01296 434 808 info@indss.co.uk


Follow these links for legislative details and information about your legal duties and responsibilities for ALL HV & LV Electrical Equipment

Testing for Partial Discharge

The Engineer in this video is undertaking non-intrusive detection of partial discharge activity on high voltage (HV) electrical equipment using our UltraTEV pickup probe.

The UltraTEV is intended to quickly detect the presence of discharge activity and give an indication if further investigation is needed through detection of both ultra-sonic and electromagnetic activity.

When partial discharge occurs it can either be detected by ultra sound sensing or by placing the instrument on the switchgear to detect transient earth voltages within the outer metal cladding of the switchgear. Partial discharges are electric charges that do not completely bridge the phase electrodes.

The magnitude of such discharges is usually small, however, they do cause progressive deterioration of insulation that may lead to eventual failure within the switchgear. The red light indicator lighting up on the UltraTEV in the video is proving the presence of partial discharge within the HV equipment.

Transformer Maintenance

One common cause of localised power loss is a transformer failure. The good news is adequate maintenance can prevent this loss.

With liquid-filled transformers, these typically receive some partial maintenance perhaps in the form of oil sampling or temperature monitoring. Unfortunately, the air cooled transformers are not usually maintained at all. These air cooled transformers should be maintained annually by a specialist contactor who will carry out transformer enclosure internal inspections.

With either type of transformer, the typical maintenance in industry is grossly inadequate. Loss of power isn’t the only potential consequence of inadequate transformer maintenance. A transformer failure can result in loss of human life and catastrophic loss of the facility.

Have you evaluated your transformer maintenance program lately? Contact INDSS Ltd today for a free consultation of your Transformer, HV Equipment and LV Equipment.


Effective Transformer Maintenance Planning

Your first step in forming an effective transformer maintenance plan (or evaluating the one you have) is to determine how critical each transformer is (e.g., on a scale of 1 to 5).

This allows you to allocate your limited maintenance resources. Transformer failure risk factors vary by the operating environment, so your next step is to carefully assess the environment of each transformer for issues such as heat, contaminants, power quality, load distribution, and access for maintainability. For each of these, assign a severity rating.

Your budget is limited, so you must make decisions that balance cost against loss. This means you gear your program to control the most severe risk factors for the most critical transformers. What’s left over can be allocated to the next level of criticality.

Transformer Maintenance

What Is Transformer Maintenance?

Transformer maintenance consists mostly of testing, although it includes other activities (e.g., housekeeping-related). The three categories of transformer testing are:

Commissioning. Normally, you perform commissioning tests following initial installation. The test results provide baseline maintenance data. But if a transformer has not operated for a period of time, it requires re-commissioning.

Routine. These are data collection activities, such as recording temperatures and taking oil samples. This level of maintenance doesn’t usually require de-energisation.

Periodic. The complete menu of these tests requires a deep skill set, and thus must be undertaken by a specialist company such as INDSS Ltd. Please refer to our services page on our website for more details about this type of maintenance.

Transformer Maintenance

INDSS Ltd are one of the UK’s leading independent substation contractors
specialising in high voltage engineering


Independent Substation Services Ltd

Unit 31 Edison Road,
Rabans Lane,
HP19 8TE.

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01296 434 808