SU1557622A1 - Device for protection of three-phase electric motor from emergency conditions - Google Patents

Abstract

The invention relates to electrical engineering, in particular, to devices for protecting electrical consumers from damage during emergency operation (overload, phase failure, unacceptable asymmetry and lowering of supply currents and voltages). The aim of the invention is to increase the efficiency of functioning by implementing an automatic correction of protection devices. When an unacceptable increase in the current of the power consumer 53 increases the current of the secondary winding of the current transformer and the maximum current relay 4 (overload relay) is triggered /, opens its contact 8 in the relay 6 circuit. At the same time, with the time delay determined by the discharge of the capacitor 34, the relay 6 turns off your contact 50 in the circuit of the magnetic actuator 47 and disconnecting the power consumer 53. With an unacceptable decrease in the power consumer the minimum current relay 6 is activated, disconnecting the power consumer. The settings for the operation of the minimum current relays 19 to 22 correspond to specific power consumption classes. When replacing one power consumer with another one with a lower class of power, the current in the secondary winding of current transformer 1 triggers the minimum current relay 19 and shunt resistances 11 and 24 in relay circuit 4 and 6 and maintain relative / current protection settings / these relays. 1 il.

Description

one

(21) 4456964 / 24-07. (22) 18.07.88 (46) 15.04.90, Bul, No. 14

(71) Azerbaijan Energy Research Institute

them. I.G.Esmana

(72) R.N. Ahmedov. A.D.Akhmedov, E.A.Ismailova and N.B.A.Ismailov (53) 621.316.925 (088.8)

(56) USSR Copyright Certificate No. 936180, Clo H 02 H 7/08, 07/10/80.

(54) DEVICE FOR ELECTRICAL CONSUMER PROTECTION AGAINST DAMAGE (57) The invention relates to electrical engineering, in particular, to devices that protect electrical consumers from damage during emergency operation (overload, phase failure, unacceptable asymmetry and decrease in supply currents and voltages). The aim of the invention is to increase the efficiency of operation by implementing automatic correction of protection settings. With an unacceptable increase in the current of the power consumer 53, the secondary current of the trans current transformer increases and the maximum current relay 4 (overload relay) is triggered, opens its own contact 8 in relay circuit 6, and with a time delay determined by the discharge of the capacitor 34, o is turned off relay 6, open its contact 50 in the circuit of the magnetic actuator 47 and 1 disconnect the power consumer 53. With an unacceptable reduction in the current of the electrical consumer, the minimum is 15

current relay 6, disconnecting the power consumer. The settings for the operation of the minimum current relay 19-22 correspond to specific power consumption classes. When replacing one power consumer with another with a lower power class, a decrease in current in the secondary winding of current transformer 1 triggers minimum current relay 19 and shunt resistances 11 and 24 in relay circuit 4 and 6 and maintains relative (relative to the nominal current of the power consumer) protection settings these relays. 1 il.

The invention relates to electrical engineering, in particular, to a device of protection of an electro-consumer from damage during emergency operation (overload, phase failure, unacceptable asymmetry of supply currents and voltages, unacceptable reduction of currents and voltages).

The purpose of the invention is to increase the efficiency of functioning by implementing automatic correction of protection settings.

The drawing shows a schematic diagram of the proposed device.

The device contains a current T-transformer 1, connected to the circuit of one of the phases of the supply circuit, the first 2 and second 3 diodes, the maximum relay

4current and first 5 and second 6 minimum current relays, the first terminals of the windings of which through disconnecting contacts 7, 8 and 9, respectively, maximum relay 4 current, first

5 and the second 6 minimum current relay are connected to the first output of the secondary winding of the current transformer, shunted by the first diode 2, the second output winding of the relay 4 through the co-limiting resistances 10 and 11-14, the last of which are bridged by disconnecting contacts 15-18 22 minimum currents, connected to the cathode of the second diode 3. The second output of the winding of the relay 6 through current-limiting resistances 23 and 24-27, shunted by disconnecting contacts 28-31 of the relay 19-22, is also connected to the cathode of the diode 3, the anode of which is connected to

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the connection point of the cathode of the first diode 2 and the second output of the secondary winding of the current transformer 1, the second output of the relay 5 winding through a resistor 32 is connected to the cathode of the diode 3. The windings of the first 5 and second 6 relays and in series with them limiting resistances 32 and 23-27 are bridged respectively capacitors 33 and 34.

