Alpha Technologies Cordex HP CXRF 48-12kW - Manual (Page 41)

39 9400000-J0 Rev C
10.5.2 12kW Rectifier MOV Replacement
Refer to "2.3 Part Numbers and List Options" on page 8 for the part number of the replacement MOV.
The MOVs (metal oxide varistor) are used to protect the power modules from power line surges and surges
caused by lightning strikes. High capacity surges may permanently damage MOVs but they are easily replaced
in the field using the following procedure:
1. Shut off the unit and unscrew the front fastener that secures the 12kW power module to the shelf.
2. Slide the module out of the shelf and wait ten minutes for the module capacitors to discharge.
3. Remove the six screws that secure the back panel to the module.
4. Slide the back panel downwards to release it from the top of the chassis.
5. Unscrew and remove the defective MOV board.
6. Decontaminate the area and unit with a flux remover or similar cleaning compound. This is done to remove
any metallic particles or carbon that may have been deposited when the MOV failed.
7. Install the replacement MOV PCB following the preceding steps in reverse order.
MOV PCBs
1 screw
4 screws
1 screw