Page 44: of Marine News Magazine (July 2015)

Propulsion Technology

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Variable Frequency

Drives on Marine Deck Equipment

The modern variable frequency drive provides safety and ef? ciency with a quick payback for a slightly higher initial cost.

By David Hughes n the past decade, many advances have been made in When starting an electric motor across-the-line the mo- both the function and economy of variable frequency tor will start abruptly and with full voltage. This voltage

I drives (VFDs). VFDs can have many advantages when subjects the motor to a high starting current of approxi- applied to marine deck equipment such as winches, cap- mately 600% of full load current until the motor reaches stans, and hoists. Typically, this equipment is started by its rated speed. A VFD will ramp the motor to full speed standard across-the-line motor starters. While these start- over a programmable period of time. This eliminates the ers are low cost and their use widespread they have inher- current spike associated with starting an electric motor and ent drawbacks when used on marine deck equipment. allows for a slow, controlled acceleration. The maximum

Many of these drawbacks can be mitigated by upgrading torque produced by the motor can also be limited easily from a standard motor starter to a modern variable fre- through VFD con? guration. This limits the operator from quency drive. overloading or stalling a motor. If equipment is frequently

July 2015

MN 44

Marine News

Marine News is the premier magazine of the North American Inland, coastal and Offshore workboat markets.