MV Switchgears

Vertical switch disconnector (VFD)

The VFD - vertical switch disconnector is designed for switching electrical power supply circuits (switching on/off the load, protection against short circuits and overloads) in AC networks up to 690 V with a frequency of 40-60 Hz at currents up to 630 A. It is produced for currents up to 160 A with a width of 50 mm, and up to 250 A, 400 A, 630 A with a width of 100 mm. Switching operations of the VFD are performed with single-phase or three-phase disconnection. In the disconnected position, VFDs provide a double visible break, ensuring safety in maintenance.

VFDs can be used as:

  • protection devices in low-voltage distribution cabinets of transformer substations;

  • protection devices for incoming or outgoing cable lines;

  • load break switch, main switch disconnector.

Technical specifications:


Model

VFD-160

VFD-250

VFD-400

VFD-630

Rated voltage, Un, V

690

Rated operational voltage, Ue, V by utilization categories

АС-21В

690

690

690

690

АС-22В

690

500

500

500

АС-23В

400

-

-

-

Rated current, In, A

160

250

400

630

Fuse size

00(IEC60269-2)

1

2

3

Frequency, Hz

50-60

Rated insulation voltage, Ui, V

1000

Rated impulse withstand voltage, kV

8

12

Rated 1-minute power-frequency withstand voltage, kV

3

Degree of protection

IP20

Mechanical endurance, cycles

2000

Electrical endurance, cycles

200

Cable cross-section, mm2

10-70

120

240

300

Cable connection method

Bolted, V-shaped terminal

Installation method

On bolts

Utilization category

AC23-B, AC22-B, AC21-B

Rated short-circuit current, kA

120

Rated short-time withstand current

16 kA/s

Mounting

М8

М10/М12

Operating temperature

From -40°C to +50°C

Design and operating principle
VFD: a vertical switch disconnector in which the fuse holder with the fuse link forms a moving contact. VFDs completely replace a structure consisting of a conventional switch disconnector, cables, and fuse holders. The VFD design provides the necessary switching capacity, high mechanical and electrical life, small overall dimensions, low cost compared to a three-phase circuit breaker, and safe operation for maintenance personnel.

The VFD consists of the following parts:

  • a three-pole strip base (installed directly on the live busbars), equipped with spring contact jaws for fuses, connected to cable terminals. Using different types of terminals, it is allowed to use a cable with or without a cable end;

  • a protective housing equipped with arc chutes;

  • a protective cover for the lower contacts;

  • removable block-covers for fuses, providing single-phase or three-phase load disconnection.

Disconnection is performed by pulling the block-cover (lever) towards oneself at an angle of 60 degrees. Disconnection of the VFD can be performed either phase-by-phase or three-phase.

To increase the breaking capacity, the VFD is equipped with arc chutes, which makes it possible to switch off under load.

The quality of the VFD is determined by the contact connection of the blade and the contact posts. The VFD contact system is made using silver alloys, which improves the quality of the contact connection. To improve the connection quality, a line contact is used, which has a lower contact resistance. Contact pressure is provided by steel springs made in the form of a cut ring, the ends of which act on elastic jaws. It is allowed to be equipped with PPN type fuse links.