering element after a predetermined delay time after the input signal fades. A load switching device characterized by: