GE AKR-30 Series Maintenance Manual page 41

SECTION 9-Fused Breakers
There are two types of fused breakers; AKRU 30, 800
ampere frame and AKRU 50, 1 600 ampere frame. Except
for the open fuse lockout device and the integrally­
mounted fuses on the upper studs, the AKRU-30 and -50
breakers are identical to the unfused AKR-30 and -50
models. Overcurrent trip devices are the same for both
types.
9.1 FUSE SIZES AND MOUNTING
6
Table lists the range of fuse sizes available for these
breakers. The Class L fuses are mounted as shown in Fig.
51 . Other than the SOOA size, which has a single mounting
hole per tang, each L fuse tang has two holes sized for
one-half inch bolts.
Class fuses rated 300 thru 600A have one mounting
J
hole per tang. The 300, 350 and 400A sizes require copper
adapter bars per Fig. 52.
TY
FIG . 51 PI CA L MOUNTI NG CLASS L
-
FUSES
9.2 SPECIAL 2500A FUSE FOR AKRU-50
This fuse provides a melting time-current characteristic
that coordinates with 1 600A trip devices. Compared physi­
cally 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 spac­
ing ; a special primary disconnect assembly mounts directly
on the outboard tang of the fuse. Considering their unique
mounting provisions, when replacing these fuses the fol­
lowing procedure should be adhered to (Refer to Fig. 53):
a) Remove the primary disconnect assembly from the
fuse tang, accomplished by first loosening the two keys
via their holding screw and pulling them u pward and out.
After the keys are removed, pull the disconnect assembly
off the end of the fuse tang.
This removal
N OT E :
disconnect's clamping force adjustment.
b) Remove the upper barrier.
c) Detach the inboard end of the fuse by removing the
two 1 /2 inch - 1 3 bolts. A ratchet and socket with a short
extension will be requied.
d) Remove the heat sink.
e) Remove the fuse.
f) Install the new fuse by reversing the disassembly
procedure. Ensure that the mating faces of the fuse and
heat sink are clean.
ADAPTER B ARS (COPPER)
FIG. 52 300 THRU 600 AMP CLASS J
-
FUSE MOUNTING
does not disturb the
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