JPH07332251A - Protection device for pump motor - Google Patents

Abstract

PURPOSE:To facilitate automatic or manual return of autocut even after protection of autocut operation of the autocut. CONSTITUTION:A heater 20 is arranged at the neutral point 28 of an autocut 13. One circuit 34 of the heater 20 is connected to, for example, a U-phase winding 31 and the other circuit 35 is connected to the power source side of the winding 31 through a no-voltage contact 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for a pump motor, which is exposed to the air, causes a liquid temperature other than the specifications, an overcurrent, a phase loss, and a liquid temperature increase due to a continuous shutoff operation.
The present invention relates to a protection device for a pump motor, which prevents burnout or damage of an electric motor or a pump.

[0002]

2. Description of the Related Art FIG. 3 shows a circuit example of a conventional pump motor protection device. A pump motor 1 having a three-phase induction motor is provided with a conventional thermal-type motor protection device (hereinafter referred to as auto cut) 3 and a slip detection sensor 4. Further, in the control panel 2, an abnormal signal circuit 8
A control unit 10 that receives an abnormal signal from the sensor 4 and sends an open signal to the switch 5 by the open signal circuit 9 is provided. Further, the pump motor 1 is supplied with electric power from a commercial three-phase power source 11 via a switch 5 in the control panel 2. Further, the control unit 10 is supplied with power from the control power supply line 6. Further, regarding the protection operation of the sensor 4, when the sensor 4 is operated by, for example, idling, an abnormality detection signal is sent from the sensor 4 to the control unit 10, and the control unit 10 sends an open signal to the switch 5 to turn on the switch 5. By opening, the power supply to the pump motor 1 is cut off and the pump motor 1 is stopped.

The conventional automatic cut 3 will be described with reference to the simple circuit of FIG. 4. The windings 31 and 3 of the U, V and W phases of the electric motor are described.
It is composed of bimetal switches 25, 26, and 27 connected in a star shape between 2, 33 and a neutral point 28. These switches 25, 26, 27 are the windings 31, 3 of the motor.
When the temperature of 2, 33 rises abnormally, the bimetal warps,
The switches 25, 26 and 27 are separated to cut off the supply of electric power to the electric motor. Conventionally, such an automatic cut 3 has been widely used as a motor protection device for a submersible pump.

However, the conventional pump protection device using the automatic cut 3 merely protects the electric motor by detecting the abnormal temperature rise of the electric motor winding and interrupting the supply of electric current. The conditions that should be protected or stopped as a pump include the above-mentioned exposure operation in the air, liquid temperature other than the specifications, overcurrent, open phase, liquid temperature rise due to continuous shutoff operation, etc., idle rotation, insulation abnormality, overvoltage, A situation such as undervoltage is possible. When the load as the electric motor is small under these circumstances, the operating current of the electric motor is small,
The temperature did not rise enough to warp the bimetal, and protection by Auto Cut 3 was impossible. Therefore, conventionally, the respective sensors are provided, an abnormal signal is sent to the control unit 10 in the control panel 2, and the switch 5 is opened to stop the operation of the pump motor 1.

On the other hand, the applicant has proposed a pump protection device shown in FIG. In the proposal, the heater 20 is provided at the neutral point 28 of the star connection of the three-phase induction motor,
The heater 20 is used as a power source 19 and an external abnormality signal input, and is connected in series with a non-voltage contact 21 that is closed in the event of an abnormality. Then, an external abnormal signal is input, the non-voltage contact 21 is closed, and the heat generated by the heater 20 causes the bimetal switches 25, 26, 27 in the autocut 13 to warp, and the current to the windings 31, 32, 33 is reduced. When the supply is cut off, the three-phase induction motor stops. However, if there is no means for opening the non-voltage contact 21 for inputting the external abnormality signal thereafter, the heater 20 continues to generate heat while the non-voltage contact 21 remains closed, and the automatic cut 13 cannot be restored. . Or, even if it was forcibly restored, there was a problem that the auto cut would immediately work again.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and even if the load of the pump motor is small, the automatic cut is activated by an external abnormality signal input to stop the pump itself. An object of the present invention is to provide a protective device for a pump motor capable of giving a capability, and capable of easily and automatically returning the automatic cut after the protective operation of the automatic cut, even after the protective operation of the automatic cut. To do.