0botki additional relays 19-22 through parallel-connected disconnecting contacts 35-38 of their relay and disconnecting contacts 39-42 of the first 5 minimum current relays and current-limiting resistors 43-46 are connected between the anode of the first 2 and the cathode of the second 3 diodes.

The winding of the magnetic actuator 47 through the contacts 48 of the Start button, shunted respectively by the closing contacts 49 of the magnetic actuator and 50 of the second minimum current relay 6, and the Stop button 51 are connected to two phases of the mains supply.

The power contacts 52 of the magnetic starter 47 are included in the phases of the network supplying the power consumer 53.

The device works as follows

In the initial state, the consumer 53 is disconnected, there are no currents in the line wires.

Relay 4 is set to a current value exceeding the permissible load current of an electrical consumer 53. Relay 5 and 6 are tuned to the value of the no-load current of the electrical consumer, and the response current of relay 5 is less than the response current of relay 6,

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Each of the minimum 19-22 current relays has a tripping current corresponding to a specific power consumption class, the tripping current of each subsequent minimum current relay is less than the previous one (Te

When replacing a power consumer, for example, two classes below, relays 19 and 20 are disconnected, because with decreasing power, the current in the network decreases, which becomes less than the release current of relays 19 and 20

 erg J-cp2i Jep20 Jcp) When starting, the contacts 48 are closed, the contacts are connected along the line wires A, B, current flows. At the output of the current sensor I (on the capacitors 33 and 34) voltage appears, sign, C

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measures 15 and 28 of relay 19, resistance shunt 11 and 24, and contacts 16 and 29, resistance shunt 12 and 25.

This example shows the automatic setting of the protection setpoint for five power classes electrically preventing relays 4, 5, and 6. To prevent the -15 bntel, the device has a device actuation at the time of the ability to automatically start the relay 5 and the contact 7 opens the power supply circuit winding maximum relay 4 current. At the same time, contacts 39-42 of relay 5 are closed, the windings of relays 19-22 are energized and their contacts 35-38 respectively close, and contacts 15-18 and 28-31 of the same relay disconnect the protection setting when changing power consumers of any capacity. This is determined by the number of 20 undercurrent relays and current-limiting resistances in the overcurrent relay 4 and undercurrent 6 relays.

With unacceptable overload current

cabins Then the relay 6 is turned on, the circuit 25 through the relay 4 winding exceeds the current

its contact is 50, and contact 9 is opened, disconnecting with a time delay defined by the constant discharge time of capacitor 33 (about 5-10 seconds), the power supply circuit of relay 5, after which the contact 7 is turned on, short circuit of the power supply of the relay coil 4 .

In stationary mode, the load current is normal. The magnitude of the current, set by the current limiting resistance 10 of the relay 4, is less than its current, so the relay 4 is turned off. The current value set by the current limiting resistor 23 of the relay 6 is equal to the current for its activation and the relay 6 is turned on. Relay 5 is disconnected by pin 9, relay 6, relay 19-20 are turned on.

The automatic setting of the protection set point is as follows.

When replacing a power consumer with power, for example, a lower class, in phases A, B, C of the power consumer, the current decreases, and the voltage at the output of current sensor 1 decreases. The current through the relay 19 becomes less than its release current and the relay 19 is turned off. At the same time, contact 35 of relay 19 is opened, contacts 15 and 28 of the same relay are closed, resistance shunt 11 and 24 and at the same time keeping relative (relative to the nominal current of the installation) relative protection settings of relay 4 and 6.

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operation of the relay and it is disconnected by its contact 7 disconnecting the power supply circuit of the relay 6, after which contact 50 of the relay 6 in the circuit of the magnetic circuit 47 is open. Consumer 53 is disconnected from the network.

