250 A switch-disconnector body for BS fuse protection
The GS1NBR3: This is a TeSys GS fuse switch disconnector body, 3 poles, accepting BS-type fuses (sizes, B3). Rated operational current is 250 A at 400 V in AC-23A and AC-23B duty – the AC-23B rating covers occasional motor switching with inrush, while AC-23A covers frequent switching of resistive or mixed loads. For DC applications, the same body delivers 200 A at 440 V with two poles in series per phase (DC-23A/B).
Breaking and making capacity – fault handling
Breaking capacity is 2000 A at 400 V AC-23B; making capacity is 2500 A at the same voltage. Short-circuit withstand rating is 80 kA – the body is designed to coordinate with upstream BS fuses rated 250 kA making capacity at 400 V. The switch-disconnector itself does not interrupt faults; the fuses do, and the body must survive the let-through energy.
Panel fit and environmental limits
Dimensions are 5.7 in deep, 9.8 in wide, 7.7 in high – the body mounts on a plate or rail. IP20 with the terminal cover fitted (IEC 60529) means it is touch-safe inside an enclosure but not protected against dripping water. Operating temperature range is -20 to 70 °C, with fire resistance of 960 °C on the body and 850 °C on the fuse cover per IEC 60695-2-1. Power circuit terminals accept 95…240 mm² flexible cable; tightening torque is 25 N·m on both power and control terminals.
Durability and standards
Mechanical durability is 10,000 cycles; electrical durability is 1,000 cycles in AC-23A/B and 200 cycles in DC-23A/B. The body complies with IEC 60269-1, IEC 60269-2, and IEC 60947-3. Rated insulation voltage is 750 V AC, impulse withstand voltage is 8 kV. Conventional free-air thermal current is 250 A at 40 °C.