JPS6031435Y2 - Double voltage switching device for single-phase induction motor - Google Patents

Description

[Detailed Description of the Invention] The present invention provides that the applied power supply voltage of a single-phase induction motor is, for example, 10
The present invention relates to a device that automatically switches two divided main windings into series and parallel depending on the level of the power supply voltage when there is a dual voltage such as 0V and 200V.

Conventionally, in order to cope with double voltage, the main winding of a single-phase induction motor was divided into two parts, and the main windings were connected in series and parallel using connectors depending on the level of the power supply voltage.

However, with this manual switching method, if there is a mistake in the switching connection of the connector for the power supply voltage, the main winding etc. may be instantly burnt out, or the single-phase induction motor may not operate due to the low applied voltage. be.

The present invention has been devised in view of these points, and one embodiment of the present invention will be described below based on the drawings.

In the drawing, the main windings 1 and 2 are divided into two parts, and one of the main windings 2 is connected in parallel with a series circuit of an auxiliary winding 3 and a capacitor 4.

The main windings 1 and 2 are connected in parallel via first and second relay switches 5 and 6, and in series via a third relay switch 7. Switched and connected in parallel.

8 is a control relay that controls the relay switch,
It is rated for high power supply voltage.

The control relay is connected to the power supply terminal 11.12 through a parallel circuit of a fourth relay switch 9 and a positive temperature coefficient thermistor 10 controlled by the control relay.

A dual voltage power source 13 is connected to the power source end.

The first and second relay switches 5, 6 are normally open switches, and the third and fourth relay switches 7.9 are normally open switches.

In the drawings, a solid line state of each relay switch indicates a low voltage state of the power source 13, and a broken line state indicates a high voltage state.

When the power source 13 is at a high voltage (for example, 200 V), approximately the rated voltage is applied to the control relay 8 and it operates normally, and each relay switch is switched to the state shown by the broken line.

Therefore, the main windings 1 and 2 are connected in series via the third relay switch 7, and are connected to the high power supply voltage, so that the single-phase induction motor operates normally.

At this time, the positive temperature coefficient thermistor 10 is short-circuited by closing the fourth relay switch 9, so that approximately the rated voltage is applied to the control relay 8 and it is self-maintained.

Next, when the power supply voltage is a low voltage (for example, toov), only approximately half the rated voltage is applied to the control relay 8, so the control relay does not operate normally, and each relay switch is connected to the solid line. The condition remains.

Therefore, the main windings 1 and 2 are connected in parallel via the first and second relay switches 5 and 6, and are connected to a low power supply voltage, so that the single-phase induction motor operates normally.

Generally, in the control relay 8, the regular rated excitation current flows and the coil temperature is set below a certain value while the movable contact plate for driving the opening and closing of the contacts is firmly attracted to the iron core of the control relay. Therefore, while the control relay is in operation (corresponding to when the power supply voltage is high in the present invention), it can be used without any problem.

Further, the minimum guaranteed starting voltage of the control relay 8 is approximately 75 to 80% of the rated voltage, and does not operate at 50% voltage.

Therefore, when the voltage is low, the fourth relay switch 9 connected in parallel to the PTC thermistor 10 is in the open state shown by the solid line, and the control relay 8 is energized via the PTC thermistor 10.

Due to self-heating of the positive temperature coefficient thermistor 10, the resistance value of the thermistor increases rapidly, so the amount of current applied to the control relay 8 is reduced, the temperature rise of the control relay is reduced, and burnout of the control relay is prevented.

If the positive temperature coefficient thermistor 10 is not present, only approximately 50% of the rated voltage will be applied to the control relay 8, so the control relay will not operate and the movable contact plate of the control relay will not be reliably attracted to the iron core. Therefore, due to the presence of air, a normal magnetic circuit cannot be established, and a large excitation current flows, increasing the temperature of the coil.

Therefore, if the control relay is left in this state for a long period of time, the temperature of the control relay may rise and the coil of the control relay may burn out.

As described above, according to the present invention, when the power supply has dual voltage, the two main windings are automatically switched to series and parallel depending on the level of the power supply voltage. It is possible to save time and effort in switching connections using connectors depending on the voltage level, and to prevent switching errors from occurring.

In addition, the control relay is connected to the power supply terminal through a parallel circuit of a normally open relay switch and a positive thermistor controlled by the control relay, so when the power supply is low voltage, the presence of the positive thermistor causes low voltage and large current. It is possible to prevent the flow from flowing to the control relay, and it is possible to prevent the control relay from burning out.

[Brief explanation of drawings]

The drawing is an electrical circuit diagram showing an embodiment of the device according to the present invention. 1.2... Main winding, 5, 6.7... Relay switch, 8... Control relay 9...
...Normally open relay switch, 10...Positive characteristic thermistor.

Claims (1)

[Scope of utility model registration request] The control relay of the relay switch that switches the two-divided main winding in series and parallel depending on the high and low power supply voltages is rated for approximately high power supply voltage, and the normally open relay switch and positive temperature coefficient thermistor controlled by the control relay are connected in parallel. A double voltage switching device for a single-phase induction motor, characterized in that the control relay is connected to a power supply terminal via a circuit.