SU655346A3 - Device for protective disconnection in ac circuit - Google Patents

Description

(54) DEVICE FOR SAFETY SHUTDOWN IN AC POWER NETWORK

zero sequence current format

The drawing shows an electrical diagram of the proposed device.

The circuit includes the protected network 1, the main switch 2, the primary winding 3 of the current transformer zero-sequence intermediate transformer 4, the executive relay 5, button b "Stop, button 7" Start, single-phase load 8, three-phase load 9, electrical installation housing 10, current-limiting Reznstor 11, button 12 "Monitoring of health, the secondary winding 13 of the zero-sequence current transformer, the starting block 14 and the button 15 on.

The main switch 2 is connected to the poles of the network 1, consisting of phases and zero thickness. The contacts of the main switch 2 are connected to the poles of the primary winding 3 of the zero-sequence current transformer and with zero thickness. The primary windings 3 are connected in series with the phases and the zero bus. The secondary winding 13 is connected to the starting unit 14, turned on with the help of the button 15 of the main switch 2, and serves to control it. The other poles of the primary winding 3 are connected via working contacts a, b with the executive relay 5 in series with the zero-phase loads 8 or three-phase loads 9. The other end of the zero-voltage primary winding 3 is connected directly to the single-phase load 8 or to the three-phase load 9. Other ends of the primary windings 3 are connected between the poles of a zero-winding winding and one of the phases and the poles of the primary winding of a transformer 4 (220-24 V). One pole of the secondary winding of the transformer 4 is connected to the zero point of the contact of the zero main switch 2, and the other zero is connected in series with the button 6 "Ston and through the locking contact d of relay 5 to the zero point of the winding relay 5, and in series with the button" Start 7 to the current pole of the relay coil 5. The other zero of the executive relay 5 is connected via a series-connected button 12 and a current limiting resistor 11 to the other pole of the primary phase winding, as well as the case 10 of a single-phase 8 and three-phase 9 loads.

The other pole of the housing 10, in turn, is connected to the contact of the zero main switch 2.

Works the proposed device as follows.

The network current flows through the working contacts of the main switch 2 and the primary winding 3. The flowing current through the working contacts of the relay 5 flows to the poles of a single-phase load 8 and a three-phase load 9. The latter can turn on symmetrically and asymmetrically. After power on

main switch 2, the network current flows through the primary windings 3 of the zero-sequence current transformer, intermediate transformer 4 and the working contacts a, b, from relay 5 to zero of loads 8 and 9, if the button 7 is pressed the secondary winding of the intermediate transformer 4 (24 V ) through the contact separating button 6 "Groan, winding

relay 5, housing 10 connected to contacts 2. Executive relay 5 is in an attenuated state, but the current of the secondary winding of the transformer 4 does not stop. Relay 5 contacts provide self-locking.

In case of a closure to the body of the protected device, the emergency current flows from the housing 10 through the pole of the zero switch of the main switch 2. This current creates induction in the secondary winding 13 of the current transformer, which through the starting block 14 of the main switch 2 disconnects the loads 8 and 9 from the mains.

In case of damage or disconnection of the connection of the housing 10 to the contacts of the main switch and one of the phases after the zero sequence current transformer, the secondary circuit of the transformer 4 is broken. As a result, when the main switch is turned on, the winding of relay 5 does not receive 24 V supply voltage, and the relay 5 turns off loads 8 and 9 from the network.

If when the main switch 2 is turned on, a faulty installation is turned on, then the housing short-circuits and as a manifestation of the emergency current, the secondary winding 13 of the zero-sequence current transformer is excited. The start-up unit 14, which enables the main switch 2, prevents the installation in the network, which is in the state of closure to the housing, is switched on in the network.

The operability and reliability of the touch protection circuit can be verified by clicking on the button. It induces, using an emergency current determined by the current limiting resistor I, in the secondary winding 13 of the zero-sequence current transformer as an effect of the emergency current on the electrical installation body 10 and disconnects the loads 8

and 9 by triggering the starting unit 14. main switch 2 from the network. At the same time, he controls the connection between the transformer 4 and the housing 10 of the electrical installation.

The 24 V voltage of the transformer 4 does not violate the standards of protection against contact.

Thus, the proposed device differs from the known ones by ensuring the control of the grounding value, thereby increasing the reliability of human protection.

Claims (1)

Invention Formula A device for protective disconnection in the AC network containing a zero-sequence current transformer, an intermediate transformer. The primary winding of which is connected between one of the mains phases and the neutral wire connected to the housing of the protected electrical installation, an executive relay whose closing contact is bridged by the start button , a circuit breaker and a serially connected button "Health monitoring and a resistor connected between one of the phases and the neutral wire, differing It means that, in order to increase the reliability of work, it is equipped with the Stop button and additional closing contacts of the specified executive relay, included in the network phases between the zero-sequence current transformer and the protected electrical installation, and the executive relay winding is connected between the protected electrical installation case and the closing button A start connected to one end of the secondary winding of an intermediate transformer via the disconnect button “Ston, while the other end the secondary winding of the intermediate transformer is connected to the fixed end of the closing contact of the circuit breaker, to the winding of which the zero-sequence current transformer is connected. Information sources taken into account during exertization 1. Motusko F. Ya. Protective devices in electrical installations. M., "Energia, 1973, with. 184, fig. 5-On.