ABB AKD-10, Installation And Maintenance Manual

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Table 9
40 - Special 2500A Fuse for WPF-16
This fuse provides a melting time-current characteristic that coordinates with 1600A trip
devices. Compared physically with a 2500A NEMA Class L fuse, the special fuse is more
compact (shorter); its tangs are specially configured and offset to achieve the required
pole-to-pole fuse spacing; a special primary disconnect assembly mounts directly on the
outboard tang of the fuse. Considering their unique mounting provisions, when replacing
these fuses the following procedure should be adhered to (Refer to Fig. 53):
a) Using proper safety procedures and wearing required Personal Protective Equipment
(PPE), remove breaker from compartment, and place it on a solid work surface in a well lit
location.
b)Procedure to uninstall Primary Disconnects:
1. To uninstall the primary disconnects, remove the Adjusting nut from one of the long
bolts holding the primary disconnect assembly together
2. Carefully slide out the bolt while removing the flat washer, spring, upper retainer, bowtie
spacers, lower retainer, and fingers from the bottom of the assembly.
3. Do the same for the other assembly bolt and components.
4. Slide off the retainer clips.
5. Take off the main retainer from the stud.
6. Slide the main retainer over the stud.
7. Set a pair of bow-tie spacers into a pair of fingers, place a pressure plate retainer over
the spacers to hold them in position, and then turn the subassembly over. Hook them
into the main retainer.
8. Slide a long bolt through the hole in the retainer, between the finger, and then through
the clip and stud spacer.
9. Hold the bottom finger subassembly in place.
10. Place two fingers around the bolt from the top, hooking the fingers into the main
retainer. Then place a bow-tie spacer in each finger and hold them in position with a
pressure plate retainer.
11. Place a spring, bushing, and flat washer over the bolt, then secure with the Adjusting nut.
12. Repeat Steps 7 through 13 for each set of fingers.
13. Adjust the nut to get a spacing of 0.766—0.797 inch for AKRU-50 between the top of
the upper retainer and the bottom of the flat washer.
Fuses For WPF Breakers
72 C