RU177486U1 - ARC-FREE ELECTRONIC-MECHANICAL CONTACTOR - Google Patents

Abstract

The utility model relates to the field of electrical engineering and can be used in DC switching devices. The technical result of the utility model is to increase the reliability of the contactor, expressed in the elimination of arcing on the contacts of the main relay during their bounce when the contactor is turned on by closing them after switching on the load current by a shunt power transistor and reducing the power of the switching transistor and auxiliary relay, a reduction in the load current flow time through them up to tens of milliseconds.

Description

The proposed technical solution relates to the field of electrical engineering and can be used in DC switching devices.

A prior art device is known for arc-free switching of an electrical circuit [RF patent 2557008, H01H 9/30, application. 05/22/2013, publ. 11.27.2014], containing mechanical contacts connected in series with a high-resistance resistor made in the form of a rheostat or a lockable thyristor. When the circuit is switched, the variable resistor is brought to the position (state) with the maximum resistance value (up to 10 ¹⁵ Ohms), at which the switched current becomes insufficient for the formation of a spark discharge. The disadvantage of this technical solution is the energy loss in the resistor in the on position and during circuit switching, the possibility of spark discharge when regulating the resistance of a variable resistor, made in the form of a rheostat, and low speed.

Known arc-free switching devices [RF patent 2298249, HH 9/30, decl. July 14, 2004, publ. 04/27/2007] and [RF patent 2293392, H01H 9/30, claimed. 08/10/2005, publ. 02/10/2007] containing mechanical contacts connected in series with a semiconductor key. In the first device, the key is controlled by contacts using a capacitor, a resistor and two diodes, and in the second, by a microcontroller. Arc-free circuit switching in both devices is achieved by the fact that when the circuit is disconnected, the semiconductor switch is opened first relative to the contacts, and when turned on, the second. The disadvantage of these devices is the large power loss in the transistor key, which requires the use of a powerful transistor with a cooler.

Closest to the claimed technical solution is an arc-free electronic-mechanical contactor [RF patent 2319248, H01H 9/30, decl. 11/23/2006, publ. 03/10/2008], consisting of a main relay, the contacts of which are connected in series with the current sensor, an auxiliary relay, whose contacts are connected in series with the transistor switch, whose electrical circuit shunts the contacts of the main relay and current sensor, and the semiconductor switch and auxiliary relay are controlled by the control device , which ensures that the transistor and auxiliary relay turn on after closing the contacts of the main relay and turn off the transistor, and then the auxiliary relay after opening contacts of the main relay. As a result, the contacts of the auxiliary relay open the de-energized circuit without arcing. The disadvantages of this technical solution are:

- the contacts of the main relay include the inrush current of the load, often several times higher than the nominal, which leads to the appearance of a short (up to 1 mm), but multiple arc with a bounce of contacts, which burns out the contact material;

- part of the load current In (about 1/3 In) flowing through the shunt main contacts of the circuit in the on state of the contactor, since the electrical resistance of the transistor and the auxiliary relay contacts connected in series is comparable (not much more) with the resistance of the main relay and current sensor contacts connected in series ; this requires the use of a sufficiently powerful transistor with a cooler and an auxiliary relay.

The technical result of the utility model is to increase the reliability of the contactor by eliminating arcing on the contacts of the main relay during their bounce when the contactor is turned on and reducing the power of the switching transistor and auxiliary relay.

This technical result is achieved by the fact that the arcless electronic-mechanical contactor, consisting of the main and auxiliary electromechanical relays, a power transistor connected in series with the contacts of the auxiliary relay, whose circuit shunts the contacts of the main relay, and a control device, characterized in that it contains two more transistors each of which is connected in series with the relay coils, and the control device is made in the form of a programmable microcontroller that controls the work of transistors and is programmed so that when the contactor is turned on, the auxiliary relay is turned on first, then, after closing its contacts and their bounce, the power transistor, then the main relay and then, after closing the contacts of the main relay and their bounce, the power transistor turns off, and when it is turned off the contactor first turns on the power transistor, then the main relay turns off, then, after the switched-off current passes into the shunt circuit, the power transistor turns off and then the auxiliary relay.

The specified order of operation of the contactor circuit elements and the duration of their on and off states is ensured by the specified algorithm for the operation of the programmable microcontroller.

The invention is illustrated by drawings, which depict:

In FIG. 1 is a circuit diagram of the inventive arcless electronic-mechanical contactor.

In FIG. 2 - time diagrams of the state of contacts, voltages and currents of the elements of the contactor circuit when turning on, on and off, where the following notation is adopted:

K9 - state of the control key 9;

U _z.5 , U _z.6 , U _z.7 - control voltages at the gates of transistors 5, 6, 7;

K2, K4 - status of contacts 2 of the main relay 1 and contacts 4 of the auxiliary relay 3;

i _vT7 , i _k2 - currents of the power transistor 7 and contacts 2 of the main relay 1.

