SU1325615A1 - Device for protection of disconnection of three-phase network with insulated neutral wire - Google Patents

Abstract

The invention relates to electrical engineering and is intended to protect against leakage of current in a network with an insulated neutral. The purpose of the invention is to increase the shutdown speed when power is applied to a network with damaged insulation. If there is a jjycKOBoro limiter 9 increase, it is the amplitude of the reference current B of the reference source circuit, if its time constant. is greater than or equal to the time constant of the operational source, the operational current TJJP already at a value of the platoon current Igj opens the measuring transistor-. (L

Description

Horo block 7, and with a further increase in current-1

on

which is for all the time

its change exceeds the reference current I ". , the transistor of the block 7 remains in the open state. The output relay of block 7 is not energized, and its contact remains closed. The invention relates to devices for direct disconnection in three-phase electrical networks with an insulated neutral transformer.

The purpose of the invention is to increase the speed of disconnection when power is applied to a network with damaged insulation.

Figure 1 shows the basic electrical circuit of the device; Figures 2 and 3 are time diagrams of the variation of the operational and reference sources of currents when voltage is applied to the network with damaged insulation in the known and proposed devices, respectively.

The device contains a constant operational source 1, a connecting choke transformer 2, a compensating choke 3 and a coupling capacitor D, the first 5 and second 6 resistors, and a transistor measuring unit 7 with an output relay. The input of the transistor unit 7 is shunted by a diode 8 to which a source of a unipolar current impulse current is connected through the starting limiter 9 of increasing amplitude of the reference current, to the power source 11 an intermediate relay circuit 12 consisting of a series of connected resistors, output contact disconnecting The relay of the transistor unit 7. A capacitor is connected in parallel with the contact and the relay 12. The contacts of the intermediate relay 12 (not shown) affect the releases or the disconnecting coil of the circuit breaker 13, which realizes the tripping of the protected three-phase network in the event of insulation failure. 14 The device operates as follows.

The daily pej-ie 12 is triggered without a time delay. The presence of a time delay in the target of the reference source will increase the speed of the device when voltage is applied to the network with damaged insulation for the time t ritp. 3 pcs.

five

ten

15

20

25

thirty

35

40

in the absence of insulation damage 14, the operational current Igp, proportional to the constant voltage of operational source 1, closes the circuit: ground, the resistor 5 of the windings of the throttles 3, the resistor 6, the emitter-base junction of the transistor of the transistor unit 7. In this case, the reference current 1 proportional to the instantaneous values of the unipolar pulses of the reference source 10 flow through the diode 8 and the starting limiter 9. As a result, the difference current between this periodically opens and closes the transistor of the unit 7. In normal operation, the device oystva and no damage to the network through the output unit 7, the relay coil current flows discharging capacitor connected to the transistor unit 7. -etogo current magnitude is sufficient to actuate a relay output relay unit 7 and its holding in the attraction of the armature-mentioned state.

Contact of the specified relay in the circuit of the intermediate relay 12 is opened. Relay 12 is de-energized. The circuit breaker 13 is not blocked. When insulation fault 14 appears, the operational current 1 increases, surpasses the magnitude of the reference current Ig-j. and opens the transistor of the block 7. The output relay de-energizes and by its contact closes the circuit of the intermediate relay 12, which is triggered by means of the automatic switch 13 disconnects the damaged network.

Yri supplying voltage to the network with damaged isolation, the operating current is closed through a resistor 14, a connecting transformer choke 2, compensating choke 3, a resistor 6, and a transistor input of the block

313

7. The increase in operating current is as follows. In the absence of a time delay in the reference current circuit (Fig. 2), the operational current reaches zero from the zero value, the charging current 1. The transistor relay and the differential current between I and periodically opens and closes the transistor of block 7, as a result of which the output relay of block 7 operates and holds its measles is in a drawn state, and its contact remains open.

Then the operating current 1 reaches the threshold value (the result of this. Transistor of unit 7 opens, the output relay releases its measles and its contact closes the intermediate relay 12, which with the help of an automatic switch produces a network disconnection. which is determined by the time of the periodic operation of the transistor of the block 7, until the operating current from reaches the value. In the presence of the starting limiter 9 of the increasing amplitude of the reference current in the reference and If its time constant is greater than or equal to the time constant of the operational source (FIG. 3), the operating current already at the value opens the transistor of the block 7 and with further increase of I, which for all its duration

at

Exchange exceeds reference current I

the transistor of the block 7 remains in the open state.

The output relay of block 7 is not energized and its contact remains in the closed state. Intermediate relay 12 operates without a time delay. The presence of a time delay in the reference source circuit increases the speed of the device when the voltage is applied to the network with damaged insulation 14 for a time. In this case, the presence of a time delay in the circuit.

which source, the time constant of which is greater than or equal to the time constant of the constant operational source with damaged insulation and less than it (Ion Fig.Z curve) with infinitely high insulation resistance 14, does not change the charging time of the output relay of unit 7 when voltage is applied to the network, when insulation is within acceptable limits for safety conditions.

5 Ш 5 20 25 30 35

40 of the claims

A device for protective disconnection in a three-phase network with insulated neutral, containing a connecting choke-transformer, the input terminals of which are used to connect to the phase conductors of the network, and the output are combined and connected via the first resistor to ground, and through the compensating choke to the first - the separation capacitor and the first input of the second resistor, while the second output of the coupling capacitor is connected to the ze, and the second output of the second resistor is connected to the first input of the transistor measurement unit with an output relay and a diode cathode, the anode of which is connected to earth via a source of operational current, a source of uni-polar pulse current, the positive terminal of which is connected to the second input of the transistor measuring unit with an output relay and diode anode, characterized in that In order to increase shutdown speed when voltage is applied to the network with damaged isolation, a starting limiter of increasing amplitude is inserted into it, connected between the negative terminal of the source of a unipolar pulsed eye transistor and the first input of the measuring unit with the output hardly p.

on

Fig.Z

Fi, 2

Editor M, Blanar

Compiled by N. Chutchev

Tehred L. Oliynyk Proofreader S. Shekmar

Order 31 19/51

Circulation 617. Subscription VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d. A / 5

Production and printing company, Uzhgorod, st. Project, 4

Claims (1)

Claim A device for protective shutdown in a three-phase network with isolated neutral, containing a connecting choke-transformer, the input terminals of which are used to connect to the phase wires of the network, and the combined outputs are connected through the first resistor to ground, and through the compensating inductor to the first input of the isolation capacitor and the first input of the second resistor, while the second output of the isolation capacitor is connected to ground, • and the second output of the second resistor is connected to the first input of the transistor a unit with an output relay and a cathode of a diode, the anode of which is also connected to ground through an operating current source, a unipolar pulse current source, the positive terminal of which is connected to the second input of a transistor measuring unit with an output relay and an anode of a diode, characterized in that, in order to increasing the shutdown speed when applying voltage to the network with damaged insulation, a start-up limiter of increasing amplitude is inserted into it, connected between the negative terminal of the unipolar pulse current source and rvym input transistor 'measuring unit with the output relay.