Contents

Overview

Other IR Applications

Sample IR Images:
  1. 240 KVA Transformer
  2. Substation
  3. Vault Connections
  4. Heat Trace Transformer
  5. Transformer Oil Level
  6. Transformer Fins
  7. Gantry Crane Bus

Overview


Two important elements facing a thermographer performing outdoor electrical inspections are environmental factors and safety.

Wind and sun will drastically reduce the effectiveness of an IR survey. Wind is heat transfer by convection, and it doesn't take much of it to remove a serious thermal signature completely. The sun causes two problems. It will thermally load all of the components, removing temperature differences. It will also cause serious reflections, especially for shortwave cameras.

The best way around environmental problems is to avoid them completely. A calm evening or morning when the sun is not shining on the equipment is ideal, especially if it corresponds with high loads on the equipment. If this is not possible, it is vital to understand the effects that the environment will have on your results.

The high levels of energy in much outdoor electrical equipment increases the danger level when inspecting them. Two simple practises will go a long way to reduce the risk of serious injury or death. As part of the hazard identification which must be completed before any work is done, use your infrared equipment to look for hot spots before entering substations or approaching electrical equipment, not just overhead, but all around. You have a unique tool for seeing critical problems that are invisible to the naked eye.

Another very effective means of keeping the thermographer safe is the buddy system. Looking through an eyepiece or at an LCD monitor at the world around you can create tunnel vision. A thermographer may temporarily lose track of the physical dangers such as tripping hazards. Also, it is very difficult to perform CPR or First Aid on yourself in the event of a serious accident.

The high voltages involved in outdoor electrical equipment demand that we treat both the inspection procedure and the safety aspects with respect.

1. 240 KVA Transformer
This image shows approximately half of the North side cooling fins/tubes to be exceptionally cool, indicating possible plugged tubes (right-hand side of image). The image is from an East elevation showing both sides of the transformer.
You may left-click on the picture for an expanded view.
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2. Substation

 The outdoor electrical equipment providing power to your facilities are often overlooked or ignored during surveys performed by inexperienced technicians. Maverick's standard electrical surveying practice is to inspect these support systems while on site to ensure their continued dependibility. This image shows a loose pot head connection on the center phase at a substation. Unattended, this problem could lead to a loss of power or fire.
You may left-click on the picture for an expanded view.
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3. Vault Connections
Hot connections in underground distribution vaults are readily apparent with infrared technology. Fortunately, enviromental factors are usually not an issue, although one must be careful that the sun is not shining on components from doors or grating. The load on the line, the rating of the component, and the temperature rise must all be taken into account when determining the criticality of the fault.
You may left-click on the picture for an expanded view.
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4. Heat Trace Transformer
All four cells are under a load of 81A - 84A. However, there is a 31V drop in output from circuit A to circuit B, likely due to the failure of cell 1 (far right). This is an example of a "hot spot" being the symptom while a cool area is the actual problem.
You may left-click on the picture for an expanded view.
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5. Transformer Oil Level
The oil level in this transformer (see the black line) is detectable, however the temperature differences are less than 1° C, so fine adjustments of the level and span are necessary. The areas of solid white in the image are due to the sun shining on the open door and building wall.
You may left-click on the picture for an expanded view.
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6. Transformer Fins
This image shows a portion of the cooling fins on a chemical facility power substation transformer. The fins appear to have poor oil circulation, probably due to pluggage or a low oil level.
You may left-click on the picture for an expanded view.
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7. Gantry Crane Bus
This is a connection on the bus bars for a trolley house on a large gantry crane. Under partial load, the poor connection is apparent as heat transfers through the plastic covering.
You may left-click on the picture for an expanded view.
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