Rockwell Automation 1560E SMC Flex Smart Motor Controller - Manual (Page 133)

Troubleshooting 9-15
SCR Replacement Procedure (cont.)
Important: DO NOT loosen any of the nuts on the fiber rods on either
side of the clamp bars. They must remain as they are to maintain squareness.
See Figures 9.6, 9.9 and 9.15.
2. Loosen the clamp by rotating the centre nut below the indicator washer
at the top end of the clamp. Refer to Figures 9.6, 9.9 and 9.15.
As the centre nut is rotated, the entire spring assembly is retracted
from the top heatsink. Continue to retract until there is a gap of
approximately 6 mm (0.25 in).
3. The heatsinks may now be spread apart to allow removal of the SCRs.
4. Apply a thin film of Electrical Joint Compound (supplied) to both
faces of the new SCRs.
5. Place the new SCRs in position starting from the top and pushing the
heat sinks together as you proceed down the stack. Make sure the
SCRs are positioned and oriented properly. Refer to Figures 9.7, 9.10,
and 9.16.
6. Ensure that the SCRs are properly seated on the locating pins in the
heatsinks and rotate each SCR so that the leads are oriented toward the
front right side of the assembly.
7. Advance the centre nut until the spring assembly engages the top
heatsink. Make sure the clamp is properly seated on the locating pins
in the top and bottom heatsinks before beginning to tighten.
8. Tighten the centre nut until the indicator washer becomes loose with
some friction. The clamp is now at the proper force and must not be
clamped any tighter. If the indicator washer becomes too loose (no
friction), back the centre nut off slowly until the washer is loose with
some friction.
9. Replace the shorting bar. Torque hardware to 30 N-m (20 ft-lb). For
3/8-in. hardware in the 'T' slots of aluminum heatsinks, the recommended
torque is 22 N-m (16 ft-lb). Do not overtorque these connnections as
the slots will be damaged and the connection will be compromised.