One of your motors has
just stopped running and your production has stopped. Is the problem mechanical
or electrical? Is it the drive, overload, connections, capacitors or load?
Finding the cause could take hours.
Could you have seen it
coming? Could you have identified the potential fault in advance, correct the
issue through scheduled maintenance and avoided the unplanned
From the day you install
a motor, it is in the process of failing. The only question is when. According
to an EPRI study, almost half of all motor failures are electrical in nature
(the rest are mechanical). The majority of electrical motor faults start as
shorted turns with the windings. In addition, poor connections, winding
contamination and rotor issues all lead to motor failure.
Is a technology that lets you
examine the electrical health of a motor through measuring multiple electrical
properties of the windings. The Motor Circuit Analyzer performs five
measurements on each of the three winding phases:
- Three separate high
accuracy bridges measure winding resistance, impedance and
- A low voltage AC
signal is applied and the resulting phase angle is measured.
- A mulitple frequency
current response test (I/F) is performed.
- Insulation resistance
to ground is measured at either 500V or 1000V.
In a healthy motor all of
these measurements are balanced. When one or more is out of balance, you have a
clear indication of where the fault most likely is. For example if all
measurements except resistance are balanced, a loose connection is indicated.
Unbalanced in the phase angle or I/F test indicates shorted turns within the
windings. You can also isolate and identify rotor faults and eccentricity in
assembled motors without run testing under load.
Extensive research and
field tests have shown that the guidelines for detecting fault conditions are
the same on any size and type of device - our instruments have successfully
evaluated 29MW synchronous
machines, tool machine servos, induction motors of all sizes and voltages and
even pad and pole mounted distribution transformers. And you can rely on the
results - there are virtually no "false" positives or negatives.
A software program develops a report that
will indicate the condition of the motor. The program will stipulate the area of
concern on the motor or indicate good winding which means the motor’s condition
are done from the motor control center, through cable runs of 100 metres or more. All tests
are low voltage and totally non destructive, so there is no danger of
damaging sensitive equipment. A test takes less than fifteen minutes and can show you
turn, coil and phase-to-phase faults, open phases, poor connections,
contaminated or burned windings, grounded windings and connections or a motor
that is perfectly healthy.
Some facts about
- They usually start in
the end-turns of the windings where stress is greatest and the insulation
system is weakest.
- They start small and
escalate over time.
- They sometimes
progress to ground fault.
- They always end in
- You can't detect them
with a Megohm meter or DMM until the motor has totally
Motor Circuit Analysis can detect & trend the
- Resistance- Indicates loose or poor connections
- Inductance & Impedance- Indicates overheated or
- Phase Angle & Current/Frequency- Indicates turn to
turn or coil to coil
- Insulation Test-Indicates ground faults or phase to phase