SU1675995A2 - Device for protective disconnection of electrical installation from alternating current circuit - Google Patents

Abstract

This invention relates to electric shock protection devices. The purpose of the invention is to increase reliability and enhance functionality by providing protection against phase-to-phase faults and short-circuits in electrical installations. When a short-circuit between the phase conductors triggers, the first two current relays open their contacts in the circuit of the first two capacitors, which leads to a violation of the symmetry of the currents in the primary windings of the transformer and the trigger of the magnetic starter. The power is also disconnected if there is damage in the electrical installation itself due to the operation of the second current relays and the opening of their contacts in the third capacitor circuit. Writing the time delay unit 8, the voltage relay and the proximity switches allows the power contacts of the magnetic starter to be switched in de-energized circuits, which increases the reliability of the safety shutdown device. 1 il.

Description

- The invention relates to electric shock protection devices and is intended for means of floor transport (vehicles) with electric power supply via a flexible cable and is an improvement of the invention according to the author. St. No. 694929.

The aim of the invention is to increase the Reliability of operation and the expansion of functional capabilities by providing protection against phase-to-phase faults in electrical circuits.

The drawing shows a schematic diagram of the device.

The vehicle1 receives energy from a transformer substation at

supply four-wire network 1 with a zero wire, which is grounded, and phase wires. The alternating voltage of the power supply network 1 through the protective switch 2 through the four-wire flexible cable 3 is supplied to the electrical installation (vehicle) 4. Electric power is supplied to the vehicle through three phase conductors of the network 1 and cable 3, ensuring its movement and other operations, for example lifting a load. The fourth neutral wire of the cable 3 is connected to the body of the vehicle 4, is grounded, the body and thus provides protection against electric shock to people serving the vehicle.

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The device also includes non-contact alternating voltage switches 5, asymmetric unit 6, diode bridge 7, time delay unit 8 when a voltage relay trips with winding 9 and contacts 10, current relays with windings 11-14 and contacts 15-18 and balances block 19.

The safety switch 2 consists of a start button 20, a stop 21 button 1 of a magnetic actuator 22. containing power 23 and blocking 24 contacts and a winding 25, a zero-sequence current transformer 26, a voltage amplifier 27, a relay 28 with a winding 29 and contacts 30.

Between the power contacts 23 of the magnetic starter 22 and the consumer, which is the vehicle 4, the non-contact alternating voltage switches 5 are connected in series to the phase conductors. Each such switch has two thyristors 31 and 32, two diodes 33 and 34, a resistor 35 and the contacts 10 of the voltage relay, which are connected in series to the circuit formed by the diodes 33 and 34 and the resistor 35.

An asymmetric unit 6 is connected to the connection points of one end of the flexible cable 3 with a neutral wire and with two phase conductors. It has capacitors 36 and 37. The contacts 15 and 16 of the current relays are connected to the circuit of the capacitor 36, the windings 11 and 12 of which are connected in series in two phase conductors.

Parallel to the winding 25 of the magnetic starter 22, a diode bridge 7 is connected by its input. Bridge 7 is connected to a time delay unit 8, which has a capacitor 38, a diode 39, and resistors 40 and 41. The output of time delay unit 8 is connected to a winding 9 of an additional voltage relay . The contacts 10 of the relays are connected to the corresponding circuits of the contactless switches 5 of the alternating voltage.

The electrical equipment of the vehicle 4 is connected to the second end of the flexible cable 3. Its neutral wire is connected to the vehicle body 4. The phase wires of the flexible cable 3 are connected to the primary winding of the transformer 42. The secondary winding of this transformer is connected through the windings 13 and 14 of the current relay with a three-phase diode bridge 43, which feeds straightened-out executive motors (not shown) of the vehicle 4, which provide movement, load lifting

and performing other technological operations.

Installed on the vehicle 4 balun unit 19 is connected

to its case and to that phase wire with which the asymmetric unit 6 does not have an electrical connection. The balancing unit 19 has a capacitor 44 and the Stop button 45. The circuit formed

0. The capacitor 44 and the button 45 include the contacts 17 and 18 of the current relays, the windings 13 and 14 of which are included in the circuits connecting the transformer 42 and the diode bridge 43. The capacitors 36, 37 and 44 have the same capacity, respectively, the same resistance to alternating current and when connected to three different phase wires provide the flow through the primary windings of the transformer 26

0 symmetrical currents (currents whose geometric sum is zero). In this case, with a symmetrical load on the supply network 1 created by the vehicle 4, the voltage on the secondary winding

5 of the current transformer 26 is zero, respectively, the voltage is absent on the winding 29 of the relay 28 and its contacts 30 are closed.

