SF6 load break switches are designed for switching circuits with currents up to 630 A in 6 kV, 12 kV, and 20 kV / 50 Hz three-phase a.c. networks with isolated or impedance-grounded neutral.
SF6 disconnectors are designed for switching circuits at no load with currents up to 1000 A in 6 kV, 12 kV, and 20 kV / 50 Hz three-phase a.c. networks, as well as for providing safety during maintenance of electrical installations.
| Parameter | Load break
switches | Disconnectors | ||
| Rated voltage, kV | 12, 20 | |||
| Maximum operating voltage, kV | 12, 24 | |||
| Rated current, A | 630 | 1000 | ||
| Rated breaking current, A | 630 | - | ||
| Rated breaking current for unloaded transformers, A | 16 | - | ||
| Rated breaking current for unloaded cables, A | 25 | - | ||
| Short-time withstand current, kA | 51 | |||
| Short-time thermal current (3 s), kA | 20 | |||
| Rated short circuit making capacity, kA | 20 | - | ||
| Mechanical endurance (quantity of cycles ON–tп–ОFF): |
|
| ||
| – line contacts | 2000 | |||
| – grounding contacts | 1000 | |||
| Electrical endurance (quantity of cycles ON–tп–ОFF for switching rated current), at least | 100 | - | ||
| Rated SF6 excess pressure in device enclosure, kgf/cm2 | 0.5 | |||
| Max. SF6 annual leakage from device enclosure, % | 0.2 | |||
| Min. life until discarded, years | 30 | |||
The basic structural elements of the apparatus are as follows: an epoxide-compound casing and a drive.
The casing of the series SL switching apparatus is a sealed epoxide-compound enclosure filled with sulfur hexafluoride (SF6) under 0.5 atm. excessive pressure.
The general view of the series SL load break switch or disconnector:
The general view of the series SL-BT load break switch with fuses and additional earthing switch:
The series SL apparatus operator is made as a separate unit and represents a spring-actuated mechanism that provides rotation of the shaft with the required values of the moving contact rotation angle, speed, and direction of rotation. Depending on its version, the operator is controlled either manually or remotely.
The contact system of the apparatus can take three fixed positions in the following order: On - Off - Earthed
Switching apparatus control sockets, spring-actuated mechanism status indicators, apparatus position indicators, electromagnetic locks, and a high-voltage indicator are located on the front panel.
Apparatus manual closing/opening is performed by means of a free manual operation handle.
The apparatus status indicator is rigidly connected to the moving contact shaft.
The series SL switching devices are furnished with operators that come in three versions:
- manually-operated (type H);
- with spring pre-charge (type T);
- motor-operated (type M);
Depending on the cubicle main circuits, the load break switch/disconnector can be equipped with an additional earthing switch.
A panel with post insulators and an earthing rod serves as a basis for the apparatus additional earthing member or earthing switch, driven either by its own operator (in case of an earthing rod) or the apparatus operator (in case of an additional earthing member). The knife of the additional earthing rod has a lock to prevent a spontaneous opening of the earthing switch. The spring system of the operator provides a stable operation of the earthing knife irrespective of personnel's actions.
Bushing potential devices can be used as post insulators for installation of phase contacts, which together with voltage indicators installed in the operator enables voltage availability control on earthed bays.
Unlike obsolete VNA, VNP, and VNR load break switches or RVZ/RLN disconnectors, the series SL break switches and disconnectors are installed perpendicularly to the busbars, have no adjustable operating rods, and do not need servicing after switching.
- Considerable reduction of the switching apparatus cost thanks to the fact that two functions are implemented in a single apparatus - a load break switch (disconnector) and an earthing switch;
- Implementation of an interlock system to prevent an incorrect operation of the device.
The sealed casing filled with sulfur hexafluoride allows:
- Implementation of a simple yet reliable arch-quenching system;
- Protection of the contact system against environmental exposure: dust and moisture;
- Development of a switching apparatus that is maintenance-free during the whole service life;
- Minimization of occurrence of an open electric arc.
The transverse location of the switching apparatus relative to the busbars allows:
- Implementation of a simple yet reliable operator installed immediately on the shaft and has no additional rods;
- Considerable reduction of dimensions of MV panels;
- Simplification of the switchgear bus system.
You should use a configurator to calculate the cost of series SL load break switches and disconnectors. The configurator simplifies the procedure for selection and ordering of series SL three-position SF6 gas-insulated switching devices to the maximum. Going stepwise through the procedure, the Client can define the configuration and makeup of the apparatus.
The registered users can see immediately the price for the generated request. For JSC «PO Eltechnika» partners, the price displayed includes the discount offered. After the apparatus is defined (configured), the generated request can be either immediately sent to JSC «PO Eltechnika» experts or saved and printed out for the subsequent signing.