Light touch: Predictive maintenance for electrical systems: Part 1

Build the right combination of predictive tools and technologies to proactively monitor your electrical systems.

By Sheila Kennedy, contributing editor

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The potentially catastrophic consequences of electrical system failures and hazards must be avoided at all costs. Regular predictive maintenance (PdM) on electrical systems lets maintenance teams detect and correct problems before they can shut down equipment or production lines or cause a safety incident.

Whether conducted in-house or outsourced to reliability specialists, PdM inspections – followed up with timely, precise repairs – can protect against electrical accidents and save companies millions of dollars by reducing unscheduled downtime, lowering equipment maintenance costs, and extending the useful life of machinery.

Is your electrical PdM program up to snuff? Here, check out some of the newest electrical PdM tools and applications as well as popular testing options and practical PdM recommendations from industry pros.

Effective tools and technologies

Wide-ranging options exist for online/energized and offline testing of electrical systems. Tom Bishop, senior technical support specialist at the Electrical Apparatus Service Association (EASA), notes that there's a wide scope of available inspection types with these common motor tests:

Offline tests for motors

  • Insulation resistance tests
  • Polarization index tests
  • Motor electrical circuit parameters evaluation (resistance, inductance and capacitance)
  • Rotor influence tests to check for open rotor bars

Online tests for motors

  • Measuring line voltages and currents
  • Motor current signature analysis
  • Vibration analysis for electrically induced frequencies
  • Thermography
  • Ultrasonic inspection

Technology has come a long way in the past 30 years, remarks John Bernet, mechanical application and product specialist at Fluke Industrial Group. “There are now easy-to-use tools available for operators to screen components of electrical systems for potential problems," Bernet says. "Technicians can then troubleshoot the problem to find the specific fault and recommend a correction and then use the same screening tools to verify that the fault has been corrected and quickly get the machine back into service.”

The emergence of the internet of things (IoT) is extending the value of PdM. “By collecting data through connected maintenance technologies, personnel can better evaluate the asset’s utilization, environment, lifecycle and performance,” says Emanuel Kourounis, services business development manager at Schneider Electric. “This data also enables a more condition-based maintenance approach to help companies allocate limited resources in managing their op-ex and cap-ex budgets along with maximizing their general maintenance activities.”

Thermal imaging

One of the most effective PdM technologies for operating electrical systems is infrared (IR) thermography, says R. James Seffrin, director of the Infraspection Institute. “A thermal imager converts the normally invisible infrared radiation emitted by an object into a monochrome or multicolor image that is representative of the thermal patterns across the surface of the imaged object." Many thermal imagers also can provide temperatures of imaged objects, he notes.

Infrared inspections are conducted while the electrical system is energized and under load. Typical defects that may be found include loose/deteriorated connections, overloaded circuits, unbalanced loads, and defective equipment, Seffrin says.

Predictive IR technologies can be employed to mitigate the potential for human error in monitoring and maintaining assets, notes Schneider Electric’s Kourounis. “Asset-specific algorithms, thresholds, and rules can be used to detect thermal abnormalities in the performance of the monitored assets, which can then be further analyzed by industry experts to validate the findings and develop a list of recommended next steps,” he says.

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