The operation of the device is characterized by the following modes.

In the presence of voltage in the supply network 1, the alternating voltage is supplied only to the amplifier 27 of the protective switch 2, the power contacts 23 of the magnetic putiller 22 are open, and the alternating voltage to the electrical equipment of the vehicle 4 is not supplied.

To quickly supply voltage to the vehicle 4, it is necessary to briefly press the Start button. After pressing this button, its contacts are closed and the alternating voltage is supplied through the closed contacts of the Stop 1 button and the closed contacts 30 of the relay 28 to the winding

5 25 magnetic actuator 22, the latter closes its power 23 and interlocking 24 contacts. The locking contacts 24 create a circuit that ensures the on position of the magnetic actuator 22 after

0 when the start button is released and its contacts open.

For some time after the closing of the power contacts of the magnetic actuator 23 22 contactless switches

5-5 of the alternating voltage is in the off state, therefore, with respect to the moment of turning on the magnetic actuator 22, the electrical equipment of the vehicle 4 is supplied with a certain delay.

Simultaneously with the voltage applied to the winding 25 of the magnetic starter 22, the alternating voltage goes to the input of the diode bridge 7. The rectified voltage at its output is applied to the time delay unit 8 and charges the capacitor 38 through the diode 39 and resistor 40. charging capacitor 38 increases its voltage and the voltage across the winding 9 of the voltage relay. Thus, a turn-on delay of the voltage relay is created relative to the moment the magnetic starter 22 is turned on. The greater the capacitance of the capacitor 38, the resistance of the resistor 40 and the winding 9, the greater the duration of this time delay.

After a time equal to the delay time, the voltage of the winding 9 reaches the setpoint of the voltage relay, the relay operates and closes the contacts 10 in the circuits of the non-contact switches 5 of the alternating voltage. Thereafter, at the beginning of each half-cycle of the alternating voltage, a current appears in the control electrode circuit of the corresponding thyristor, and the thyristor is turned on. At one polarity of an alternating voltage, when, for example, the anode of the upper thyristor 32 is more positive than its cathode, through the upper diode 33, the resistor 35 and the contacts 10 of the voltage relay and the control electrode of this thyristor current flows, this thyristor is turned on and closes the circuit wires

When the polarity of the opposite voltage is opposite, the lower thyristor 31 performs a short circuit. After changing this polarity to the opposite lower thyristor 31, the upper thyristor 32 switches off and on again. Such alternate thyristor switches occur in all non-contact alternating voltage switches 5 with closed pins 10 voltage relays. As a result of this, the circuits of the phase wires are closed, and the electrical equipment of the vehicle 4 is supplied with alternating voltage. Since the proximity switches 5 close the circuits only after the voltage relay trips with contacts 10, which is triggered with some delay in relation to the closing moment of the power contacts 23 of the magnetic actuator 22, the contacts 23 close the circuits with the proximity switches off 5. Therefore, in the absence of current in the circuits switched by these contacts.

The quick release of the voltage from the electrical installation of the vehicle is carried out using the buttons 21 Stop G and 45 Stop 2. The button Stop 2 is mounted directly on the vehicle, therefore it allows you to take off

voltage right from the vehicle

By briefly pressing the button 21 Stop 1, its contacts open, the voltage disappears from the winding 25 of the magnetic starter 22, from the diode bridge 7 and, accordingly, from the winding 9 of the voltage relay. Due to the presence of the diode 39, the time delay unit 8 does not affect the processes in the electromagnetic system.

5 is a voltage relay, and its speed in this mode is determined by the time of failure. Since the voltage relay has a shorter drop time compared to the magnetic starter, for example, if the relay

0 is performed on reed switches that provide for the time of dropping of the tenth fractions of a millisecond, then the voltage relay first drops and opens the contacts 10, then the proximity switches 5 are turned off, and only

5 thereafter, the power contacts 24 are opened (already in the absence of current in the open circuits). Thus, the contactless switches 5 open the operating currents of the vehicle 4 and remove the voltage from its electrical equipment, and the power contacts 23 of the magnetic actuator 22 open the de-energized circuits.

