Wednesday, April 17, 2019

What is Spot Vs. Area Temperature Measurements as part of an Electrical Maintenance Inspection?

In today’s business world, it is mission critical that a company introduce programs and procedures that will identify faults or deviations in critical electrical assets before the asset fails.  Electrical asset failures can lead to lengthy unscheduled downtime and potential loss of revenue for the company, not to mention costly repairs. Is it possible to identify an asset that is deteriorating and arrange to fix it before it fails? YES, it’s called Condition Based Maintenance.

Electrical equipment requires periodic maintenance to maintain normal operations. These inspections must often be performed on the assets operating under full load conditions. The inspections require direct access or direct line of sight to the energized components inside the electrical system. Traditionally, these inspections were time-intensive and required access panels and doors to be opened which can be extremely dangerous to the personnel performing the inspection task. The inherent safety risk as well as time and cost requirements needed to perform these inspections often led management to push out or cancel a maintenance inspection schedule which could lead to catastrophic asset failures causing downtime and, sometimes severe injury or loss of life.

Innovative technologies called Electrical Maintenance Safety Devices [EMSDs] have emerged that improve the efficiency of electrical inspections. EMSDs maintain an energized compartment’s closed and guarded condition during the inspection process thereby reducing the time needed to complete the inspection and ensuring that the inspectors are not put at risk.

EMSDs exist to facilitate the most common inspection type – infrared thermography. Part of an electrical inspection may include temperature measurements using an infrared window and infrared camera. There are several measurement settings on the Infrared Camera that the thermographer can select: two settings are SPOT and AREA MAXIMUM.

                                                                                                         Spot Vs. Area Temperature Measurements

SPOT Temperature Measurements

A SPOT temperature measurement will show a temperature of a single point to which the camera is aimed. The problem with using the SPOT setting is it only measures the temperature of one single point. Unless the thermographer continuously moves and aims the camera around the entire area of the panel, he may not see a particular temperature that is suspect or outside of specification. A SPOT measurement is useful when trying to compare the temperature of one item to another or when trying to correlate one component to another.

AREA Temperature Measurements

When the infrared camera is set on the AREA MAXIMUM temperature measurement, it provides the maximum temperature across the entire area within the area square on the camera screen. This setting provides the thermographer with more information and more accurate temperature readings inside the entire panel. As a result, he is less likely to miss a hot spot 11 is recommended to select the AREA MAXIMUM temperature setting on the infrared camera when performing electrical inspections.

Thorough understanding of the difference between SPOT and AREA temperatures allows the thermographer to assess the health of energized electrical components safely and routinely.


EMSDs allow for more frequent inspections leading to the creation of asset health history files and the capability of performing data trend analysis on the assets. Temperature trending using infrared thermography is one type of electrical inspection that allows the maintenance team to monitor the health of energized electrical assets.



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