BOK / BPOK / BOP / BPOP — low-voltage marine induction motors, squirrel-cage and wound rotor, 55–1800 kW

BOK / BPOK / BOP / BPOP — low-voltage marine induction motors, squirrel-cage and wound rotor, 55–1800 kW

Country: Serbia · Model: BOK / BPOK / BOP / BPOP

Low-voltage marine induction motors BOK / BPOK with a squirrel-cage rotor of 200–1800 kW and BOP / BPOP with a wound rotor of 55–1000 kW are rated for 230–690 V. A frequency of 50 or 60 Hz matches typical ship networks, and the machines themselves are installed in engine rooms and on deck machinery, in ports, docks and on floating installations.

Designation: BOK, 2.BOK, BPOK, 2.BPOK, 2.BOKIT, 2.BPOKIT (squirrel-cage rotor); BOP, 2.BOP, BPOP, 2.BOPI (wound rotor)
Power: 200–1800 kW (squirrel-cage rotor); 55–1000 kW (wound rotor)
Voltage / frequency: 230–690 V / 50 Hz, 60 Hz
Shaft height (frame size): 315–500 (squirrel-cage); 280–400 (wound)

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Technical specifications

Designation	BOK, 2.BOK, BPOK, 2.BPOK, 2.BOKIT, 2.BPOKIT (squirrel-cage rotor); BOP, 2.BOP, BPOP, 2.BOPI (wound rotor)
Power	200–1800 kW (squirrel-cage rotor); 55–1000 kW (wound rotor)
Voltage / frequency	230–690 V / 50 Hz, 60 Hz
Shaft height (frame size)	315–500 (squirrel-cage); 280–400 (wound)
Number of poles	4–6
Insulation class	F
Protection degree	IP23
Cooling	IC 411 (squirrel-cage, per website data); IC 01 (wound)
Mounting	IM B3, V1
Connection dimensions	IEC 60072
Standard	IEC 60034-1

Specifications are taken from the manufacturer’s technical documentation. Updated 11/06/2026.

Description

The squirrel-cage line consists of the BOK, 2.BOK, BPOK, 2.BPOK, 2.BOKIT and 2.BPOKIT series on frame sizes with a shaft height of 315–500. The wound-rotor line includes the BOP, 2.BOP, BPOP and 2.BOPI with frame sizes of 280–400. All machines are made in 4- and 6-pole versions with class F insulation, foot-mounted IM B3 or vertical IM V1. Protection degree IP23 corresponds to a protected design for engine rooms. Wound-rotor motors are cooled to scheme IC 01, that is, open self-ventilation. Squirrel-cage machines drive ballast, cargo, fire and cooling pumps, compressors, engine room fans and thrusters. A wound rotor is needed for cargo winches, windlasses and deck cranes, and also where the starting current has to be limited because of the small power of the ship's power plant. Connection dimensions comply with IEC 60072, general requirements with IEC 60034-1.

How to choose

First determine the rotor type by the nature of the machine, then the power and shaft height within the corresponding line. For squirrel-cage machines the manufacturer's table states IC 411 cooling, which is atypical for IP23, so the ventilation scheme is clarified when making an enquiry. For offshore oil platforms there is a separate 2.SRZKIT series at 15–1500 kW and 400–690 V.

Request a price and lead time

BOK / BPOK / BOP / BPOP — low-voltage marine induction motors, squirrel-cage and wound rotor, 55–1800 kW. We reply within one business day.

Or email office@usk.ua or call +38 (044) 339-50-20.

FAQ

Do the BOK and BOP motors have marine register approval?

There is no data on classification society approvals. For building or repairing a ship under register supervision, type approval is requested from the manufacturer before the contract is concluded.

Where on a ship can a motor with protection degree IP23 be installed?

IP23 corresponds to a protected design, so the motor is installed in engine rooms and enclosed spaces, not on an open deck.

When should a BOP wound-rotor motor be taken on a ship instead of a squirrel-cage BOK?

A wound rotor BOP, 2.BOP, BPOP or 2.BOPI is needed for winches, windlasses and cranes with heavy starting and speed control. It also limits the starting current when the ship's power plant has limited capacity.

What is the speed of the BOK / BPOK marine motors?

The motors have 4 or 6 poles, so at 50 Hz the synchronous speed is 1500 or 1000 rpm. On a 60 Hz network both values increase by one fifth.