An issue was observed in which the North Aux hoist failed to travel West when commanded to, but the East motion was functioning. The North Aux hoist Trolley was stuck in a position up against the East wall.

Present during troubleshooting: Adam N, Maico D, Tom K, Allon M, Travis C

After troubleshooting, it was determined that:

• There were no fault messages on the HMI display relating to this issue
• The HMI indicated "Bridge Not in North Limit and/or Auxiliary Trolley North Not in East or West Limit" - the Bridge was not in the north limit as described, and this message implies the PLC thought the North Aux hoist was somewhere along the middle of its travel
• The West run signal was reaching the remote receiver from the crane pendant
• The West and East run signals were correctly reaching their respective input pins on the VFD (DI1, DI2)... upon swapping wires and commanding it to run East, the West direction still did not function
• The VFD was displaying the correct output frequency information on its display when commanded to run East, but not west
• The limit switch was not related to this issue

Upon swapping out the VFD with the working one from the South Aux hoist, the North Aux hoist Trolley was able to move both East and West, as normal. It was therefore determined that the VFD had failed and must be replaced.

Current state of system as of July 3, 2020:

• The North Aux hoist is fully functioning (contains VFD from South one)
• The South Aux hoist is disabled (no VFD, breakers shut off)
• The North Aux hoist limit switch flag has been temporarily bypassed to allow for crane work in the target hall (not a safety issue - extended bumpers are installed and the regular bridge limit switches are functioning normally... this is only to allow the bridge to run its full length of travel when the North Aux hoist is at its fully East position)

Next steps:

• Adam Newsome requested quote for replacement drive (Delta Electronics TDN007E1100WM0) - will advise when replacement arrives
• Install replacement drive into South Aux hoist upon arrival (note: check EMC level modification)
• Verify entire system functioning as normal
• Reinstall North Aux hoist limit switch flag