-
Open the ESA enclosure door.
-
Locate the circuit breaker on the bottom DIN rail inside the enclosure.
-
Flip the circuit breaker to the ON (closed) position.
-
Close the enclosure door.
-
Open the ESA enclosure door.
-
Locate the circuit breaker on the bottom DIN rail.
-
Flip the circuit breaker to the OFF (open) position.
-
Close the enclosure door.
ELECTRICAL DANGER
Before opening the enclosure for any reason other than operating the circuit breaker, de-energize, lock out, and tag out all power sources to the enclosure. Exposure to energized conductors inside the enclosure can cause electric shock and death.
The ESA toolkit in InsightCM™ provides a set of specialized viewers for analyzing motor electrical signatures. Each view targets a different aspect of motor health. The sections below describe how to interpret each view and what to look for.
The ESA Spectrum displays the frequency content of the motor current after a Fast Fourier Transform (FFT) converts the time-domain current waveform into amplitude versus frequency. The horizontal axis is frequency (Hz) and the vertical axis is amplitude, typically in decibels (dB).
The dominant feature is the line-frequency peak at the supply fundamental (50 or 60 Hz); fault information is carried in the smaller sideband and harmonic peaks distributed around and above it. Key interpretation guidelines:
-
Sidebands spaced at twice the slip frequency (2·s·f) around the fundamental point to rotor bar problems.
-
Peaks at multiples of running speed or at rotor-slot-pass frequencies indicate eccentricity.
-
Elevated peaks at line-frequency harmonics (120, 180, 360 Hz, etc.) generally reflect supply or power-quality issues rather than mechanical faults.
-
A rising sideband or harmonic amplitude over successive acquisitions is more significant than its absolute value — always evaluate the spectrum as a trend.
The ESA Envelope Spectrum (amplitude demodulation) is derived by extracting the modulation envelope of the current signal and then applying an FFT to that envelope. This removes the large line-frequency carrier and reveals low-frequency modulations that are difficult to see in the standard spectrum, making this view especially useful for detecting mechanical faults.
Look for discrete peaks at characteristic defect frequencies — running speed and its harmonics, gear-mesh frequencies, or the calculated bearing defect frequencies (BPFO, BPFI, BSF, FTF). Peaks that grow over time and align with a known fault frequency for the asset are the most significant indicators. Broadband elevation of the envelope floor without distinct peaks usually indicates increased random load variation rather than a specific developing fault.
The ESA Torque Waveform displays an estimate of the motor's instantaneous air-gap torque, computed from the measured three-phase voltage and current, plotted against time. A healthy motor driving a steady load produces a relatively flat, low-ripple trace. Interpret the waveform by relating the period of any repeating fluctuation to a mechanical event:
-
Pulsations at the running-speed period suggest misalignment, imbalance, or a coupling problem.
-
Pulsations synchronized to the driven equipment (pump vane-pass, fan blade-pass, or gear-mesh events) point to load-side disturbances.
-
A growing torque ripple over successive acquisitions signals a worsening mechanical condition even when the average torque is unchanged.
The Park Clarke view applies the Park/Clarke transform to the three-phase current, mapping the three currents onto two orthogonal axes (d–q) and plotting one against the other. For a healthy, balanced motor the resulting figure is a near-perfect circle centered on the origin. Interpret this view by examining the shape, thickness, and centering of the pattern:
-
A circle distorted into an ellipse indicates current unbalance — often a sign of stator winding faults, voltage unbalance, or a connection problem.
-
Thickening or fuzziness of the trace reflects modulation of the current by a developing fault.
-
An off-center pattern points to a DC offset or sensor issue.
The Phasor Diagram displays the magnitude and relative phase angle of each voltage and current phase as vectors on a polar plot. The three voltage phasors should be roughly equal in length and spaced 120° apart, as should the three current phasors. For an induction motor, each current phasor should lag its associated voltage phasor. Interpret the diagram by checking three things:
-
The three voltage and three current phasors are balanced in magnitude and evenly spaced.
-
The phase sequence is correct.
-
Each current phasor lags its associated voltage phasor (current should never lead).
NOTE:
A current phasor that appears to lead, or that sits approximately 180° from its expected position, indicates reversed current-sensor polarity on that phase. This can be corrected by enabling the Reverse Polarity setting for that sensor in the asset configuration — no field work is required.
The following sections describe each monitored fault mode, its appearance in the InsightCM™ data views, and the recommended response.
Description: Cracked or broken rotor bars disrupt the rotor current and produce pole-pass sidebands around the line-frequency peak in the ESA Spectrum. The sidebands are spaced at twice the slip frequency (2·s·f) on either side of the supply fundamental, and their amplitude relative to the fundamental grows as more bars break. In InsightCM™ this appears as a rising Rotor Bar Sideband feature value (less negative dB) and as visible sideband peaks in the ESA Spectrum.
