Condition Monitoring Services

According to research, sudden power outage in a single datacenter can cost up to $10.00 every minute! The US Department of Energy estimated that outages cost the US economy $200 billion per year. With so much at risk, it is no longer acceptable to rely solely on visual inspection of critical machinery but to employ condition monitoring solutions to augment the human inspector.

ON Engineers specializes in the condition monitoring and machine health assessment of electrical equipment and systems including switchgears, transformers, cables and electric motors. Examples of electrical condition monitoring range from basic ultrasonic scanning (most commonly used method) to the use of high-frequency partial discharge sensing/sampling that enable accurate developing fault detection. The data analysis enables clients to prevent unexpected production downtime while implementing condition-based maintenance (also known as preventive maintenance or predictive maintenance program) for their electrical assets.

Our condition monitoring techniques and services are sought after in particular by mission-critical installations such as datacenters or even upscale hotels. We have many success cases of early detection and fault prediction that helped clients mitigate unplanned failure and avoid reactive maintenance that overrun maintenance costs.

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Special Considerations in Condition Monitoring of Electrical Equipment

For rotating equipment or rotating machinery, mechanical condition monitoring mainly involves vibration monitoring and vibration analysis. Excessive vibration generally leads to machine failure. Detecting and trending vibration data forms the basis of predictive maintenance for such rotating assets. Today's vibration monitoring techniques have advanced to the point where in-depth vibration analysis and vibration data collected can provide additional information on the type of fault, e.g., if the fault is due to looseness, to the shaft bending, to defective bearings or other causes that help pinpoint the problem and possible solutions.

Condition monitoring of electrical equipment is generally tougher to perform. Not only are most of the equipment static in nature (i.e., there are no continuously moving or rotating parts), the faults are partial electrical discharges that develop at much higher frequencies easily drowned out by environmental noise.

As an electrical engineering firm responsible for thousands of client electrical installations, ON Engineers have focused our research and development in this area. We constantly field-test the latest OEM condition monitoring systems, invest in best-in-class tools, sensors, electronics, data processing and software development. Today, electrical condition monitoring has reached similar levels of sophistication as mechanical condition monitoring, i.e., through advanced data acquisition and analysis of the fault patterns, we can also provide additional information on the fault beyond its detection, including its direction and location with a high degree of confidence.

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Online Condition Monitoring and IOT

IOT, the Internet of Things, is the concept that equipment can be hooked up to different kinds of sensors connected to the internet to form an online condition monitoring system. This raises the expectation for such online condition monitoring systems and IOT enabled permanent monitoring installations.

In electrical terms however, 'online' also means "the power is 'on'", and 'online condition monitoring' refers to the monitoring of the equipment whilst it is energized, i.e., without the need to power or shut down. It means performing the condition monitoring measurements while the equipment is 'live' without disruption to production or operations.

In fact, today's most advanced 'online' condition monitoring technology places sensors literally 'on the line', i.e., as close to the live cables as possible. Such advanced techniques are more labor intensive but offer far more detail than the rudimentary switch room or exterior cabinet surface scanning services.

On the IOT front, today's cost-effective sensors are quite rudimentary and not near the sophistication that electrical machine condition monitoring techniques require. These first level condition monitoring sensors, while providing continuous monitoring, are capable of alarm level detection with high thresholds and are employed by some predictive maintenance engineers as first-line defense in their predictive maintenance programme.

While it is costly to retrofit IOT-based monitoring solutions in existing equipment due mainly to (lack of) asset access possibilities, in the near future, equipment such as switchgears and transformers will be designed and manufactured with embedded sensors that have better proximities to the live components and are internet connectable to enable remote monitoring.

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ON Engineers' condition monitoring value-added and differentiation

Depending on each client's business objective and budget, our condition monitoring solutions and services are flexible, fully customizable and not confined to any single OEM catalogue. While it may not be cost-effective to fully implement IOT enabled permanent monitoring solutions, we have benefitted many clients with our innovative hybrid, best of breed approach. For one client, we embedded IOT-like sensors and monitoring system but opted to log the data on-site. For another client, we provided monthly on-site inspections with flexible use of multiple sensors. To us and our best preventive maintenance clients, condition monitoring is a journey and a partnership that is always innovating and fresh.

As electrical condition monitoring becomes more widespread, and from our vast experience and case studies, we discover that most faults are found in weak links in the electrical installation and less frequently within a major piece of OEM equipment (e.g., switchgear) per se. Our system wide approach to condition monitoring does not limit the investigation to major components but we look at the entire installation from cables to joints to other accessories that are customized for the particular site. It is in the interest of the asset owner to apply this holistic approach to condition monitoring because the system is only as strong as its weakest link, regardless of how good the main components are.​

Best Practices in Electrical Condition Based Monitoring​

​Infrared Thermographic Scanning

Infrared Thermography is an advanced form of temperature monitoring that measures the surface temperature of objects and gives fast and valuable answers to questions about the operating condition without requiring a shutdown. It is a non-contact means of identifying electrical components that are warmer than they should be – often an indication of areas of impending power failure.​

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Dissolved Gas Analysis (DGA) and Oil Analysis of Oil-Insulated Transformer​

Dissolved Gas Analysis is a condition monitoring technique applicable to oil-insulated transformers. The oil analysis shows the chemical composition of the oil sample and in particular any trace of dissolved gases that are present in the sample. If there is a defect in the transformer coil that is immersed in oil, e.g., a partial discharge (PD) or high temperature spot, it could leave a chemical trace in the form of a gas that is dissolved in the oil.

Traditionally, DGA can only be performed off-site in a laboratory. With progress, ON has developed mobile DGA analysis capability that enables on-site sampling and results. This is extremely useful in case of an emergency where time is of the essence.

Besides DGA, with the chemical composition report of the oil sample collected from an on-site transformer, we are able to evaluate the quality of the transformer oil with additional parameters such as moisture and di-electric strength. Periodic or even permanent oil quality monitoring enables clients to trend and foresee the rate of oil quality aging, and thus allows planning for the next replacement.

Read ON's in-house specialist guide on Dissolved Gas Analysis here.  

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Responsibilities of an excellent Condition Monitoring System are to:

  • Identify and apply a best-of-breed combination of measurements applicable to various components of the system, i.e., infrared thermography, partial discharge detection via ultrasound and other high frequency signal sampling, dissolved gas analysis and oil analysis where applicable to...
  • Detect incipient faults as early as possible so as to predict possible problems.
  • Demonstrate cause-symptom-effect relationships to pinpoint the need for corrective actions.
  • Assist in the timing and planning of scheduled repairs and maintenance.
  • Rectify defects in order to prevent equipment deterioration.
  • Follow-up with an appropriate maintenance programme
  • Reduce downtime by avoiding unplanned shutdown.
  • Carry out condition-based monitoring with no power interruption to the premises.
  • Achieve minimum maintenance costs.


Our Condition Monitoring Systems and Predictive Maintenance Services include:

  • Level-1 IOT embedded sensors systems
  • Dissolved Gas Analysis and Transformer Oil Analysis
  • Ground Grid Measurement
  • Infrared Thermography
  • Online and Offline Partial Discharge measurement
  • RFI Measurement
  • SF6 Gas Measurement
  • Smoke Particle Measurement
  • Ultrasonic Measurement

Technical Papers written by ON Engineers

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