Switch Fuse Units

SWITCH FUSE UNITS

Switch fuse unit is compact combination, generally metal enclosed of a switch and a fuse. It is very widely used for low and medium voltages. The ratings of switch fuse units are in the range of 30,60,100,200, 400, 600 and 800 amperes. Switch fuse units are available as 3 pole and 4 pole units. They are developed for making capacities upto 46 kA. They can safely break, depending upon ratings, currents of the order of 3 times the load current. Switch fuse units can be installed on metal-clad switchgear.

A complete range of Fuse Switch & Switch Fuse units are offered to suit varied power distribution applications. The heavy duty Fuse Switches are fully type tested with short circuit breaking capacity of 80 KA at 415V suitable for utilisation category AC-22A/ AC-23A. Four frame sizes cover the full range. The Switch Fuse units are suitable for utilisation category AC-22A.

The accurate current limiting operation and high breaking capacity office has resulted in a number of ingenious combination of switches and fuse to get an economical unit combining the best performance of each.

Features of Fuse Switches

i. Double break with side handle operation

ii. Positive indication of contacts

iii. Suitable for surface mounting

iv. Door interlock facility

v. Sheet steel enclosure duly phosphatised and powder painted

Features of Switch Fuses

i. Side handle operation

ii. Suitable for surface mounting

iii. Sheet steel enclosure duly phosphatised and powder painted

iv. Provision of conduit knockouts and detachable gland plates.

Construction of Fuse Switch

Fuse Switch units are fitted with sturdy side operating handle which drives the quick make break mechanism incorporating operating springs. Liberal sized silver plated terminals, suitable for aluminium cable/bus-bar termination, are provided with terminal cover shields to prevent any accidental contact with live metal parts. Positive ON-OFF indication is provided on the switch door.

1. Contacts

Contacts are made of electrolytic copper, electro-plated with silver, for better contact and greater resistance to corrosion. Specially designed female contacts ensure low contact resistance and better arc-control.

2. Fuses

Fuse switches are designed for use with HBC Cartridge fuse links conforming to IS:13703.

3. Enclosures

The enclosure is made of sheet steel, rust protected, phosphatized and powder coated. They are fitted with removable top and bottom end plates provided with knock-outs for bus bars/cables entry. Front accessible door, fitted with dust- excluding gasket, is interlocked to prevent opening when the switch is in 'ON' condition. They are suitable for surface mounting.

Construction of Switch Fuse

Switch Fuse Unit comprises of vitreous steatite porcelain rewireable fuses or HBC fuse fittings complete with their conducting parts. The switch is fitted with sturdy side operating handle with quick make-break type mechanism.

1. Contacts

Contacts are made of electrolytic copper, silver-plated. The fixed contacts are provided with removable shield.

2. Fuses

Switch Fuse units are provided with rewirable fuse or HBC Fuse Links.

3. Enclosures

The Enclosure is made of sheet steel duly phosphatised and power-coated. They are provided with conduit knock-outs and have detachable gland plates. Door interlock is provided to prevent opening when the switch is in 'ON' condition.