Article

Why Electric Motors Sometimes Encounter Random Tripping That’s Hard to Recognize

Unexpected or “random” tripping of an electric motor can be one of the most frustrating issues in industrial operation. It often occurs without clear symptoms — the motor restarts and runs fine for hours or days before it happens again. These intermittent faults are difficult to trace but usually point to a combination of electrical, mechanical, and environmental factors.

1. Hidden Power Quality Disturbances

Root Cause: Sudden voltage dips, harmonic distortion, or transient imbalance from upstream equipment or unstable supply.
Effect: Protection relays and overload devices detect abnormal current surges, triggering unnecessary trips even when the motor itself is healthy.
Our Solution:
At TE Teras Tech, we perform Power Quality Analysis using high-resolution analyzers to capture THD-V, THD-I, unbalance, and transients in real-time. We identify the actual source — whether from the supply network, capacitor bank resonance, or nonlinear loads — and propose corrective actions such as harmonic filters or line reactors to stabilize your power system.

2. Thermal Overload or Ambient Influence

Root Cause: Fluctuating load demand, high ambient temperature, or poor ventilation inside motor enclosures.
Effect: Thermal overload relays respond to rising winding temperature and trip intermittently, especially during peak production hours.
Our Solution:
We conduct temperature profiling and thermal imaging to check winding and casing temperature rise. Our rewinding process uses Class H insulation and optimized slot-fill ratio to lower hotspot temperature. Combined with improved cooling path design, this prevents nuisance tripping caused by thermal overloads.

3. Insulation Leakage and Moisture Contamination

Root Cause: High humidity or condensation within terminal boxes and stator windings.
Effect: Gradual leakage current or momentary ground faults cause residual current devices (RCDs) or earth-fault relays to activate randomly.
Our Solution:
We use Motor Circuit Analysis (MCA) to evaluate insulation resistance, polarization index, and phase balance. Motors showing partial leakage are dried, re-varnished, and vacuum-impregnated for complete moisture removal — ensuring reliable insulation integrity under all operating conditions.

4. Bearing Current and VFD-Related Faults

Root Cause: PWM (Pulse-Width Modulated) switching from VFDs can induce shaft voltage, causing bearing fluting or transient discharges.
Effect: Ground-fault relays may sense these spikes as short circuits, resulting in irregular tripping events.
Our Solution:
Our technicians inspect for electrical discharge damage (EDD) and perform ultrasound friction analysis to detect early bearing degradation. We recommend insulated or hybrid bearings, shaft grounding rings, and proper cable shielding to eliminate VFD-related electrical stress.

5. Mechanical Imbalance and Rotor Eccentricity

Root Cause: Misalignment, bent shafts, or uneven air-gap due to improper installation or bearing wear.
Effect: Sudden vibration spikes alter current waveform symmetry, fooling protection systems into tripping under the impression of an electrical fault.
Our Solution:
We apply laser alignment and dynamic balancing down to micrometer precision. Our vibration diagnostics verify true mechanical stability, ensuring smooth torque transmission and protecting both bearings and winding from secondary stress.

Moving Toward Reliability and Zero-Failure Performance

Random tripping is rarely “random.” It’s usually a combination of small electrical and mechanical irregularities overlooked during conventional maintenance.
At TE Teras Tech, we combine electrical diagnostics, mechanical precision, and predictive analysis to pinpoint the true cause — turning hidden symptoms into clear, data-based solutions.

Why Choose TE Teras Tech

Since 2002, we’ve specialized in motor and alternator performance management, rewinding, and energy-efficiency optimization.
We go beyond repair — delivering measurable reliability through Motor Circuit Analysis, Power Quality Testing (IEC 60034-30-1 Compliance), and Predictive & Preventive Maintenance programs tailored to your plant’s needs.

Get in Touch

If your motor trips without warning or shows erratic shutdown behavior, don’t leave it to guesswork.
Let TE Teras Tech analyze and stabilize your system for uninterrupted operation.
Contact us today for professional diagnosis and consultation.

