The motor cooling is guaranteed by a “water jacket” circulating between the stator core and the outer frame, which allows a more effective heat exchange resulting in a higher power per weight ratio, therefore reducing the size of the motor. This system is ideal for variable speed applications since the thermal efficiency is optimized even on reduced speeds and where space is a concern.
WGM motors can be used in several segments of the industry, especially driving machines that require constant torque even at low speeds. Thus, they are the right choice for applications in high temperature environments, limited space availability for motor operation or motor submitted to dusty environments. This solution has a wide range of applications. Not only on the marine and offshore segments, but in all applications where water cooled motors are beneficial. In the marine segment, for instance, when operating at DP (Dynamic Position), the vessel’s thruster motors can withstand long periods of operation at very low speeds.
Under this operation condition, standard cooling methods that rely on shaft mounted fans have the heat exchange capacity greatly reduced since the cooling is directly dependable on motor speed. The “water jacket” solution has its cooling efficiency guaranteed throughout the speed range as the heat removing capacity is independent of motor speed.
The “water jacket” cooling system consists of heat dissipation through the circulation of water through the channels inside the frame which provide an even and continuous flow. The water is supplied by an external system and enters the motor through the connections on the motor end bell (drive end or non drive end). The passage of water from the end bell to the frame is made through mechanically shielded hoses which avoid the risk of internal leakages.
In addition to exceptional cooling capacity as a result of even distribution of internal temperature, this system considerably reduces the motor noise level and practically eliminates heat exchanges from the motor to the ambient when compared with fin cooled motors.
In 2008, several water jacket cooled motors were sold in the domestic and international markets. Edison Chouest Offshore Who currently acquires from WEG the complete electrical package for all the Brazilian built vessels, has already purchased several units of WGM motors that will be used on supply vessels being built in the USA.
Output power: 315 to 2.800kW
Frame sizes: 315 to 560 (IEC)
Voltages: 690 V to 6600 V
Number of poles: 2 to 8