Troubleshooting Electric Deck Crane with VFD Drive

Intro

This Log Carrier is equipped with four MacGREGOR fully electric cranes, type GLBE 3626-2/2826gr/3026log. Unlike regular electro-hydraulic cranes, these cranes are equipped with a Variable Frequency Drive (VFD), and the winches are driven by electric motors instead of hydraulic motors. The Drive system uses Siemens inverters and a Sinamics CU320 control unit, utilizing CAN-Bus communication.

The CC3000 crane control system allows features such as automatic Anti-Collision monitoring and Auto Team Function, which enable 2 cranes to operate in twin crane mode.

BACKGROUND

The vessel was discharging bulk cargo in Thailand using grabs when the cranes developed faults and alarms that interrupted cargo operation. The crew reported that the alarms had existed for a long time already.

ALATAS’ SOLUTION

Due to the complexity of the cranes, the crew could not troubleshoot the faults. Hence a Senior Crane Engineer with Siemens VFD Drive troubleshooting experience was mobilized from Alatas Singapore to attend in Ko Si Chang, Thailand on an urgent basis to investigate and rectify the faults.

Job Scope

The following faults were found and rectified promptly by our crane specialist:

CAN-BUS Wiring Fault:

• Measured and checked CAN -BUS system and found no communication to the vessel switchboard (used for power limitations). Start loop- checking the cables from the engine room going to all cranes. Isolated the Can Bus Repeaters and found that the existing wiring from T80 going to crane Nr. 4 slip ring is wrongly connected to the terminals and mixed-up wiring is going to the crane slip ring. Due to wrong terminations, the CAN-BUS system cannot recognize the NODE ID hence, causing a system error. This was corrected.
• Found another wrong wiring connection going to crane Nr. 1 (CAN H and CAN L connections). This too, was corrected.
• After correcting all the electrical connections all alarms and errors regarding the power limitations returned to normal.

Rectifying Additional Errors and Alarms:

• The remaining alarms were inspected and rectified one by one, such as anti-collision, high oil temperature alarm, intermittent radius indication alarms, etc.

Anti-Collision Alarms:

• Some of the alarms are standard alarms like hoisting and luffing limitation generated by the anti-collision system when 2 cranes come too near to each other. They reset automatically once the cranes are back inside their safe working area.
• This is a fact that the Stevedores did not know, they wrongly assumed the cranes were faulty.

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