Common Electric Motor Failures — And How We Overcome Them

1. Overheating and Insulation Breakdown

Root Cause: Continuous overloading, poor ventilation, or unbalanced voltage supply often causes temperature to rise beyond insulation limits.
Effect: Insulation hardens and cracks, leading to short circuits or phase-to-phase faults.
Our Solution:
At TE Teras Tech, we perform Motor Circuit Analysis (MCA) to identify early insulation weakness before complete failure. During rewinding, we use Class H insulation systems with optimized slot-fill and air-gap balancing to ensure longer thermal endurance and lower temperature rise.

2. Bearing Failure

Root Cause: Misalignment, lack of lubrication, contamination, or electrical fluting from variable-frequency drives (VFDs).
Effect: High vibration, noise, and eventually rotor-stator contact.
Our Solution:
Our preventive maintenance includes ultrasound friction and vibration analysis to detect early bearing wear. We also apply laser alignment and precision balancing to eliminate mechanical stress, ensuring smooth and efficient rotation.

3. Rotor Bar or End-Ring Damage

Root Cause: Excessive starts, frequent torque surges, or improper rotor casting in older motors.
Effect: Torque pulsation, reduced efficiency, and unsteady current draw.
Our Solution:
We conduct Motor Current Signature Analysis (MCSA) to identify broken bars or eccentricity. Our workshop performs rotor bar re-casting or complete rotor replacement using balanced copper alloy designs that restore original torque capability and reduce stray losses.

4. Winding Short or Ground Fault

Root Cause: Moisture ingress, aging varnish, or poor rewinding practice.
Effect: Reduced insulation resistance and sudden tripping under load.
Our Solution:
We dry and re-varnish coils using impregnation process and perform Motor Circuit Analysis Electrical Test to verify reliability before delivery. Every rewound motor is supplied with a 12-Month Warranty, reflecting our confidence in workmanship quality.

5. Unbalanced Supply and Power Quality Issues

Root Cause: Harmonic distortion, voltage imbalance, or undersized cable connections.
Effect: Motor runs hot, power factor drops, and energy cost increases.
Our Solution:
Using our Power Quality Analyzer, we assess THD-V, THD-I, PF, and kWh consumption to identify inefficiencies. We help clients implement capacitor banks, harmonic filters, or energy-saving IE3 class motors to improve stability and reduce energy wastage.

6. Mechanical Wear and Rotor Eccentricity

Root Cause: Improper assembly, worn housings, or tight bearing fits.
Effect: Eccentric magnetic pull increases stray losses and vibration.
Our Solution:
Our skilled technicians re-machine bearing housings and perform dynamic balancing with micrometer accuracy. This ensures proper thermal expansion and minimal vibration, achieving Zero-Failure Performance in the long run.

Why Choose TE Teras Tech?

Since 2002, we have specialized in motor and alternator rewinding, repair, and performance management.
Unlike conventional repair shops, we transform maintenance into management — combining diagnostic analysis, energy-saving optimization, and predictive maintenance.
We work closely with global motor brands such as ABB, Brook Crompton, TECO, and Sumitomo as our collaborative associates, providing local technical support and performance enhancement solutions to their users.

Key Services:

  • Electric Motor Rewinding & Overhaul
  • Motor Circuit & Current Signature Analysis
  • Laser Alignment & Dynamic Balancing
  • Energy Efficiency Testing (Direct Method)
  • Predictive & Preventive Maintenance Consultation
  • Moving Toward a Sustainable Future

Malaysia’s industrial sector is moving toward High-Efficiency Motors (HEM) and energy-saving standards under MEPS 2027.
By repairing, rewinding, and optimizing existing motors, we help industries reduce downtime, save energy, and lower carbon footprint — aligning local engineering practice with the global sustainability movement.

Get in Touch

If your motor shows signs of vibration, high temperature, or poor performance, don’t wait for a total breakdown.
Let TE Teras Tech restore your equipment to its peak condition.
Contact us for professional consultation or inspection today.