Our doctors will recommend that we have a blood sample to help identify a range of illnesses in order to diagnose problems within the body.

Oil filled switchgear can similarly be tested to allow diagnosis of early problems within a transformer for example. Oil samples can be drawn from the transformer, providing suitable valves are fitted without the need for a planned power outage. Transformers are expensive items that businesses depend heavily upon for production and a failure of such an item could prove catastrophic for production involving a long period of down time whilst a replacement item is sourced and installed.

The cost of oil analysis is inexpensive compared to a transformer failure and should be considered as a vital regular part of a maintenance programme and hence complying with the Electricity at Work Regulations. A routine analysis can indicate problems with the oil or transformer and our maintenance team here at MPN will be able to advise on corrective measures if needed. A routine analysis can include the following tests:

• Acidity – oil disintegrates with age and this test can indicate when the oil needs replacing.
• Water – oil, water and electricity don’t mix too well, so an early indication is critical.
• Electric strength – the presence of water, fibres and other contaminants greatly reduces the insulating quality of the oil.
• Colour – to the trained eye, this gives an overall condition of the oil.
• Appearance – visual contaminants may be present.
• Odour – an acrid smell may indicate presence of hydrocarbons.
• Fibres – fibres within oils can seriously reduce the insulating capability of the oil.
• Dissolved Gas Analysis – component parts of the transformer may breakdown and give off certain gases as a result. This test can determine which area of the transformer is degrading.
• Polychlorinated Biphenyl (PCB) – Banned in the 1980’s due to environmental and health concerns, PCB’s were often used in the construction and use of transformers etc. A high level of PCB would involve a specialist disposal process.

MPN has vast experience in all items of High Voltage electrical maintenance and will be pleased to offer advice and guidance on the merits of a maintenance contract for your high voltage connected equipment.

Contaminated Oil Sample

This recent oil sample from a transformer shows what appear at first to be bubbles. They are in fact droplets of water!