WTHB Fuse Switch Disconnector for Three Phase Distribution
The WTHB combines a switch and a fuse carrier in one body. The handle opens all three poles together, the fuses sit behind the carriers, and the whole device isolates a circuit and clears a fault in the same footprint. Four frames cover 160A to 630A.
Three Poles on One Handle
Each of the three poles has its own fuse carrier, and a single front handle operates them together, so a circuit cannot be left with two poles closed and one open. The carriers are reached from the front with the handle in the open position, which is the sequence an operator follows when a fuse is replaced. Terminals are studs closed with a hex nut at each pole.
Frames From 160A to 630A
Four sizes cover the usual distribution currents. Conventional heating current is 160, 250, 400 and 630A across the four frames, and the weights run from 1.2kg to 6.5kg, which is a fair guide to which frame is on the bench. Dimensions for each frame are given in the table on this page.
Making, Breaking and Fault Level
Rated making capacity is 10 times the operating current and rated breaking capacity is 8 times it, so the switch closes onto and opens a load without welding its contacts. The rated limit short-circuit current is 50kA, which is the figure the upstream protection and the fuse rating are coordinated against. Rated operating voltage is AC400V or AC690V, and DC1000V on the DC rating, at 50Hz with an insulation voltage of 800V or 1500V.
Life and Auxiliary Contact
Mechanical life is 5000 operations on the 160 frame, 3000 on the 250, 2000 on the 400 and 1500 on the 630. Electrical life at load is 1000, 600, 400 and 300 operations on the same frames, so a device used as a daily isolator and a device used as a fault-making switch are chosen differently. An auxiliary microswitch rated AC-15 at 230V 3A is available for a status signal to a controller. The body carries CE and CCC marking. Send the circuit current, the voltage and the quantity to WTAIELE for a quote.
