JPH0534912B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a control circuit that starts and stops a load using an electromagnetic switch, and the present invention provides a control circuit that starts and stops a load using an electromagnetic switch. This relates to a circuit that can restart a load and continue operation.

[Conventional technology]

FIG. 3 is a circuit diagram of a device for starting and stopping an electric motor using, for example, an electromagnetic switch. In the figure, 1 is a molded circuit breaker that protects the circuit, 2 is an electromagnetic switch, 2a is an auxiliary contact of this electromagnetic switch 2,
Reference numeral 3 designates a thermal relay for detecting overload of the motor, 4 a motor serving as a load, 5 a normally open pushbutton switch for starting, and 6 a normally closed pushbutton switch for stopping.

Next, the operation will be explained. When the push button switch 5 is closed, the coil of the electromagnetic switch 2 is energized, the main contacts are brought into conduction, and the motor 4 is started. At this time, the auxiliary contact 2a of the electromagnetic switch 2 connected in parallel to the pushbutton switch 5, which is a normally open contact, is closed, so the electromagnetic switch 2 is self-held, and even if the pushbutton switch 5 is opened, the electric 4 continues driving. When the push button switch 6 is opened during operation of the electric motor 4, the coil of the electromagnetic switch 2 is deenergized, the main contact is opened, and the electric motor 4 is stopped.

If the electric motor 4 is currently operating and the auxiliary contact 2a of the electromagnetic switch 2 is closed and the coil is kept energized, if the power supply voltage drops or a power outage occurs, the coil voltage of the electromagnetic switch will drop. Then, the electromagnetic switch 2 becomes open, and the auxiliary contact 2a also opens. Therefore, even if the power supply voltage is restored again, the coil of the electromagnetic switch 2 is not excited, and the motor 4 continues to be stopped.

[Problem that the invention seeks to solve]

Since it is configured more like a conventional electromagnetic switchgear, when the power supply voltage is restored after a short power outage, the load equipment is in a stopped state, and the load equipment must be pressed again to resume operation. Button switch 5 must be closed. Depending on the type of load, there may be no effect on operation even if a short power outage occurs, and it is desirable for such loads to restart automatically when power is restored, but restarting is not recommended. It is necessary to press the push button switch 5 again in order to operate the machine, which is cumbersome to operate, and even in the event of a short power outage, the operation may be interrupted for a long time. There were problems such as the possibility of adverse effects.

This invention was made to solve the above-mentioned problems, and aims to provide an instantaneous restart device that can automatically restart a load when power is restored after a short power outage. purpose.

[Means for solving problems]

In order to apply a predetermined DC voltage to the relay coil, a resistor, a diode, and a series circuit of the relay coil are connected in parallel to the coil of the electromagnetic switch, and the diode is connected between the terminals of the relay coil in a direction that allows charging of the capacitor. Connect a series circuit of the above capacitor with the above capacitor, and when the power is lost, the charge of the above capacitor is transferred to the resistor, diode, normally open contact of the relay,
A circuit is formed to discharge electricity through the normally closed contact and the relay coil, and the other normally open contact of the relay is connected in parallel to the auxiliary contact of the electromagnetic switch to excite the relay for a predetermined time when a power outage occurs. This allows the state to be maintained.

Furthermore, the series circuit of the resistor, diode, and relay coil has an indicator light.

[Effect]

In this invention, when the power supply fails during load startup, current is discharged from the capacitor that was charged during load startup, and the current is transmitted through the normally open and normally closed contacts of the resistor, diode, and relay. The current flows through the relay coil, continuously energizing the relay coil. Therefore, the other normally open contacts of the relay coil connected in parallel to the auxiliary contacts of the electromagnetic switch remain closed. When the power outage is restored, current flows from the power supply to the other normally open contacts, energizing the electromagnetic switch and automatically restarting the stopped load. In addition, since the discharge circuit is equipped with a normally closed contact for stopping the load and a normally open contact for the relay coil, if the normally closed contact is used to stop the load during an uninterrupted power outage, the normally open contact of the relay coil will cause the relay coil to stop using the capacitor. The load stops instantly.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 to 6 are the same parts as the same symbols in FIG. 3 showing the conventional example, and 11 is a relay;
11a and 11b are normally open contacts of the relay 11 (hereinafter referred to as
12 is a voltage drop resistor for applying a predetermined voltage from the power supply voltage to the relay 11 and the capacitor 13; 14 is a diode for applying a half-wave rectified DC voltage to the relay 11 and the capacitor 13; Reference numeral 15 denotes a blocking diode to prevent the electric charge of the capacitor 13 from directly discharging to the relay 11, 13 a capacitor that accumulates electric charge to excite the relay 11 during a power outage, and 16 a blocking diode to prevent the electric charge of the capacitor 13 from discharging directly to the relay 11. 11 is a resistor for obtaining a discharge time; 17 is a blocking diode for preventing direct charging of the capacitor 13 from the power supply;
b is a relay 1 for disconnecting the coil of the relay 11 from the capacitor 13 when the normally closed push button switch 6 for stopping is opened and the electromagnetic switch 2 is dropped.
A contact 11a is a contact of a relay 11 that excites the coil 2 of the electromagnetic switch when the power is restored.

