SU951443A1 - Arcless contact switching-off device - Google Patents

Description

one

The invention relates to electrical equipment, namely, to arcless switching devices of alternating current.

There are known arc-free contact devices containing power contacts and a synchronizing node shunting them, consisting of coils connected in series, an electrically conductive elastic plate, synchronizing and auxiliary contacts, the synchronizing and auxiliary contacts closing at the moment of issuing the trip command and opening synchronously, i.e. before zero current 1.

These devices have low reliability and insufficient accuracy of synchronization of the p-azmykan sync and auxiliary contacts, since the stability of the sync node depends on the size of the switched current.

Devices are also known that contain a main contact discontinuity, which is triggered by two auxiliary contact discontinuities with counter-activated valves. The inclusion of all three parallel pairs of contacts and keeping them in the closed position is carried out by an electromagnetic drive. The arc-less disconnection of parallel auxiliary branches is carried out by alternately de-energizing two more electromagnets into the current pause,

5 generated by the vents 2.

Such devices allow an almost arc-free shutdown, but they are not fast-acting. Their shutdown time reaches 20 ms.

, Q In addition, to transfer the main circuit current to the bypass branch containing the power valve, an arc inevitably arises between the opening contacts of the main break, the voltage drop on which should exceed the voltage

15 sufficient to cover the power valve.

A device containing a synchronization unit in a switched circuit, the main normally closed contact is known.

20, in parallel to which a chain of a normally closed auxiliary contact discontinuity and a current-limiting active resistance is connected, the contacts of the main discontinuity are disconnected from the synchronization unit pulse, and the contacts of the auxiliary discontinuity are automatically disconnected after a current-limiting resistance is introduced into the switchable circuit. Synchronizing the opening process of the main break allows one to reduce the voltage drop on the current-limiting resistance even with large inductances of circuit 3. However, to facilitate arc quenching at the main break, the active resistance value should be taken as small as possible (the arc of the main break does not occur with a short-circuited shunt jumper ). At the same time, the higher the value of the current limiting resistance, the easier the arc suppression occurs in the auxiliary gap. In high current circuits (units of kiloamperes and higher), if the resistance is chosen relatively large, then an arc is burning at the contacts of the main discontinuity. The voltage across the arc must exceed the voltage drop across the resistance so that the current can flow into the shunt circuit with an auxiliary break. If the resistance is small, then the arc will burn longer on the contacts of the auxiliary gap. The closest to the invention in its technical essence is a device comprising a main and auxiliary contact discontinuities with its drives, a synchronization unit including an active and inductive shunt, two variable resistors and a zero-organ, the main, auxiliary contact discontinuities and an inductive shunt, connected in series, the active shunt is connected in parallel to the auxiliary contact discontinuity, variable resistors are connected in parallel to the active and inductive shunts, moving pins are not belt resistors are connected to the inputs of the zero-organ, the output of the zero-organ is connected to the drive of the main contact gaps 4. A disadvantage of the known device is that in the normal state part of the main current flows through the low-resistance active shunt. In addition, in high-current circuits, the main switch has large dimensions and a massive contact system. Due to the inertia of the contact system, the accuracy of the synchronized shutdown is low, which reduces the reliability of the device. The aim of the invention is to improve the reliability of the device. This goal is achieved by the fact that, in an arc-free contact disconnecting device containing a main and auxiliary contact discontinuities with its drives, a synchronization unit that includes active and inductive shunts, in parallel with which variable resistors are connected, a null-organ whose inputs are connected to moving the terminals of variable resistors, with the inductive shunt connected in series with the main contact gap, the auxiliary contact disconnect and the active shunt are connected in series and connected s are parallel to the main contact discontinuity, and the output of the null organ is connected to the actuator of the auxiliary contacts. The drawing shows an arc-free contact disconnecting device. The device contains the main normally closed contact discontinuity, consisting of fixed 1 and movable 2 contacts and an auxiliary normally open contact discontinuity, consisting of fixed 3 and movable 4 contacts. In series with the fixed contact 3 of the auxiliary break, a resistor 5 is turned on, which is the active shunt of the synchronization unit. Inductance 6, standing in a switched circuit, is an inductive shunt of a synchronization unit. Potentiometers 7 and 8 are also connected to the synchronizing unit by means of their leads connected to an electronic null organ 9. The moving contact 2 of the main discontinuity has an electromagnetic shock 10, the coil of which is connected to the primary winding of the power transformer 12 through a two-pole control button 11. the turn may be powered by a commotion. The opening of the contacts 1 and 2 of the main discontinuity during de-energizing the coil of the electromagnet 10 is carried out under the action of the spring 13 and the force of gravity of its core. The moving contact 4 of the auxiliary break has a pulsed drive of the induction-dynamic type in the form of two coils, a turn-on and turn-off coil 14 and a disk 16 rigidly connected with the contact 4. The coils 14 and 15 are powered respectively from capacitive drives 7 and 18, pre-charged from transformer 12 via rectifiers 19 and 20. The discharge of capacitive storage 17 to the turn-on coil 14 is accomplished by shorting a pair of contacts of the two-pole control button 11. The discharge of capacitive storage 18 to the turn-off coil 15 uschestvl an opening thyristor 21 by the clock signal with the zero-body 9 entering the control circuit of this thyristor. The device works as follows. In the normal state, contacts 1 and 2 of the main discontinuity are closed, and contacts 3 and 4 of the auxiliary discontinuity are open. The current path is from terminal a through closed contacts 2 and 1 to terminal b. When a shutdown command is issued, the bipolar control button 11 is turned on. Wherein

