Can Infrared Inspection Windows Be Used on Transformers?

An electrical transformer is a device that converts electricity from one potential to another by changing voltage levels. Transformers improve the safety and efficiency of power systems by raising or lowering voltage levels as needed.  In the commercial and industrial environments, they are used in the distribution and regulation of power across long distances. Transformer failures lead to power outages and, depending on what is consuming the power, determines how widespread and how critical the outage will be.  Can transformers be monitored to identify faults before an actual failure occurs?  The answer is YES!

Electrical transformer failures are either mechanical or electrical in nature.  The common causes of transformer failures are poor craftsmanship, overload, line surges, connection deterioration, insulation deterioration (partial discharge), ingress of moisture or critters and sabotage.  Anything that causes the transformer to become hot will result in breakdown of the insulation causing it to become brittle over time eventually leading to a failure.

Maintenance Inspection Windows on Transformers

Condition based maintenance is key to avoiding a transformer failure and unplanned power interruption. A preventive maintenance schedule on transformers also facilitates replacement and budget planning for the company.  Technologies exist today that allow the maintenance team to detect early warning signs of failure.  These technologies include:

  1. Infrared Thermography – detects loose connections, crimps and cable creepage
  2. Structure Borne Ultrasound – detects loose windings and other mechanical faults
  3. Airborne Ultrasound – detects arcing, tracking and corona
  4. Transient Earth Voltage Detection – detects Partial Discharge events that are occurring inside of insulating materials
  5. Visual Inspection – while not a technology, visual inspection cannot be ignored. Visual inspections help find contaminates, moisture, water and pests such as snakes or rodents.
  6. Oil Analysis – on oil filled transformers, an oil analysis can detect degradation, leaks and insulation breakdown

Another consideration for transformer maintenance is personnel safety.  Many of these inspections require that the transformer be energized and operating under normal load conditions.  Tradition inspection processes required personnel to wear Personal Protective Equipment to perform the inspection of the energized transformer resulting in elevated risk of an arc flash or electrocution accident.

Fortunately, innovative products are available today that “Substitute” for traditional CBM methods by enabling the team to perform inspections on energized equipment under full load in a safe and guarded condition without having to wear PPE.  These products are known as Electrical Maintenance Safety Devices (EMSDs).  EMSDs make the inspection process easy and safe to perform.  Companies adopting EMSDs and condition based maintenance strategies assess the criticality of their assets and will schedule frequent inspections on those assets that are deemed most critical.  The goal is to find “it” and fix “it” before “it” fails by collecting and trending data over time to detect signs of gradual deterioration.   This strategy makes condition based maintenance cost effective and safer for the company as a whole.


EMSDs make routine inspections of transformers easier and safer to perform.  A condition based maintenance strategy collects and trends inspection data over time allowing the maintenance team to assess and monitor the health of transformers. Fixing a problem before acute failure occurs saves a company time, money and more importantly, eliminates power outages to the end user customer.

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