Allen-Bradley 1512B, User Manual

Page: 64 / 108

64 Rockwell Automation Publication 1500-UM055I-EN-P - December 2021
Chapter 4 Maintenance
7. If an infrared window is not available, complete the following steps:
a. Perform a visual inspection of the isolation switch.
Look for dried, dark-colored, hardened grease or pitting on the incoming
line stabs.
b. Using a micro-ohmmeter, take resistance measurements as close as
possible to the isolation switch and load connections (from the main
power bus to the top of the power fuses).
Measurements greater than 150 μΩ will prompt hardware changes.
See
Recommended Corrective Action on page 64 .
Recommended Corrective Action
1. Replace all three movable blades.
• 400/600 A isolation switch: torque to 11 ft•lb (14.9 N•m)
• 800 A isolation switch: torque to 19 ft•lb (25.8 N•m)
2. If there is hardened, dark colored grease or pitting on the isolation
switch terminals, replace the incoming line stabs.
Pitting can indicate incorrect adjustment of the isolation switch
auxiliary switches.
Contact technical support for assistance.
Isolation Blade Switch
Adjustment
1. Insert a screwdriver in the Isolation Switch Defeater, push down and
hold at the bottom position.
2. Actuate the Isolation Switch Operating Handle from Open (black) to
Closed (red) in a continuous movement.
Do not use excessive force or speed in closing the switch. This will cause an
incorrect test result.
A healthy isolation switch has a thin layer of clear lubricant.
ATTENTION: Do not add grease. Do not remove existing grease
and apply a different lubricant.
ATTENTION: Complete the Power Lockout procedure of the main
power bus before servicing equipment. Verify with a hot stick or
appropriate voltage measuring device that all circuits are voltage free.
Failure to do so may result in severe burns, injury, or death.
WARNING: Use suitable personal protective equipment (PPE) per local
codes or regulations. Failure to do so may result in severe burns, injury, or
death.