[0007]

According to the present invention, a thermal element contact is provided at a neutral point of a stator winding of a star-connected three-phase induction motor, and the three-phase induction motor has an abnormal temperature rise. When the thermal element contact is activated, the neutral point is opened, and the thermal type motor protection device that shuts off the three-phase induction motor by stopping the supply of current to the three-phase induction motor is built-in. In the pump motor described above, a heater is installed inside or in the vicinity of the thermal electric motor protection device, and one of the cables at both ends of the heater is connected to one of the three-phase windings of the three-phase induction motor. Connect to the coil end on the side of the thermal motor protector, connect the other side of the heater cable to one side of the non-voltage contact that is closed by the input of an external error signal, and connect the other side of the no-voltage contact to the heater cable. The same as the winding that connects one It is connected to the power supply side of the winding.

[0008]

According to the present invention, in the pump motor having the built-in auto-cut protection device that heats the heater by the external abnormal signal input from each sensor or the like to directly activate the automatic cut, the non-voltage contact of the external abnormal signal input is closed. Even if the state remains, the heat generation of the heater can be stopped by shutting off the heater power supply at the same time as the automatic cut protection operation. Therefore, a means for shutting off the heater power supply in accordance with the automatic cut protection operation. There is no problem that the heater continues to generate heat even after the auto-cut protection operation and cannot recover, and the temperature inside the auto-cut gradually decreases and returns to the normal value automatically or manually. Auto cut can be restored easily.

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

In these figures, the parts corresponding to those in FIGS. 3 to 4 are designated by the same reference numerals, and the duplicated description will be omitted.

In FIG. 1, a pump motor 1 including a three-phase induction motor receives power from a commercial three-phase power source 11,
Auto cut 13, heater 12, idling detection sensor 14
And the idling detection sensor 14 is a commercial three-phase power supply 11
Driven by the sensor power supply circuit 7 branched from, the idling detection sensor 14 outputs the detected idling signal to the anomaly signal circuit 8 as an anomaly signal, which causes the heater 12 to generate heat and is heated by the heater 12. When the automatic cut 13 reaches the abnormal temperature rise value, the pump motor 1 is stopped.

2 is different from the conventional auto cut 3 of FIG.
The automatic cut 13 includes a heater 20, and one of the heater cables of the heater 20 is connected to the U-phase winding 31 by the circuit 34.
And the bimetal switch 25, and the other is connected to one side of the non-voltage contact 21 which is closed by an abnormality and is used as an external abnormality signal input by the circuit 35. It is connected to an arbitrary U-phase line on the power supply side of the winding 31.

Next, the operation will be described.

When the non-voltage contact 21 is closed by the input of an external abnormality signal from the idling detection sensor 14, the heater 20 is turned on.
A voltage equal to the voltage across the phase winding 31 is applied, causing the heater 20 to generate heat. When the temperature inside the auto cut 13 rises due to the heat generated by the heater 20 and the temperature rises to an abnormal temperature rise value, the bimetal switches 25, 26, 27 bend back and the winding 3
The neutral point 28 of 1, 32, 33 is opened and the winding 31,
The current flowing through 32 and 33 is cut off and the pump motor 1 is stopped. When the neutral point 28 is opened, the voltage applied to both ends of the U-phase winding 31 becomes zero, and at the same time the voltage applied to both ends of the heater 20 becomes zero, so that the non-voltage contact 21 is closed. Pump motor 1 even in the state
The heat generation of the heater 20 is also stopped with the stop of the above.