Splicing a pair of contacts of the button 11 de-energizes the coil of the electromagnetic actuator 10. The movable contact 2 of the main discontinuity. At the same time, the locking pair of contacts of the button 11 closes the capacitive drive 17 to the coil 14 of turning on the drive of the moving contact 4 of the auxiliary discontinuity. Under the action of electromagnetic repulsive forces between the coil 14 and the short-circuited disk 16, the movable contact 4 of the auxiliary rupture moves to the closure with the fixed contact 3. The movable contact 2 of the main discontinuity under the force of gravity of the electromagnet 10 and the spring 13 moves to the open with the fixed contact 1. Since induction-dyne.michesky drive has a very high speed, the closure of contacts 3 and 4 occurs before the contacts 2 and 1 are open. Then, under the action of the voltage drop On the arc that occurs at the opening of contacts 1 and 2, which has a vanishingly short lifetime, the current from the branch of the main discontinuity flows into a parallel branch of the auxiliary discontinuity. The vanishingly short time of existence of the arc at the contacts of the main discontinuity is provided by a small value of the resistance of the resistors 5 in the branch with an auxiliary discontinuity. The resistor 5 in the proposed device does not perform the function of current limiting and is chosen small enough only to generate a block of synchronization of a signal proportional to the switched current. From inductive shunt 6, a signal is taken that is proportional to the rate of change of the switched current. Both of these signals are multiplied by some coefficients with the help of potentiometers 7 and 8, and when the sum of these signals is equal to zero, the null organ produces a synchronizing pulse that triggers the thyristor 21. Yre.predict the zero of the current to be turned off 8. Thus, the thyristor 21 is opened and the capacitance of the accumulator 18 is sharply discharged onto the turn-off coil 15. Contacts 3 and 4 at the same time open at high speed directly in front of the zero current to be switched off, i.e. with practically no arc ignition.

The movable contact 4 in the open position is locked with a latch.

In the proposed device, the known synchronization scheme of N. M. Chernysheva is used.

The resistance in the switched circuit is overcome by briefly activating the active shunt in the switched circuit, namely for the time from the moment of issuing the shutdown command to the moment the circuit is completely disconnected by the auxiliary contact break. This reduces to a minimum.

energy losses for heating the active shunt, which is especially important in high current circuits. In contrast to the known ones, the proposed disconnecting device allows the implementation of a practically non-arcing co-mutation of high-current electrical circuits, since it uses a small resistance in the branch with an auxiliary break. The application of the known synchronization scheme allows to obtain small values of the lead time of the current, which, in combination with the high-speed auxiliary break drive, provides a high synchronized shutdown efficiency, since the arc burning time at the auxiliary break contacts is significantly reduced. A high-speed device with face contacts, for example, a high-speed air circuit breaker, can be used as a contact breaker.

Bezgugovy switching allows you to increase the breaking capacity of the contact systems of the main and auxiliary gaps, bringing their switching durability to mechanical, as well as their reliability and safety of operation.

The use of an electromagnetic actuator provides the desired sequence of switching when using a single bipolar button up.

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Claims (4)

1. USSR author's certificate number 324659, cl. H 01 H 9/30, 1970. 2. Authors certificate of the USSR Co. 197713, cl. NGAS 9/30, 1964. 3. Butkevich GV. Arc processes in the commutation of electric circuits “Energie, 1973, p. eleven. 4. USSR author's certificate jYo773770, cl. H 01 H 33/60, 1979.