SU1354325A1 - Arrangement for protecting three-phase electric motor from phase break - Google Patents

Abstract

This invention relates to electrical engineering, in particular, to relay protection. The purpose of the invention is to increase the reliability of operation and use to protect the drive. balancing machine. This is achieved by the fact that when starting the drive, contact 8 is closed. A coil 18 is supplied with current from the source of the voltage 19. When a non-phase supply mode of the electric motor 3 occurs, a voltage appears at the output of the single-phase rectifier 16. Diode 20 is locked, an obstruction is pro-. current flow on the winding 18 current relay. Terminal 8 opens in the winding circuit 7 of the switching device. The motor is disconnected from the network. 1 hp f-ly, 1 ill. (Ls

Description

This invention relates to a relay protection technique for electric drives and can be used in electric drives of balancing machines.

The purpose of the invention is to increase the reliability of operation, to use a balancing machine with protection as well as with a working neutral wire to protect the electric drive.

The drawing shows a diagram of the electric balancing machine.

The electric drive of the balancing machine contains a series-connected switching device 1 connected to the mains, a thermo-bimetallic relay 2, an asynchronous electric motor 3 with an electromagnetic brake 4 and an electromagnet 5 controlling the brake, the circuit of which includes contact 6 of the switching device 1 connected in series with the switching control winding 7 , closing contact 8 of a DC relay, contact 9 of a thermo-bi-metallic relay 2, control element Start 10, shunted with a closing end act commuting present apparatus 11 and the element 12 stop.

In addition, the electric drive contains 30 electric motors from phase failure.

capacitors 13-15, each of which is connected to the terminals of the electric motor by a second terminal, and the first ones form a zero point connected to the first input of a single-phase rectifying bridge 16, the second input of which is connected to the neutral protective conductor 17 by a direct current relay, the first the output of the winding 18 of which is connected to the positive pole of the source 19 of the reference voltage, the second to the anode of the diode 20, the cathode of which is connected to the negative pole of the source 19 of the reference voltage and to the negative output of one znogo vshr mitel- Nogo bridge 16, the positive terminal of which is connected to the movable contact of the variable resistor 21. The Executive relay contact 8 d.c. included in the control winding 7 of the switching circuit unit. The reference voltage source 19 is galvanically coupled to the mains voltage. One of the terminals of the electric motor is connected to ground through the disconnecting contact of the switching device.

When starting the motor, contact 8 of the DC relay is closed

since a current from the source 19 of the reference voltage flows through its winding 18. In the case of a non-phase-phase power supply of the electric motor 3, a voltage appears at the output of the single-phase rectifying bridge 16, which is applied to the cathode of the diode 20 through the variable resistor 21 and prevents it from flowing through the coil 18 of the direct current relay . The latter opens its contact 8 in the winding circuit 7 of the control of the switching apparatus and the electric motor 3 is disconnected from the network.

The opening contact 22 closes the discharge circuit of the capacitors 13 - 15 when the motor is switched off.

Thus, the proposed electric drive with a protection unit is more reliable and safe, and its circuit can be used in a set with zero working or protective conductors.

Claims (2)

Claim 1. The protection device is a three-phase switching device, the power contacts of which are intended to be connected to the phase wires supplying the electric motor, thermo-bimetallic relays intended to turn on the end phases in series with the indicated contacts, the control circuit of the switching device connected to the source of operating voltage is view of the consecutively connected buttons Stop, Start, which is shunted by the auxiliary contact of the switching device, which opens the contact and thermo-bimetallic relays and control windings, a protection unit consisting of three capacitors, the first terminals of which form a zero point connected to the first input of a single-phase rectifying bridge, a reference voltage source, a direct current executive relay, a diode, a ballast resistor and a variable A resistor, characterized in that, in order to increase the reliability of operation and use to protect the electric drive of the balancing machine with both a protective and a working neutral wire, the second terminals 31354325 Capacitors are designed for non-single phase rectifier bridge, mediocre connection to the clamp positive that is connected the protected motor, the second with a movable contact variable input single-phase rectifier through a resistor, and the closing relay contact the ballast resistor is connected to zero-dc current and is connected to the circuit by a twisted wire, the first terminal of the winding of the control coil of the switching current-operating relay. connected to the positive pole of the voltage source, the second is -jg 2. The device according to claim 1, 1 and 2 with the anode of the diode, the cathode of which is transacted by the fact that the variable resistor is connected to de-energize the source the integral pole of the source of the support voltage is made in the form voltage and with a negative output of an additional power source.