Types of load breakers for 6 — 10 kV

A load break switch is the simplest high voltage switch. It is used to switch off and activate circuits under load.

Switch arc extinguishing devices are designed to extinguish a low power arc that occurs when the load current is turned off. They cannot be used to interrupt short-circuit currents. To break the circuit in the event of a short circuit, high voltage fuses of the appropriate capacity are installed in series with the load break.

Load break switches have replaced expensive high voltage switches. Not only is the high voltage switch expensive, but so is the drive to it. If the supply current is relatively small, 400 — 600 A, it is advisable to replace the relay protection switch with a fused load switch.

Autogas chambers, autopneumatic, electromagnetic, SF6 gas blown and vacuum elements are used in arc extinguishing load breakers.

When autogas is blown, the arc is extinguished by the arcs released from the walls of the gas chamber under the influence of temperature. Automatic pneumatic fan circuit breaker is a small air circuit breaker. To extinguish the arc in such switches, compressed air is generated by the energy of the opening spring. Its operating principle is similar to the blowing principle of an electromagnetic switch.

Automatic switch for gas filling

When used in gas-insulated switch-disconnectors, the arc chute is filled with gas at a pressure of two atmospheres. During the shutdown, the arc is washed away by the gas flow created by the piston device. The movement of the movable contact of the piston device is carried out by the energy of the opening spring. Gas-insulated circuit breakers for voltages up to 35 - 110 kV are commercially produced.

Until now, mainly self-inflating load breakers, such as VN-16 type load breaker switches, have been used.

Load break switch VNP-M1-10 / 630-20

Load break switches are available with grounding blades. Their type is VNPZ-16 (17). Grounding knives are equipped with a shaft, welded contacts in the form of copper plates and a locking device. Blades can only ground the top or bottom contact posts of the circuit breaker, so they are mounted on top or bottom of the circuit breaker. The shaft of the earthing blades is connected to the shaft of the circuit breaker by means of an interlock.

The interlock prevents the grounding blades from closing when the switch is on and the switch from closing when the grounding blades are on.Ground blades can only be switched on and off when the switch is off.

A separate drive type PR-2 is used to control the ground blades. Manual drive can be used. The blade drive is mounted on the side opposite the breaker drive.

Load break switch VNPZ-16

Switch-disconnectors with autogas blowing at 10 kV voltage can break currents of 200 A 75 times, and in the case of 400 A - only 3 times. The low reliability of circuit breakers, small number of rated breaking currents, limited performance and electrodynamic resistance require the development of new types of load breakers. One of them is an electromagnetic type load switch. It is used at nominal currents of 630, 400 A and corresponding nominal voltage of 6, 10 kV.

Such switches have increased breaking currents 1.5 times higher than nominal, and the limiting through currents are the peak value of 51 kA, the effective value of the periodic component is 20 kA. The breaker is equipped with a spring-operated manual winding and remote control.

Vacuum load breakers, small in size and weight, with high operational capabilities, are successfully used as load break switches. Thus, the circuit breaker of the VNVR-10/630 series is designed for a voltage of 10 kV and a rated current of 630 A.

Vacuum load switch VNVR-10 / 630-20

Vacuum Load Switch VBSN-10-20

SF6 load-break circuit breakers are used for voltages of 110 kV and above.For a voltage of 110 — 220 kV, they have fire extinguishing chambers in which the arc is driven in rotation by the field of permanent magnets.

Load Break Switch Actuators

PR-17 actuators are mainly used for manual control of circuit breakers. When remote shutdown is required, the PRA-17 actuator is used, in the case of remote on-off control, the PE-11S electromagnetic actuator. The most common is the PRA-12 load break switch actuation.