After the 21 Stop 1 button is released and its contacts have closed their circuit,

5, the magnetic starter 22 and the proximity switches 5 do not turn on, since previously the blocking contact 24 of the magnetic starter 22 managed to break the power supply circuits of the winding 25, the diode bridge 7 and, accordingly, the winding 9 of the voltage relay.

After removing the voltage from the input of the diode bridge 7 in block 8 of the time delay, the capacitor 38 is discharged through the resistor 41, and the voltage of this capacitor

5 becomes zero.

By briefly pressing the button 45 Stop 2, the circuit of the capacitor 44 of the balancing unit 19 is disconnected from the floor vehicle body 4 and terminated

0 current in the circuit of this capacitor. In this case, a current continues to flow in the circuits of capacitors 36 and 37 of the asymmetric unit 6. As a result, the symmetry of the currents in the primary windings of the transformer is disturbed.

5 26. In the absence of current symmetry, their geometric sum is disconnected from zero and a voltage appears on the secondary winding of transformer 26, which is increased by amplifier 27. An increased voltage is applied to winding 29 of relay 28. The latter triggers and opens contacts 30.

After opening these contacts, the voltage is removed from the winding 25 of the magnetic starter 22 and from the output of the diode bridge 7. The device then works in the same sequence as after pressing the button 21 Stop 1 and removes the voltage from the vehicle electrical equipment 4.

After removing the voltage from the truck 4, the current in the primary windings of the transformer 26 is stopped, the voltage from the winding 29 of the relay 28 is released, the relay disappears and the contacts 30 close the circuit. At the same time, the magnetic starter 22 and the non-contact alternating voltage switches 5 do not turn on , because by the time the circuit of the contacts 30 is closed, the interlocking contacts 24 of the magnetic actuator 22 have time to open their circuit, and therefore, after the contacts 30 are closed, the alternating voltage does not flow to the magnetic actuator winding 25 , or to the input of the diode bridge 7, Consider the operation of the device.

In case of emergency removal of voltage from the electrical equipment of the vehicle 4 (if the neutral wire is broken, when the person touches the electrical equipment of the vehicle 4, under which there is a short circuit), the device operates as follows.

The breaking of the neutral wire circuit from the point of connection of the asymmetric block to the vehicle body 4 (in cable 3} is accompanied by the cessation of current in the circuit of the capacitor 44 of the balancing unit 19. As a result, in the circuit of the capacitors 36 and 37 of the asymmetric unit 6, the current remains then, there is a violation of the symmetry of the currents in the primary windings of the transformer 26. In the following, the functional elements of the device operate in the sequence that when the button 45 Stop 2 is pressed and provide voltage relief from trooborudovani vehicle 4. Thus, eliminated unacceptable under the conditions of electrical operation of the floor of the vehicle when there is no electrical connection between his body and the ground.

When the person standing on the body

of the vehicle, for the under-voltage parts of the electrical equipment, the latter, the resistance of the person is bypassed by one of the capacitors

36, 37 and 44, depending on which of the phase conductors the person is touching. As a result, the equality of the currents flowing between the phase conductors and

zero wire, and, accordingly, the symmetry of the currents in the primary windings of the transformer 26. The subsequent order of operation of the device does not differ from the previously described order when considering disconnection from the Stop button 2 and the voltage is removed from the vehicle electrical equipment 4 and from the voltage of a person.

If there is a breakdown of the isolation of the phase conductor with respect to the grounded body of the vehicle 4, which is in emergency mode and may be accompanied by potentially dangerous situations, then the symmetry of the current in the primary windings of the transformer 26 is broken, as a short-circuited shunt one of the capacitors 36, 37, and 44. Thereafter, the device operates in the sequence described above, and the voltage is removed from the truck and the pro- No unacceptably high short-circuit current.

