SU1356112A1 - Arrangement for protecting three-phase electric motor from two-phase work - Google Patents

Abstract

This invention relates to electrical engineering, in particular, to relay protection. The purpose of the invention is to increase reliability. If the engine 9 fails during any phase, the source phase — the motor phase is blocked by diodes 16 and 17, the thyristor 12 is locked, the relay coil 10 de-energizes and its contact 11 opens, de-energizes the relay 5. Contacts B, 18 relays open and disconnect engine 9 from the network. Engine 9 is not restarted until the fault is eliminated. 1 il. (L with N3

Description

 one

The invention relates to electrical engineering and can be used to protect three-phase asynchronous electric motors of commercial and technological equipment from operation on two phases and three-phase electric motors used in other branches of the national economy.

The purpose of the invention is to increase reliability.

The drawing shows a functional diagram of the device,

In the phases of networks 1, 2 and 3, the main fuses 4 are installed. The coil of the power relay 5 is connected to the first and second phases by means of leads through the Start 6 and Stop 7 buttons. The power contacts 8 are connected to each phase of the network between the fuses 4 and the motor winding 9,

Phase integrity control unit

T, consisting of a relay 10 direct current, a block-contact 11, a thyristor 12, a resistor 13, a diode 14, a capacitor 15, is turned on so that the cathode of the thyristor is the first output of the aforementioned unit, the anode is connected to one output of the relay 10 constant with a parallel-connected capacitor 15, the second output of the relay is the second output of the network phase integrity control unit, the control electrode of the thyristor 12 is connected to a series-connected resistor 13, a diode 14, the second output of the resistor is the third output of the said block, l integrity phase network connected to each phase of the power line between the power contacts of the power relay 8 and 5 obmbtkami motor 9 and the contacts 11, the relay 10 connected in parallel with the start button 6.

The number of phases of the network additionally introduced the first power diode 16, a circuit of series-connected second power diode 17, the second power contact 18 power relay 5 and

the second fuse 19, with 50 second terminal of the control unit; the first power diode 16 is provided with leads for connecting in series with the winding of the electric motor 9 opposite the thyristor electrode 12, the second power diode 17 is equipped with leads for connecting according to the first power diode 16, the second lead of the second fuse 19 is connected to the first fuse from the side of the network.

the integrity of the network phases; the control electrode of the thyristor is connected to a series-connected diode and a resistor; the second terminal of the resistor is the third terminal of the said block, characterized in that, in order to increase reliability, the block of phase integrity monitoring of the network with terminals for each

The device works as follows.

When the Start button 6 is pressed, the winding of the relay 5 is powered, the power contacts 8 and 18 of which are closed, the thyristor 12 is periodically opened and due to the capacitor 15

contact 11 of the relay is in the closed state, by shunting the start button 6,

Engine 9 is locked.

If the engine 9 fails during any phase, the source phase — the motor phase is blocked by diodes 16 and 17, the thyristor 12 is locked, the relay coil 10 de-energizes and its contact 11 opens, de-energizes the relay 5, Relay contacts 8 and 18 open and disconnect engine 9 from the network. Engine 9 is not restarted until the fault is eliminated.

In this way, protection against operation in two phases is ensured, and starting currents are reduced when restarted, which allows for increased reliability of operation of the installation as a whole.

Claims (1)

Invention Formula 1, Device for protecting a three-phase electric motor from two-phase operation, containing fuses, equipped with leads for connecting to each phase of the network, a magnetic starter, the coil of which is equipped with leads for connecting to the first and second phases of the network through successively connected Stop buttons and, the power contacts are intended to be connected to each phase of the network between the fuse and motor winding, the phase integrity control unit of the network with a thyristor, the cathode of which is the first output of the aforementioned unit, the anode is connected to one output of the DC relay with a parallel-connected capacitor 5 another the output of the relay is50 the second output of the control unit the integrity of the network phases; the control electrode of the thyristor is connected to a series-connected diode and a resistor; the second terminal of the resistor is the third terminal of the said block, characterized in that, in order to increase reliability, the block of phase integrity monitoring of the network with terminals for each 31356112. four In the phase of the mains supply, an intermagnet starter and the second one are connected by the preset contacts of the magnetic starter, with the first power supply the motor and windings of the motor, the diode is provided with leads for connecting the contacts of the direct current relay in series with the winding of the motor included parallel to the start button. 5 motor to the first power terminal 2, the Device-according to claim 1, about the TL and -tact counter electrode of the thyristor, so that the second power diode is equipped with the output phase of the network additionally introduced per-connection for connection with the first gray power diode and the circuit from a second diode, the second output of the second, respectively, connected second power 0-fuse is connected to the first diode, the second power contact-fuse from the network side.