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Motor Cooling
Motor cooling will be dependent upon motor selection. Premium efficiency motors will generally provide cooling from a shaft
mounted fan. Typical motor type would be Totally Enclosed Fan Cooled (TEFC). Motors of this type should use a maximum turndown
of 10:1 as low speed operation leads to inefficient fan cooling, resulting in premature bearing and winding failure. Inverter Duty and
Vector Duty motors are designed to be used for lower speed (higher turndown) applications and generally are Totally Enclosed Non
Ventilated (TENV). Cooling is provided via convection and a large heat sinking motor enclosure.
Motor to Controller Cable Distance
Motor to controller distance in all cases should be minimized. AC drive motor control waveforms are formed from a DC bus and
are "chopped" to create an AC control waveform. These waveforms create motor wiring high voltage spikes. These spikes are made
worse with longer cabling (due to impedance mismatch and the corresponding reflected waveform, dv/dt). These reflected waveforms can
easily double the voltage seen by the motor windings.
Cable Length
MPC VECTOR to motor less than 25
feet (7.6 meters)
MPC VECTOR to motor greater
than 25 feet (7.6 meters)
NOTE: the maximum pump to controller distance is 100 feet (30.5 meters). If longer distances are required, please contact the
factory. Line and load reactors can be utilized to allow operation over longer distances.
Minimum Required Motor Turndown Rating
Use ratings guidelines in chart above
4:1 or 10:1 turndown
Must use 10:1 inverter duty
rated motor
72
20:1 turndown
Consult factory
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Troubleshooting
