How to Select a Suitable Motor

Before Starting VFD take the following precautions

When using the AC Motor Drive to operate a standard
3-phase induction motor, take the following precautions:
  • The
    energy loss is greater than for an inverter duty motor.
  • Avoid
    running motor at low speed for a long time. Under this condition, the
    motor temperature may rise above the motor rating due to limited airflow
    produced by themotor’s fan. Consider external forced motor cooling.
  • When the
    standard motor operates at low speed for long time, the output load must
    be decreased.

 The load tolerance of a standard motor is as follows:



  •  Pole-changing (Dahlander) motor:
The rated current is differs from that of a standard
motor. Please check before operation and select the capacity of the AC motor
drive carefully. When changing the pole number the motor needs to be stopped
first. If over current occurs during operation or regenerative voltage is too
high, please let the motor free run to stop (coast).
  • Submersible motor:
The rated current is higher than that of a standard
motor. Please check before operation
and choose the capacity of the AC motor drive
carefully. With long motor cable between
AC motor drive and motor, available motor torque is
reduced.
  • Explosion-proof (Ex) motor:
Needs to be installed in a safe place and the wiring
should comply with the (Ex)
requirements. Delta AC Motor Drives are not suitable
for (Ex) areas with special
precautions.
  • Gear reduction motor:
The lubricating method of reduction gearbox and
speed range for continuous operation
will be different and depending on brand. The
lubricating function for operating long time
at low speed and for high-speed operation needs to
be considered carefully.
  • Synchronous motor:
The rated current and starting current are higher
than for standard motors. Please check before operation and choose the capacity
of the AC motor drive carefully. When the AC motor drive operates more than one
motor, please pay attention to starting and changing the motor.
  • Power Transmission Mechanism

Pay attention to reduced lubrication when operating
gear reduction motors, gearboxes, belts and chains, etc. over longer periods at
low speeds. At high speeds of 50/60Hz and above, lifetime reducing noises and
vibrations may occur.
  • Motor torque
The torque characteristics of a motor operated by an
AC motor drive and commercial mains power are different.

Source: Delta VFD B Series manual.

Leave a Reply