When short-circuited between the phase conductors of the flexible cable 3 (such an emergency mode occurs when the cable is broken and is characteristic of the operating conditions), the current relays operate,

windings 11 and 12 of which are connected in series with the phase wires of a flexible cable and white 3, through which emergency short-circuit currents flow. Until current relay trips and contact open

15 and 16, the symmetry of the currents in the primary windings of the transformer 26 is not disturbed. For example, when a short circuit between two phase conductors of a flexible cable 3, an emergency current flows through these wires,

which is of the same magnitude and opposite direction in the primary of the MoiKax transformer 26. In the case of a short circuit between the three wires of the flexible cable 3, the geometric sum

the currents flowing through these wires and, accordingly, along the primary windings of the transformer 25, are always zero.

After the operation of the current relays and the opening of contacts 15 and 16, the current in the circuit of the capacitor 36 of the asymmetric unit 6 stops and the current symmetry is broken in the primary windings of the transformer 26. Next, the device operates in the sequence described above, the voltage is removed from the vehicle 4 and the accident currents stop flowing.

It should be noted that in the event of a short circuit between the middle and right (left) wire, the emergency current flows through the winding 11 (12) of the current relay, its contacts 15 (16) open. When a fault occurs between the three phase conductors, the emergency current flows through the windings 11 and 12 of both current relays, contacts 15 and 16 are opened.

In case of a short circuit in the circuits connected to the secondary windings of the transformer 42 (breakdown of the bridge diodes 43. short circuit on the two poles of the pole, short circuit in the circuits of the transport connection electric motors), the emergency current flows through the windings 13 and 14 of the current relays. As a result, they are triggered, open contacts 17 and 18, after which the current in the circuit of the capacitor 44 of the balancing unit 19 stops, i.e., a mode similar to that occurs when you press the Stop Stop button 45 and open its contacts.

After each of the operational and emergency shutdowns that are described, the device is turned on by briefly pressing the Start button 20. The order of operation of the device after pressing this button is described above.

Thus, the introduction of current relays into a known device and the inclusion of their contacts in asymmetric and balancing units additionally allows using the protective disconnecting device to disconnect the currents of interphase short circuits and short circuits in the load circuit, which expands the functionality of the protective disconnecting device. Since the contacts of the magnetic actuator commutate the circuits without a tick, welding is eliminated, the contact wear is increased, thereby increasing the reliability of their operation.

Formulas of the invention

Device for the protective disconnection of electrical installations in the AC network by aut. No. 694929, characterized in that, in order to increase reliability

operation and expansion of functionality by providing phase-phase protection in electrical circuits, it is additionally equipped with a number of phase conductors with non-contact alternating voltage switches, four current relays, a diode bridge, a voltage relay and a time delay unit, with proximity switches having pins for inclusion in the network

in series with the power contacts of the magnetic actuator from the electrical installation, parallel to the winding of the magnetic actuator, the input of the diode bridge is connected, its output is connected to the input of the unit

time delay, the output of which is connected to the winding of the voltage relay, the closing contacts of this relay are included in the control circuit of the proximity switches, windings of the first and second current

the relays are connected in series with contactless switches, and the windings of the third and fourth current relays have leads for connecting in series to the power supply circuit of an electrical installation after its

input terminals, contacts of the first and second current relays are connected in series to the circuit of one of the capacitors of the asymmetric unit, contacts of the third and fourth current relays are connected in series with the capacitor of the balancing unit.

Claims (1)

Claim Device for protective shutdown of an electrical installation in an alternating current network by ed. St. No. 694929, it is noteworthy that, in order to increase the reliability of operation and expand functionality by providing protection against phase-to-phase faults in the electrical installation circuits, it is additionally equipped with four phase-wise non-contact AC voltage switches by the number of phase wires a relay, a diode bridge, a voltage relay and a time delay unit, the proximity switches having outputs for connection to the network in series with the power contacts of the magnetic starter from the electrical installation side , parallel to the winding of the magnetic starter, the input of the diode bridge is connected, its output is connected to the input of the time delay unit, the output of which is connected to the winding of the voltage relay, the closing contacts of this relay are included in the control circuit of the proximity switches, the windings of the first and second current relays are connected in series with proximity switches, and the windings of the third and fourth current relays have conclusions for connecting in series in the power supply circuit of the installation after its input terminals, the contacts of the first and second a current switch connected in series in the circuit one of the capacitors asimmetriruyuschego block contacts the third and fourth current switch connected in series with the capacitor of the balancing unit.