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Message ID: 46     Entry time: Wednesday, September 15, 2021, 15:10
Author: Adam Newsome 
Category: T-Hall Crane 
Type: Maintenance 
Subject: Hoist Broken Fault (actually: cable wrap issue) 

A fault occurred which presented as "114. Main Hoist Cable Broken (3200PX)". This occurred when a SEG block was suspended approximately 1 m off the ground.

Upon inspection, it was determined that the cable was in fact not broken, but wrapped around itself. There are no guides, and it is possible for the cable to double wrap if loaded in an usual fashion. This condition triggered the "Hoist Rocker Switch 1" sensor, 3200PX. The sensor is not visible or accessible from ground level, and could not be inspected, but it was confirmed that there was no 24 VDC PLC input at 30000EA:I.Data[7].0, as would be expected under normal operating conditions.

To rectify the issue:

  • The sensor was bypassed in the control panel by connecting wire 32001 directly to 24 VDC after confirming that there would be no adverse affects from doing this.
  • With careful supervision, the load was lowered, while watching the cabling.
  • The load was removed from the crane.
  • The hoist was then lowered to its extreme lower limit, and the cable unwrapped itself naturally as it was being lowered.
  • The sensor bypass was removed.
  • The sensor began functioning normally again when the wrapping issue was resolved.
  • The hoist was raised and lowered multiple times to confirm the cable wrapping issue was no longer present.

The crane is returned to its normally functioning state. Operators will keep a lookout for any more issues relating to the hoist cable. The crane will be inspected on Sept. 22, 2021.

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