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Motor Diagnostic Definitions
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Motor Diagnostics: Tools, instruments and software applied
to trend or evaluate the condition of an electric motor’s electrical and mechanical environment. This definition will be used to cover all methods of rotating machinery testing.
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Mechanical Motor Diagnostics: Vibration, Infrared and Ultrasonics, for instance,
will be covered under tis sub-group. Each
of these tools detect, primarily, the mechanical condition of the rotating machinery with
some ability to detect and identify electrical issues.
This definition covers those instruments and software capable of BOTH trending and diagnosis of faults through
either a single set of readings (diagnosis) or a series (trending) that is repeatable.
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Electrical Motor Diagnostics: Motor circuit analysis and
motor current signature analysis only. These tools are designed to, primarily, detect the electrical condition of the motor’s electrical environment either energized or de-energized.
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Test Motor Diagnostics: Multi-meters, insulation to ground
testing, surge comparison testing, and similar testing used to evaluate
individual components of the electric motor’s condition. These test tools can also include micrometers, growler (rotor) testing, bar to bar
tests (DC mac
h
ines), etc. Generally, equipment
used to check the condition of rotating machinery that will not necessarily be trend-able or repeatable and that may be potentially
destructive.
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Motor Circuit Analysis (MCA): Electrical Motor Diagnostics
of de-energized rotating machinery. At the time of t
h
e MDMH study, there are two manufacturers of MCA devices that use very different approaches. One is a portable (brief case
and lap top) RCL-based instrument, relatively expensive, and provides readings
of resistance, inductance, capacitance and a battery of insulation to ground
tests. The other is a
hand-held impedance based instrument, communicates with
computer software, is relatively inexpensive, and provides readings of
resistance, inductance, impedance, phase angle, current/frequency response and insulation to ground testing.
The portable instrument requires a great deal of training and experience while the
hand-held instrument can usually be applied in a few
hours of self-training (Findings of UIC-ERC study).
The primary benefits of MCA include: Safety of de-energized testing (reference
NFPA 70E and OSHA for flash
protection in energized systems); The ability to isolate the condition of just the components being tested with
little to no interference from the outside environment. This allows the ability to troubleshoot individual components.
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Motor Current Signature Analysis (MCSA): Electrical Motor
Diagnostics of energized rotating machinery. At the time of the MDMH study, there are four major MCSA instruments on the
market. Three are portable (brief case and lap top) and one is
hand-held. All are three-phase instruments but approach
the ability to evaluate the condition of equipment differently. The primary difference in the instruments is demodulation. One
method relies upon Torque Demodulation, one on Current Demodulation, and the
hand-held and other rely upon a combination of Voltage and Current Demodulation.
Each
tool requires more extensive
hardware/software and diagnostic training and safety during data collection is a
primary consideration. Several of the manufacturers provide permanently mountable ports that can be located on the door of the
MCC/disconnect cabinet.
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