SU1365231A1 - Arrangement for protection from no-voltage mode in one of supply phases of three-phase induction motor - Google Patents

Abstract

The invention relates to electrical engineering and is intended for the protection of electric motors operating in industry and agriculture. The purpose of the invention is to increase the reliability of the electric motor and capacitors in the non-phase-phase mode of the supply network by preventing

Description

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short-circuit to ground through a faulty power line, increasing the efficiency of using capacitors by continuously compensating for reactive power in the power network, regardless of the duration of the switching on of the electric motor, providing protection against switching and lightning overvoltages and improving electrical safety by preventing voltage from being transmitted to the malfunctioning power line from an electric motor operating in a capacitor mode. In the event of the disappearance of a voltage in one of the phases of the mains supply, the corresponding current and intermediate relays are de-energized, the electric motor The invention relates to electrical engineering and is designed to protect electric motors operating in industry and agriculture.

The purpose of the invention is to increase the reliability of the electric motor and capacitors in the case of an incomplete phase mains supply by preventing short circuits to ground through the power line, increasing the efficiency of using capacitors by continuously compensating for the reactive power in the mains supply jHe depending on the duration of the motor starting, ensuring protection against switching and thunderstorm overvoltages and increased electrical safety by preventing the transfer of voltage to the faulty line power supply from an electric motor operating in capacitor mode.

The drawing shows a diagram of the device.

A device for protection against power failure in one of the phases of the power supply network of a three-phase asynchronous electric motor 1 connected to the power supply network through the power contacts 2 of the switching apparatus contains three current relays 3-5 and three capacitors 6-8, and the current coils 1 is switched to condenser power mode. The open contact of the current relay breaks the power supply circuit of the faulty phase, disconnecting it from the corresponding capacitor. In this way, the possibility of a short circuit to earth through the faulty supply line is prevented, and the electric motor 1 is operated reliably in capacitor mode. When the supply voltage is restored, the corresponding intermediate and current relays are triggered, and the electric motor 1 is switched to the normal power supply mode, in which the capacitors compensate for the reactive power in the supply mains. 1 il.

the output relays have leads designed to turn on each winding. successively into the supply line of the corresponding phase of the electric motor 1 by the first output of the winding in the direction of the electric motor, and the second in the direction from the power supply network.

The first output of the opening contact (3.1) is connected to the first terminal of the winding of the current relay, for example, the relay 3 connected to the power line of this phase (A) of the electric motor. this relay, the second output of which is connected via the corresponding capacitor (6) to the first output winding of the current relay (4), which is intended to be connected to the power line of the subsequent phase (B) of the electric motor.

Open contacts 3.1-5.1. Current relays 3-5 are shunted by each respective chain, consisting of series-connected make contacts in 3.2-3.4, 4.2-4.4, 5.2-5.4 of three current relays 3-5. In the device there are three intermediate relays 9–11 voltages each with one closing contact 9.1–11.1, and the current relays 3-5 are equipped with each additional closing 3.5–5.5 and opening 3.6–5.6 contacts.

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The second terminal of the winding of each current relay 3-5 is connected to the first output of the corresponding chain, from the parallel connected additional closing contact, for example, contact 3.5 of this current relay 3 and closing contact 9.1 of the corresponding intermediate relay 9, The second terminal of this chain is to connect to power supply and is connected via an additional disconnecting contact 3.6 of this current relay 3 with the first winding terminal of the corresponding intermediate relay 9, the second terminal of which serves to connect to zero conductor network. The first pins of the current relays 3-5 are designed to connect to the first pins of the power contacts 2 of the switching device, the second pins of these contacts connected to the phase terminals of the electric motor 1.

The device works as follows.

When the voltage at the inputs A, B, and C is closed, the power contacts 2 of the switching device in the windings of the current relays 3-5 flow the operating current of the electric motor. At the same time, contacts 3.1-5.1 and 3.6-5.6 are once-closed, while contacts 3.2-3.4, 4.2- 4.5, 5.2-5.5 are closed. Capacitors 6-8 are triangular and compensate for the reactive power in the network.

When the power contacts 2 of the switching device are open, the operating current of the capacitors 6-8 flows through the windings of the current relays 3-5, and the device operates in the same way.

When the voltage disappears in one of the phases of the mains supply, for example, phase C, current relay 5 and relay 11 de-energize, contacts 5.1-5.6 close and contacts 5.2, 5.3, 5.4 and 11.1 open.

The motor 1 is switched to condenser mode. The open contact 5.5 of the relay 5 breaks the circuit of the power line of phase C, in which the phase-shifted voltage of the capacitor 8 appears, thereby protecting against possible electric shock. In addition, the operating modes of the electric motor 1 and the capacitor 8 are improved, since other power consumers that are connected to (or

The opening of contact 5.5 of the relay 5 is disconnected from the capacitor 8 and does not prevent further operation of the electric motor 1 in the capacitor mode. Similarly, the possibility of a short-circuit of the capacitor 8 to earth through the faulty power line of phase C is prevented. After the voltage in the power line of phase C is restored, relay 11 is activated, contact 11.1 is closed, and then relay 5 is triggered.

Elezstrodvigatel 1 continues to work in normal mode power.

With open .force contacts 2 of the switching apparatus and non-phase-line modes of the network, the device operates in the same way.

The positive effect created by the invention is to increase the reliability of the electric motor in the case of incomplete mains supply, improved electrical safety and efficient use of capacitors.

Claims (1)

Invention Formula five 0 five 0 five A device to protect against voltage disappearance in one of the phases of the three-phase asynchronous motor power supply network connected to the power supply network through the power contacts of the switching device containing three current relays and three capacitors, and the windings of the current relays have terminals intended for switching each winding in series to the line supplying the corresponding phase of the electric motor with the first winding lead in the direction of the electric motor, and the second to the power supply side, to the first winding lead of the current relay is switched on The first output contact of this relay is connected to the power line of this motor phase, the second output of which is connected to the first winding terminal of the current relay through the corresponding capacitor, which is connected to the power line of the subsequent motor phase, and the current-relay contacts are shunted each corresponding chain consisting of. sequentially connected make contacts of three current relays, characterized in that, in order to improve the operation of the electric motor and capacitors in the incomplete phase supply mode by preventing short circuits to ground through a faulty power supply lithium, by continuously compensating for reactive power in the power supply network, regardless of the durability of switching on the motor, providing protection against switching and thunderstorm overvoltages and improving electrical safety by preventing the voltage from being transferred to the faulty power line from the electric motor operating in capacitor mode, three intermediate voltage relays each with one make contact are inserted into the device, and each additional make and break contacts are supplied with the second relay the relay is connected to the first output of the corresponding chain, which consists of an additional make contact in parallel of the current relay and the closing contact of the corresponding intermediate relay, the second output of which is intended to be connected to the power supply network and is connected via an additional normally open contact of the current relay with the first output winding of the corresponding The intermediate intermediate relay, the second terminal of which is intended to be connected, to the zero conductor of the network, and the first terminals of the windings of the current relays are intended to be connected to the first terminals of the power contacts of the switching apparatus, the second terminals of these contacts are connected to the terminals of the phase windings of the electric motor.