As described above, even if the load of the pump motor 1 is small, the automatic protection is activated by the input of the external abnormality signal, so that the pump itself can have the pump stopping ability. Even if the no-voltage contact of the abnormal signal input remains closed, the heat generation of the heater can be stopped by shutting off the heater power supply at the same time as the automatic cut protection operation. , There is no need to take any means to shut off the heater power, and there is no problem that the heater continues to generate heat even after the automatic cut protection operation and cannot recover, and the temperature inside the automatic cut gradually decreases and returns to the normal value. The automatic cut can be easily restored when it is turned on.

Although the heater 20 is connected to both ends of the U-phase winding 31 in the above embodiment, the same effect can be obtained at both ends of the V-phase winding 32 and both ends of the W-phase winding 33.

Further, the sensor for detecting the abnormal signal in the above embodiment is not limited to the idling detection sensor, and prevents the electric motor or pump such as the water temperature rise detection sensor or the overcurrent detection sensor from being burnt or damaged. The same effect can be obtained with various sensors for. Further, the auto-cut in the above embodiment is an auto-reset type that automatically returns when the temperature inside the auto-cut falls back to a normal value, but a manual-reset type auto-cut that manually pushes the return button to return. However, it goes without saying that the same effect can be obtained.

[0018]

Since the present invention is configured as described above, even if the load of the pump motor is small, the automatic cut is activated by the input of the external abnormality signal so that the pump itself has the ability to stop the pump. In the pump protection device that enables the above, even if the non-voltage contact of the external error signal input remains closed, the heater power is shut off by shutting off the heater power supply at the same time as the automatic cut protection operation. Therefore, it is not necessary to take any measures to cut off the heater power supply in connection with the automatic cut protection operation, and there is no problem that the heater continues to generate heat even after the automatic cut protection operation and cannot recover.
When the temperature inside the autocut gradually decreases and returns to the normal value, the autocut can be easily restored automatically or manually.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing details of auto cut shown in FIG.

FIG. 3 is an overall configuration diagram showing an example of a conventional device.

4 is a drawing corresponding to FIG. 2 in FIG. 3;

FIG. 5 is a drawing corresponding to FIG. 2 of the device previously filed by the applicant.

[Explanation of symbols]

 1 ... Pump motor 2 ... Control panel 3 ... Auto cut 4 ... Idling detection sensor 5 ... Switch 6 ... Control power supply line 7 ... Sensor power supply circuit 8 ...・ Abnormal signal circuit 9 ・ ・ ・ Open signal circuit 10 ・ ・ ・ Control unit 11 ・ ・ ・ Three-phase power supply 12 ・ ・ ・ Heater 13 ・ ・ ・ Automatic cut 14 ・ ・ ・ Slip detection sensor 19 ・ ・ ・ Power supply 20 ・..Heater 21 ... Non-voltage contact 25 ... Bimetal switch 26 ... Bimetal switch 27 ... Bimetal switch 28 ... Neutral point 31 ... Winding (U phase) 32 ... Winding Wire (V phase) 33 ... Winding (W phase) 34, 35 ... Circuit

Claims (1)

[Claims] 1. A thermal element contact is provided at a neutral point of a stator winding of a star-connected three-phase induction motor, and the thermal element contact operates when the temperature of the three-phase induction motor rises abnormally. Then, the neutral point is opened so that the current supply to the three-phase induction motor is cut off to stop the three-phase induction motor. A heater is installed inside or in the vicinity of the protection device, and one of the cables at both ends of the heater is connected to the coil end of the thermal motor protection device side of one of the three-phase windings of the three-phase induction motor. Connected to one side of the non-voltage contact that is closed by an external abnormality signal input, and the other side of the non-voltage contact is in the same phase as the winding to which one of the heater cables is connected. Connection to the power supply side of the winding Characteristic pump motor protection device.