1. General
1.1. Switches should be tested for disconnection function and to be called as switch disconnetor fuse.
1.2. The switches will conform to the requirements of IEC 947.1 and IEC 947-3 & IS 13947 part 1 and part 3
− the switches will have an impulse withstand voltage of 8 kV.
− the switches will have a rated operational voltage of 660V AC (50/60 Hz)
− the switches will have a short circuit withstand current (Icw) for 1 second of 2 kA for ratings up to 63A, 5kA up to 200A and 10kA beyond 200A upto 630A.
− the switches will have an impulse withstand voltage of 8 kV.
− the switches will have a rated operational voltage of 660V AC (50/60 Hz)
− the switches will have a short circuit withstand current (Icw) for 1 second of 2 kA for ratings up to 63A, 5kA up to 200A and 10kA beyond 200A upto 630A.
1.3. The switches will be of the positive contact indication type (according to IEC 947 – 3) to the exclusion of all other mechanisms. This function is to be certified by tests carried out by the constructor.
1.4. The range of switches will be available in 3 and 4 pole versions with full rated fused switched neutral within the same frame size.
2. Construction and operation
2.1. The switch operating mechanism will ensure rapid opening and closing (operator independent) and will conform to §2-12 of IEC 947-3. The closing of all poles, including the neutral, will be simultaneous as required by IEC 947-3.
2.2. To ensure positive contact indication as described in IEC 947-3 § 7-2-7.
− The operating handle will only indicate the O (OFF) position if the main contacts are actually separated. They will be achieved by design of the operating mechanism.
− The switches will be designed to be locked on the OFF position by padlock (with locking in
the ON position possible)
− The distance between open contacts will be greater than 8 mm.
− The operating handle will only indicate the O (OFF) position if the main contacts are actually separated. They will be achieved by design of the operating mechanism.
− The switches will be designed to be locked on the OFF position by padlock (with locking in
the ON position possible)
− The distance between open contacts will be greater than 8 mm.
2.3. Fuses should be isolated from both sides. Construction should prevent the possibility of live outgoing when incoming is live but there is no fuse mounted on the switch.
− These auxiliary contacts will be common with all of the range.
− The auxiliary contacts can easily be mounted on site without taking out any part like side
plate etc. and disturbing the mechanism.
− These auxiliary contacts will be common with all of the range.
− The auxiliary contacts can easily be mounted on site without taking out any part like side
plate etc. and disturbing the mechanism.
2.4. The electrical endurance will be that of category A. It will correspond to an AC23 operational category without a current derating at 415V ac for ratings up to 630A.
2.5. Fuse should be stationery during the switch operation.
3. Contact system
3.1. Contact system should have self wiping feature.
3.2. Separate arcing and current carrying zone to be provided for better thermal performance throughout the life of the switch.
3.3. Contact system should be designed in such a way that during high short circuit fault current the contact pressure increases and switch can withstand the fault. In no circumstances there shall be any repulsion between the contacts during short circuit
4. Installation and auxiliaries
4.1. The switches can be panel mounted.
4.2. The switches should come along with an operating handle with door interlock with defeat and padlock as standard.
4.3. Phase barriers for all switches should be available as standard. Terminal shield upto 63A should be available as standard. For higher ratings provision for fitment should be available.
4.4. Length of operating shaft should be adjustable continuously. This feature should come as a standard.
4.5. The switches should be able to take Aluminum termination.
5. Maintenance and site convertibility
5.1. The switches should be modular type. In case a single pole is damaged it should be possible to replace the entire pole instead of replacing the contacts inside.
5.2. It should be possible to convert 3 Pole to 4 Pole switch and vice versa.
5.3. In case it is required it should be possible to convert a switch from BS type fuse holder to DIN type fuse holder and vice versa at site