Bussmann Products

Class J and Class RK fuses have different characteristics: Class J fuses offer space-efficient design at 600V rating with excellent current limitation. Class RK fuses provide dual-element time-delay design for motor circuits with superior motor starting protection. Class RK1 offers highest current limitation, Class RK5 offers lower cost.

Use Class J for space-constrained applications. Use Class RK for motor circuits requiring time-delay.

Motor fuse selection: 1) Use Class RK or J fuses with adequate time-delay for motor starting; 2) Size at 125-175% of motor full-load current; 3) Consider service factor and starting conditions; 4) Coordinate with motor starter overloads; 5) Verify breaking capacity exceeds available fault current.

Size at 125-175% of FLA. Use time-delay fuses for motor circuits.

gPV (general Purpose Photovoltaic) certification per IEC 60269-7 is required for solar fuses. It indicates the fuse is tested for DC operation up to 1500V and can safely interrupt low overcurrents typical of PV faults. Standard fuses are not suitable for PV applications.

Always use gPV-certified fuses for solar/photovoltaic applications.

Breaking capacity must exceed maximum prospective fault current. Typical requirements: 100kA for standard distribution, 200kA for large industrial systems. Calculate based on transformer kVA and impedance. Add 25% margin. Bussmann offers fuses with breaking capacity up to 300kA.

Calculate fault current and select fuse with adequate margin.

Fast-acting fuses open quickly on overcurrent, ideal for protecting sensitive electronics and preventing wire damage. Time-delay fuses can withstand temporary overloads (motor starting, inrush) without opening. Use fast-acting for general circuits, time-delay for motor circuits with high starting currents.

Use fast-acting for general circuits. Use time-delay for motors and circuits with inrush.