The arcless electronic-mechanical contactor contains a main relay 1 with contacts 2, an auxiliary relay 3 with contacts 4, transistors 5 and 6 connected in series with the relay coils, a power transistor 7 connected in series with contacts 4, the circuit of which shunts contacts 2, a programmable microcontroller 8 , which controls the operation of transistors, and a control key 9.

The contactor operates as follows. When the control key 9 is closed, the microcontroller 8 turns on the transistors in the following sequence. First, it turns on transistor 6, while the supply voltage is supplied to the auxiliary relay coil 3 and, after the response time t _{cp.3 of} relay 3, its contacts 4 are closed. Then, after a tinkling time t _{other 4} contacts of auxiliary relay 3, it turns on the transistors 5 and 7. The power transistor 7 carries out an arcless load switching, and the transistor 5 supplies a supply voltage to the coil 1 of the main relay. After the response time t _{cp.1 of} relay 1, its contacts 2 are closed and a significant part of the load current (approximately 2/3 I _n in the prototype) flows from the shunt circuit to the main contact circuit. In this case, arcing at the contacts 2 during their bounce does not occur; since the voltage on them is not enough for the formation of an arc discharge. After the bounce of contacts 2, the microcontroller 8 turns off the transistor 7 and the entire load current finally passes to the main contact circuit 2. So the contactor carries out an arc-free load connection.

The supply voltage to the auxiliary relay coil 3 and, after the response time t _{cp.3 of} relay 3, its contacts 4 are closed. Then, after the bounce time t _{other 4} contacts of auxiliary relay 3, it turns on transistors 5 and 7. The power transistor 7 carries out arcless load switching, and transistor 5 supplies power to coil 1 of the main relay. After the response time t _{cp.1 of} relay 1, its contacts 2 are closed and a significant part of the load current (approximately 2/3 In in the prototype) flows from the shunt circuit to the main contact circuit. In this case, arcing at the contacts 2 during their bounce does not occur; since the voltage on them is not enough for the formation of an arc discharge. After the bounce of contacts 2, the microcontroller 8 turns off the transistor 7 and the entire load current finally passes to the main contact circuit 2. So the contactor carries out an arc-free load connection.

When the contactor is on, the entire load current flows only through the contacts of the main relay.

To turn off the contactor, open the control key 9. The microcontroller 8 turns on the transistor 7 and turns off the transistor 5. The load current begins to flow into the main circuit 2 shunting the main contacts. After the return time t _v. 1 of the main relay 1, its contacts 2 open and the load current finally passes to the shunt circuit. In this case, an arc discharge at contacts 2 does not occur, since the voltage on them is insufficient (approximately 1 ÷ 2 V) for the formation of an arc discharge. After the current has completely transferred to the main contacts shunt 2, the microcontroller 8 turns off the transistors 7 and 6. Transistor 7 performs an arc-free disconnection of the load current, and transistor 6 turns off the auxiliary relay 3, contacts 4 of which provide complete galvanic isolation of the load from the mains. Thus, an arc-free load shedding is carried out.

Thus, the use of two additional transistors and a programmable microcontroller with the described operation algorithm allows to exclude arcing on the relay contacts when it is turned on and off, significantly reduce the load current flow time through the main shunt contacts of the circuit, and thereby reduce the required power of the shunt power transistor and auxiliary relay. Thus, the use of two additional transistors and a programmable microcontroller with the described operation algorithm allows to exclude arcing on the relay contacts when it is turned on and off, significantly reduce the load current flow time through the main shunt contacts of the circuit, and thereby reduce the required power of the shunt power transistor and auxiliary relay.

Claims (1)

An arcless electronic-mechanical contactor consisting of a main and auxiliary electromechanical relays, a power transistor connected in series with the contacts of the auxiliary relay, whose circuit shunts the contacts of the main relay, and a control device, characterized in that it contains two transistors, each of which is connected in series with the coils the main and auxiliary relays, and the control device is made in the form of a programmable microcontroller connected to transistors and carrying out when the contactor is turned on, the transistors are turned on in the following sequence: first turns on the transistor, connected in series with the auxiliary relay coil, then with a delay for the time of operation of the auxiliary relay contacts and their bounce, turns on the power transistor, then the transistor connected in series with the main relay coil, then with a delay during the operation of the contacts of the main relay and their bounce, it turns off the power transistor, and when the contactor is turned off, it turns on the power transistor, then off chaet transistor connected in series with the coil main relay, then after a while returning the main switch and the transition current to be interrupted in the shunt circuit, and turns off the power transistor and the transistor is then connected in series with the coil of the auxiliary relay.

Images