Case Study

The main hoist of a crane vessel capable of lifting more than 80 tonnes of load can now operate more precisely and accurately following the installation and commissioning of a heavy-duty Optidrive P2 variable frequency drive from Invertek Drives.

Nusa Maritime Pte has been upgrading the drives of the main hoists on a crane barge at Keppel Offshore and Marine’s shipyard in Singapore.

Replacing the existing variable frequency drives with a 160kW Invertek Optidrive P2 IP55 saw instant benefits in load capacity, precision control and protection from overloading.

Invertek Drives Singapore carried out the wiring modification for the panel in order to interface with existing crane control.

“The existing inverter on the floating crane had become faulty and we were approached to provide a solution using an Invertek VFD which has been proven in heavy duty and marine sector environments,” said Henry Beh of Invertek Drives Far East.

“The P2 was perfect due to its heavy-duty capacity. After installation we undertook a load test up to 90 tonnes and our clients were impressed with the immediate capability in smooth speed adjustment of the hoist motors which lift a range of load weights.”

The P2 provides 150% overload for 60 seconds as standard which ensures it is suitable for all heavy-duty applications. Combined with the IP55 enclosure, the drive is capable of working in some of the harshest environmental conditions, including those in the marine sector.

Crane applications require high starting torque due to the heavy loads, with smooth motor operation throughout, including smooth start and stopping, and motor holding brake control.

Key benefits of the Optidrive P2 in such applications include dedicated hoist mode operation with motor holding brake control algorithm; up to 200% torque from zero speed and multiple preset speed or variable speed operation.

Henry added: “The installation and commissioning of the electric system on the vessel’s crane was enhanced through the use of the Optidrive P2 with greater precision as well as being much more accurate through the smooth control.”

The work included ensuring the commissioning passed Minister of Manpower approval for cranes and interfaced with the existing control system, alleviating the need for any other changes in the control process.