Recommended Action: Trend the Rotor Bar Sideband feature against its alarm threshold. Confirm the motor is running under sufficient load (above 75% FLA), since the feature is not calculated accurately at low load. If sidebands are growing, plan a rotor inspection or testing during the next maintenance window.
Description: Coupling or shaft misalignment cyclically loads the motor once per revolution, modulating the current and torque at running speed and its harmonics (1×, 2×, sometimes 3× RPM). It is most visible as peaks at running-speed multiples in the ESA Envelope Spectrum and as periodic ripple at the running-speed period in the ESA Torque Waveform. A 2× running-speed component is a common misalignment signature.
Recommended Action: Check shaft and coupling alignment using laser or dial-indicator methods at the next opportunity, and inspect the coupling for wear. Correlate the ESA findings with available vibration data to confirm the mechanical source before scheduling corrective alignment.
Description: Eccentricity is a non-uniform air gap between rotor and stator, either static or dynamic. It produces peaks at the rotor-slot-pass frequencies and at running-speed sidebands around those slot harmonics in the ESA Spectrum. Growing peak amplitude over time indicates worsening air-gap variation.
Recommended Action: Verify mounting and check for soft foot, loose hold-down bolts, or a distorted base. Inspect bearings and bearing housings. Trend the relevant slot-pass peaks; rising amplitude warrants mechanical inspection.
Description: Looseness in the mounting, bearing housings, or driven-equipment connections allows components to move under load, producing irregular, often multi-harmonic content. It typically appears as a series of running-speed harmonics in the ESA Envelope Spectrum and as erratic or impacting fluctuations in the ESA Torque Waveform, frequently with a raised noise floor.
Recommended Action: Inspect and re-torque mounting bolts, hold-downs, and coupling fasteners. Check bearing housing fits and driven-equipment connections. Re-evaluate the ESA data after tightening to confirm the harmonic content has subsided.
Description: Stator winding problems — turn-to-turn shorts, phase imbalance, or insulation degradation — unbalance the three-phase currents. In the Park Clarke view this distorts the normally circular pattern into an ellipse, and on the Phasor Diagram it shows as unequal current magnitudes or uneven phase spacing. Severe faults also raise line-frequency harmonic and odd-harmonic content in the ESA Spectrum.
Recommended Action: Confirm the imbalance is internal to the motor and not caused by supply voltage unbalance (check the voltage phasors first). If currents are unbalanced with balanced voltages, schedule insulation-resistance and surge testing of the stator windings. Treat a developing stator fault as high priority, as turn-to-turn shorts can escalate quickly.
Description: Bearing defects (outer race, inner race, ball/roller, or cage) modulate the current at characteristic bearing-defect frequencies (BPFO, BPFI, BSF, FTF). These are best seen as discrete peaks in the ESA Envelope Spectrum. Rising peak amplitude at a calculated defect frequency indicates a progressing bearing fault.
Recommended Action: Match any envelope-spectrum peaks to the calculated bearing-defect frequencies for the asset to identify which element is affected. Trend the amplitude and corroborate with vibration or temperature data where available. Plan bearing replacement and lubrication review according to how quickly the trend is advancing.
Description: Power quality problems originate on the supply side — voltage unbalance, harmonic distortion, sags/swells, or rectifier/drive artifacts. They appear as elevated line-frequency harmonics (120, 180, 240, 360 Hz, etc.) in the ESA Spectrum and as unequal or unevenly spaced voltage phasors on the Phasor Diagram. Because the source is the supply, the same signature typically appears on multiple motors fed from the same bus.
Recommended Action: Examine the voltage phasors and voltage-side harmonics to confirm the issue is supply-related, and check whether other motors on the same bus show the same pattern. Investigate upstream sources such as drives, rectifiers, unbalanced loads, or loose connections. Address power quality at the source.
On a daily basis, the operator should review the alarm status of all monitored motor assets in InsightCM™. A once-per-day check of the alarm dashboard is sufficient to catch developing conditions that trend slowly, such as rising rotor bar sidebands or a declining power factor.
NOTE:
Configure email alarm notifications in InsightCM™ so that the operator receives an immediate alert when an alarm triggers between scheduled daily reviews. Daily dashboard checks and email notifications together provide both routine oversight and prompt warning of acute events.
Following any major overhaul, motor replacement, rewind, or extended outage, verify the InsightCM™ configuration before relying on the alarm system:
-
Confirm that the asset configuration — nameplate data, sensor mapping, and operating-state thresholds — still reflects the equipment as currently installed.
-
Allow the motor to run under normal load to collect representative data.
-
Review and reset alarm baselines after the work is complete. The motor's healthy signature may have shifted following an overhaul, so thresholds set against the previous baseline may produce false alarms or mask a real developing fault.
To initiate an immediate data acquisition outside the normal scheduled interval:
-
Navigate to the Device Configuration page in InsightCM™.
-
Select the desired device.
-
Open the Action menu and select Force Trigger.
-
Wait several seconds for the acquisition to complete.
-
Navigate to the Data Viewer to confirm data has been collected.