Next, the operation will be explained. When the push button switch 5 is closed, the coil 2 of the electromagnetic switch is energized, the main contacts are brought into conduction, and the motor 4 is started. At the same time, the auxiliary contact 2a of the electromagnetic switch 2 is closed and self-maintained, and the push button switch 5, which is a normally open contact, is closed.
Even if the circuit is opened, the operation of the electric motor 4 continues. Furthermore, the relay 11 is excited with a half-wave rectified voltage through a resistor 12 and a diode 14, and its output closes the contacts 11a and 11b, and the capacitor 13 is charged to a predetermined voltage through the resistor 12 and diodes 14 and 15. .

When the stop push button switch 6 is opened during operation of the electric motor 4, the excitation of the coil 2 of the electromagnetic switch is released, and its contacts 11a and 11b are also opened. As a result, the relay 11 is disconnected from the capacitor 13, the main contact of the electromagnetic switch 2 is opened, and the motor 4 is instantaneously stopped by the falling time of the electromagnetic switch 2. Furthermore, since the contact 2a and the relay contact 11a are also opened, the electric motor 4 maintains the stopped state even if the normally closed contact of the push button switch 6 is closed again.

Here, if a power outage occurs while the electric motor 4 is operating, the coil voltage of the electromagnetic switch 2 disappears, and the main contact and the auxiliary contact 2a are opened. However, the charge accumulated in the capacitor 13
Resistor 16, diode 17, relay contact 11b, pushbutton switch 6, and relay 1 from the positive terminal of
1, the coil of relay 11 continues to be energized by this charge, and the formation of other discharge circuits is blocked by diodes 15 and 17. The current in the coil 11 is attenuated by a time constant determined by the capacitance of the capacitor 13, the resistor 16, and the coil resistance of the relay 11.
When the holding current becomes less than or equal to , the relay 11 is turned off and the contacts 11a and 11b are opened. Therefore,
After a power outage, relay 11 is activated due to the charge in capacitor 13.
When the power is restored while the motor is kept in an excited state, the coil of the electromagnetic switch 2 is excited through the contact 11a and the pushbutton switch 6, and the motor 4 automatically starts operating again. On the other hand, when the power is restored after the holding of the relay 11 is released, the excitation circuit of the coil of the electromagnetic switch 2 has disappeared, and the motor 4 remains in a stopped state even if the power is restored.

Further, as another embodiment, a light emitting diode for displaying operation is connected in series with the coil of the relay 11, as shown in FIG. In the figure, reference numeral 18 is a light emitting diode for display.The power source is the excitation current of the relay 11 due to the power supply voltage or the charge of the capacitor, and the light emitting diode 18 emits light during the holding time of the relay 11 during operation or during a power outage. Checks and timed checks can be easily performed.

Although the above embodiments have been described using an electric motor as the load, the load is not limited to this, and the present invention can be similarly applied to other electric devices, and the same effects as described above can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, a charging circuit and a discharging circuit are provided for the charge of the capacitor, and the relay is energized for a predetermined period of time in the event of a power outage to maintain the electromagnetic switch in a restartable state. , when a short power outage occurs and the power is restored within a predetermined time, the load can be automatically restarted, improving operability. Furthermore, the discharge circuit is equipped with a normally closed contact for stopping the motor and a normally open contact for the relay, so if the load is stopped using an external normally closed contact during an uninterrupted power outage, the normally open contact of the relay disconnects the relay from the capacitor. It can be disconnected, and therefore the load can be stopped instantaneously within the time it takes for the electromagnetic switch to fall, without being affected by restarting by a relay. Further, since a resistor is provided in the discharge circuit, the accuracy of the holding time is improved, and even if the circuit voltage changes, it can be easily coped with by simply changing the resistance value of the voltage drop resistor. Furthermore, there is an effect that the operation of the relay can be displayed more directly.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an instantaneous restart device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment of the invention, and FIG. 3 is a circuit diagram showing a conventional starting device. be. In the figure, 2 is an electromagnetic switch, 4 is an electric motor, and 1
2 and 16 are resistors, 14, 15, and 17 are diodes, 13 is a capacitor, and 11 is a relay. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In an electromagnetic switch that forms a self-holding circuit with auxiliary contacts, starts a load with a normally open contact, and stops the load with a normally closed contact, a predetermined DC voltage is applied to a relay coil. In order to apply voltage, connect a series circuit of a resistor, a diode, and the above relay coil in parallel to the coil of the electromagnetic switch, and connect the series circuit of the diode and the above capacitor in a direction that allows charging of the capacitor between the terminals of the relay coil. When power is lost, the charge on the above capacitor is transferred to the resistor, diode, normally open contact of the relay,
A circuit is formed to discharge electricity through the normally closed contact and the relay coil, and the other normally open contact of the relay is connected in parallel to the auxiliary contact of the electromagnetic switch to excite the relay for a predetermined time when a power outage occurs. An instantaneous power failure restart device characterized by being able to maintain a state. 2. The instantaneous restart device according to claim 1, wherein the series circuit of the resistor, diode, and relay coil has an indicator light.