Sightglasses allow safe infra-red inspection

CTI Cyclops infra-red sightglasses and ports allow infra-red surveys of electrical equipment to take place without the need to expose the thermographer to the risks of electrical discharges.

Infra-red thermography has come a long way since the "portable" thermal imaging systems of the late 1970s.

Today's latest thermal imaging systems are little larger than a camcorder and have the ability to store thousands of high quality, radiometric images onto storage media little larger than a credit card.

However, for all the marvellous technological advances that have taken place over the past 20 years, for the electrical thermographer a major problem still remains: infra-red cameras cannot see though electrical panels.

This problem is not down to the cameras themselves, but to the physics of infra-red radiation.

Put simply, radiated heat - which is registered by the infra-red camera - cannot pass through metal, glass or plastic in sufficient quantities for the camera to detect and build a picture for us to see.

In cases such as glass or plastic, even though our eyes may see through it, does not necessarily mean that an infra-red camera can.

As such when surveying electrical equipment, a direct path to the target object is required with the target object energised and under load.

Traditionally, there were two solutions to this problem.

The infra-red survey was carried out without removing the covers.

This simply does not work.

The front face of the switchgear may indicate a raised temperature but the temperature does not necessarily indicate a fault condition.

Even if a fault is causing the temperature increase on the panel front, there is insufficient information available from the thermogram to specify what the fault actually is.

Alternatively, the covers were removed.

This method provides the thermographer with the required direct path to the target which results in a clear thermogram for easy analysis and accurate fault detection and recognition.

However, there are problems with this method.

Switchgear manufacturers are aware of the dangers of exposing live electrical equipment.

As such interlocks are installed at manufacture on many pieces of switchgear to prevent unauthorised opening of doors while the equipment is live.

In these cases the doors cannot be opened without the interlock operating and de-energising the compartment, thus reducing the power source which will cause the fault to generate heat which may be detected by the camera.

Unfortunately, some door interlocks can be defeated and bolted covers can be removed.

When doing so, the thermographer is exposed to the live electrical equipment with no protection.

It must not be forgotten that a thermographer is not necessarily electrically minded or experienced and by exposing the equipment in this manner increases the risk of electrocution immeasurably.

Further by removing the covers unusual airflow is introduced into the equipment, this airflow can cause dust and other electrically conductive particles to travel around the enclosure, this is one of the most common causes of electric arc flashing.

This fault occurrence results in a localised explosion with temperatures reaching up to 20,000C - compared with the 5000C on surface of the sun - the associated blast wave can cause fatal burns at distances of 3m.

The massive overpressure caused by this blast can rupture eardrums and collapse lungs.

Until recently there was no safe, effective means of carrying out thermographic surveys of electrical equipment.

In the 1990s the CTI cyclops infra-red sightglasses were introduced into the market in an attempt to rectify this problem.

The CTI Cyclops infra-red sightglasses and ports allow infra-red surveys of electrical equipment to take place without the need to expose the thermographer to the risks and problems detailed above.

The CTI Cyclops units are permanently attached to the switchgear in strategic locations to give the thermographer the best view inside of the equipment.

CTI Cyclops are made from specialist materials which allow infra-red radiation to pass through them and onto the infra-red camera making good quality thermograms possible, enabling the thermographer to resolve a fault quickly and accurately without ever opening the equipment.

Infra-red sightglasses and ports are available in many types and sizes which when combined provide the thermographer with the best commercially viable solution to electrical thermography.

In today's cost conscious world, the problem of using infra-red thermography to locate faults on covered electrical equipment is only going to get greater.

The development of infra-red sightglasses, ports and other innovative ideas is a welcome step forward in the pursuit of increased operator safety in conjunction with efficiency.

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