A canned motor pump uses an integrated electric motor and pump assembly. The motor rotor is connected directly to the pump shaft and impeller, so the pump does not need an external coupling or separate drive shaft arrangement. This compact construction is one of the main differences between a canned motor pump and a conventional motor-pump set.
Direct Integrated Motor Drive
The rotor and impeller rotate as one integrated assembly. Eliminating an external coupling reduces alignment work and helps keep the overall unit compact. The stator winding remains isolated from the pumped liquid by the stator liner, while the rotor operates inside the process side of the motor.
50 Hz and 60 Hz Operation
Supply frequency directly affects synchronous motor speed and therefore pump hydraulic performance. A pump selected for 50 Hz should not simply be operated at 60 Hz without checking the resulting speed, flow, head, power requirement and motor design.
YUEMAX can provide both 50 Hz and 60 Hz canned motor pump solutions. For replacement projects, the original motor frequency, voltage and rated speed should be included with the nameplate data.
Variable-Frequency Drive Considerations
Variable-frequency operation can be evaluated for some applications, but the allowable frequency range should be confirmed rather than assumed. Motor cooling, internal liquid circulation, bearing lubrication, hydraulic duty and minimum operating speed can all affect whether VFD operation is suitable.
- Confirm the intended minimum and maximum frequency
- Check motor current and power margin
- Review pump curve changes with speed
- Confirm internal circulation remains adequate
- Review low-flow or minimum-flow limits
Motor Cooling and Internal Circulation
Unlike an air-cooled external motor, many canned motor pumps rely on the pumped liquid to remove heat from the motor cavity. This makes fluid properties and circulation design important to motor reliability. High-temperature, volatile or viscous liquids may require special circulation or separation arrangements.
Data Required for Electrical Selection
- Voltage and phase
- 50 Hz or 60 Hz frequency
- Required flow and head
- Fluid name and operating temperature
- Continuous or intermittent duty
- VFD frequency range, if required
- Original motor data for replacement projects
The hydraulic operating point and motor rating should be checked together. See the pump performance curve guide for more information.