The VF12 vacuum circuit breakers are designed for operation as a part of cubicles and switchgears in three-phase MV networks having insulated or impedance-grounded neutral with rated voltage of 6(12) kV, frequency of 50 Hz, and rated current up to 3150 A.
| Parameter | Value |
| Rated voltage, kV | 12 |
| Maximum operating voltage, kV | 12 |
| Rated current, A | 630; 800; 1000; 1250; 1600; 2000; 2500; 3150 |
| Rated breaking current, kA | 20; 25; 31,5 |
| Through short-circuit current rated parameters: | |
| Short-time withstand current, kA | 51; 63; 81 |
| - Short-time thermal current, kA | 20; 25; 31,5 |
| - Short-circuit current flow time, s | 3 |
| Rated power supply voltage for control circuits and auxiliary circuit components, V | ~110; ~220;
=110; =220 |
| Rated voltage for heating circuits, V | ~220 |
| Rated voltage for motorized trolley control circuits, V | =220 |
| Rated current for control circuits, A, max. | |
| - Closing / opening solenoid | 1 |
| - Overcurrent releases | 5 |
| Operating voltage range for control circuits (a.c. / d.c.), % of Irated: | |
| - Closing solenoid | 70-115 / 85-105 |
| - Opening solenoid | 65-120 / 70-110 |
| - Spring-loading motor | 85-110 |
| Main circuit insulation test voltages, kV: | |
| – One-minute, 50Hz | 42 |
| – Lighting impulse, 1.2/50mks | 75 |
| Opening time, s, max. | 0,035 |
| Closing time, s, max. | 0,055 |
| Contact closing/opening time delay, s, max. | 0,002 |
| Mechanical endurance (number of On-tn-Off cycles), min.: | |
| – For 630A; 800A; 1,000A; 1,250A; 1,600A switches | 30000 |
| – For 2,000A; 2,500A; 3,150A switches | 10000 |
| Electrical endurance (quantity of cycles ON–tп–ОFF at rated current), min.: | |
| – For 630A; 800A; 1,000A; 1,250A; 1,600A switches | 30000 |
| – For 2,000A; 2,500A; 3,150A switches | 10000 |
| Electrical endurance (quantity of cycles ON–tп–ОFF at short-time withstand current), min.: | 50 |
| Min. life until discarded, years | 30 |
Structurally, the VF12 vacuum circuit-breaker represents a metal casing on which three poles of the main current-carrying circuit are installed. The casing is made of structural steel plate and coated with a powder paint.
A spring-motor operator is housed in the casing the controls of which are installed on the switch front panel.
The main component of each pole represents a vacuum arc-quenching chamber installed inside the pole. The pole casing represents a multi-layer structure of silicone and epoxide compounds serving insulating and protecting functions.
The drawout version of VF12 vacuum circuit-breakers is complete with a motorized trolley and a contact system.
The base of the VF12 vacuum circuit breaker represents a vacuum arc-quenching chamber.
The special geometry of the arc-quenching chamber contacts generates an axial magnetic field inside the whole area where the arc column is located. Thanks to that phenomenon, a compressed arc takes the shape of a diffused arc evenly distributed over the contact surface at any value of the cutoff current. So, heat load on the contact is reduced thereby reducing their local overheating and the subsequent erosion. As a result, an even wear of contacts and improvement of the vacuum arc-quenching chamber service life is ensured.
The pole casing represents a cast structure of insulating materials. The arc-quenching chamber is installed inside the pole. The pole terminal leads are connected to the respective contacts of the arc-quenching chamber.
The multi-layer design of the pole casing made of silicone and epoxide compounds provides high insulating properties and robustness of the pole. The first silicone compound layer is applied immediately onto the arc-quenching chamber and provides high strength of the arc-quenching chamber insulation. The second epoxide compound layer also provides high mechanical endurance in addition to the insulation strength.
The arc-quenching chamber moving contact is linked to the circuit breaker operator common shaft mechanically.
The casing serves the carrying and protective function for operator components. In the section of the casing where the operator is located the inner space is divided into compartments by metal partitions, which enhances the reliability of the operator and the safety of works during the scheduled maintenance.
A spring-driven operator is used in the circuit breaker, using the mechanical energy of a pre-loaded spring. The spring-actuated mechanism provides moving of the moving contact rods of the arc-quenching chamber with the required speed and movement characteristics.
The spring pre-charge can be performed in two ways:
- automatically with the help of a gear motor (operating mode);
- manually, with the help of a handle.
Operating is performed either by means of push-buttons located on the front panel or by control solenoids.
The operator controls and indicators are located on the front panel. The spring pre-charge indicator displays its current status: charged/ not charged.
- Versatile design allows both fixed mounting of the circuit breakers and mounting on draw-out trolleys in cubicles and switchgears.
- The power leads are located on the front side of the circuit breakers. The draw-out mechanism is designed for the middle position of the trolley. Easy drawing in/out of the trolley ensures skew- and shock-free engaging/disengaging of the tulip contacts.
- The undismountable design of the VF-12 pole improves the electrical endurance, reliability of the insulation and protects the chamber against against adverse environmental exposure.
- The vacuum chamber design employs the AMF technology providing uniform arc distribution across the surface of the contacts excluding their premature wear and erosion.
- The design of the operator with spring-charge motor does not require the use of power supplies or control units and can be operated manually. The circuit-breaker operator features a high mechanical reliability and a low power consumption.
- The operator of the VF12 circuit breaker features short acceleration and deceleration times. Efficient damping provided by the operator excludes undesirable contact chattering during closure thereof.
- In closed position the contacts are spring-loaded to minimize the contact resistance. In this case the heat dissipation in the arc chutes during continuous flow of current is reduced.
- The possibility of installation of mechanical interlocks to lock other devices of the switchgear from the fixed version of VF12.
- The possibility of installation of 5A overcurrent releases for use in deshunting circuits.
- Minimum lead time and competitive price.
For information on the price of the desirable configuration and for ordering VF12 vacuum circuit-breakers (including options) please send the filled-out data sheet at the general address info@elteh.ru