In the south-south mode, the current through the relay 6 is no longer current than its release and the relay 6 is turned off. In this case, the contact 50 of the relay 6 in the circuit of the magneto-trigger circuit 47 and the electrical consumer 53 is disconnected from the network

The device operates in a similar way with phase breaks, as with unacceptable power supply unbalance and voltage, as well as unacceptable voltage drop in the supply network.

The proposed device provides a power outage in time-delayed emergency situations. The time delay of relay 4 is provided by means of an RC-chain 5Q (capacitor 34 and current limiting resistance included in the winding of these relays).

Thus, the implementation of current-limiting resistances in the circuit of maximum 4 and second minimum 6 current relays in the form (n + 1) of successively connected resistors, wired with disconnecting contacts 15-18, 28-31, was additionally introduced45

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When replacing a power consumer, for example, two classes below, relays 19 and 20 are disconnected, because with decreasing power, the current in the network decreases, which becomes less than the release current of relays 19 and 20

measures 15 and 28 of relay 19, resistance shunt 11 and 24, and contacts 16 and 29, resistance shunt 12 and 25.

This example shows the automatic setting of the protection setpoint for five power classes, the electric adjustment of the protection setpoint when replacing electrical consumers of any capacity. This is determined by the number of minimum current relay and current limiting resistances in the overcurrent relay 4 and undercurrent 6 relays.

With unacceptable overload current

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operation of the relay and it is turned off, by its contact 7 disconnecting the power supply circuit of the relay 6, after which the contact 50 of the relay 6 in the circuit of the magnetopuster 47 is open. The consumer 53 is disconnected from the network.

In the south-south mode, the current through the relay 6 becomes less than its release current and the relay 6 is turned off. In this case, the contact 50 of the relay 6 in the magnetic trigger circuit 47 and the consumer 53 is disconnected from the mains

The device works in a similar way with phase breaks, as with unacceptable asymmetry of the supply currents and voltage, as well as with unacceptable voltage drop in the supply network.

The proposed device provides a power outage in case of time-delayed emergency situations. The time delay of relays 4 and 6 is provided by the RC-chain Q (capacitor 34 and current-limiting resistances included in the winding of these relays).

Thus, the implementation of current-limiting resistances in the maximum 4 and second minimum 6 current relay circuit in the form (n + 1) of series-connected resistors, shunted by disconnecting contacts 15-18, 28-31, was additionally introduced5

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Relays 19-22 of the minimum current provide automatic correction of the settings for the operation of the protection when the power consumption changes. This contributes to the efficiency of the device.

Claims (1)

Invention Formula A device to protect the consumer from damage, containing a current transformer, the primary winding of which has clamps for connecting one of the phases of the electrical consumer to the power supply circuit, a maximum current relay and the first and second minimum current relay, the first winding terminals of which through the break contacts respectively the maximum current relay. the first minimum current relay and the second minimum current relay are connected to the first secondary view of the current transformer and the anode of the first diode; the second terminals of the relay coils are current and, respectively, the first, second and third current-limiting resistances are connected to the cathode of the second diode, the anode of which is connected to the second output of the secondary winding of the current transformer and the cathode of the first diode, the winding of the first and second minimum current relays and after Compiled by V.Onuchin Editor N.Kishtulinets Tehred / .Kravchuk Proofreader L.Natai Order 721 Circulation 473 BNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 4/5, Moscow, Zh-35, Raushsk nab. 113035 0 0 five current-limiting resistances connected to them are first and second capacitors respectively, a chain of series-connected windings of a magnetic starter, a Stop button, a closing contact of the second minimum current relay, and a Start button, shunted by the closing contact of a magnetic starter, has clamps for connecting to two other phases of the power supply network, the power contacts of the magnetic starter have clamps for connection to the phases of the power supply mains network, characterized in that, in order to Improving the efficiency of the device by automatically correcting the protection settings, the current-limiting resistances in the maximum and second minimum current relay circuits are made of (n + 1) series-connected resistors, each of the n resistors is bridged by the opening contact of one of the n additionally introduced minimum relays current, winding through parallel connected contact contact of its relay and additional closing contact of the first minimum current relay n dklyucheny between the first anode and the cathode of the second diode Subscription