YASKAWA Varispeed-505WII - Main Circuit Thyristor Replacement

Main Circuit Thyristor Replacement
VS-505W 1, 230 V at 35
to
105
A,
460 V at 50 to
105
A
The unit uses a thyristor module consisting
of
two thyristors
.
Replace it
as follows .
1 . Remove snubber board (4PCB) mounting
screws (5)
and remove
snubber
board .
(Fig . 15)
2 .
Remove busbar mountingscrews and lead
clamping screwsconnected to thyristor
.
Remove
bus
bar and leads .
(Fig .
16) . In this case, mark
the terminals for identification .
3 .
Remove two thyristor clamping screws and
thyristor .
4 . Check the replacement module for type and
capacity, and reinstall it by reversing the dis-
assembly procedure,
identifying
the
terminals by
means of the marks made prior to disassembling .
Coat the thyristor mounting surface
with
joint
compound, JOINTAL Z made by Nippon Light
Metal Co . , Ltd .
SNUBBER
BOARD
.TG
SCREWS (5)
Fig .
13 Field Thyristor Assembly (230 V, 25 A)
Fig
. 14
With Snubber
Board Removed
Main Circuit Thyristor Replacement
VS-505
W 1, 230 V at 180 to 550 A, 460 V at 180 to
550
A
The
VS-505WIE uses a flat thyristor module as a
power module .

For 180 A and 260 A, one power
module is employed,
and for 420
A,
and 550
A,
three power modules are employed . Proceed as
follows .
1 . Remove the
clamping screws for thyristor
gate (C) and cathode (K) terminals (24 for 260 A
or below, and
8
for
420
A or more),
and free the
leads . Remove fuse mounting bolt(s) (3 for 260
A or below and 1 for
420
A or more) .

(Fig .
17)
2 . Loosen power module mounting bolts (7 for
260 A or below, 8 for
420
A or more) , and
remove
the power module .
THYRISTOR
CLAMPING -
SCREWS
S14UBBER
BOARD
MTG
SCREWS (5)
Fig . 15 Main Circuit Thyristor Assembly
(460 V, 105 A)
BUSBAR-
Fig .
16 With Snubber
Board
Removed