Condition monitoring

EA Technology has launched a combined ultrasonic and transient earth voltage (TEV) detector that is capable of detecting both surface and internal discharges in electricity switchgear.

The UltraTEV hand-held instrument combines ultrasonic sensors to pick up early signs of surface discharge, with transient earth voltage (TEV) sensors to detect internal discharges.

A significant number of switchgear ‘in service’ failures are due to insulation breakdown preceded by increasing levels of partial discharge activity. Early detection of these discharges allows remedial action to be undertaken, preventing catastrophic failure.

The UltraTEV features two indicator lights, Ultrasonic activity and TEV activity. The TEV indicator shows green for ‘OK’, amber for ‘warrants checking more frequently’, and red for ‘requires immediate investigation using more sophisticated instruments’.

The key to the UltraTEV’s accuracy is the threshold levels to which the condition indicators have been set. These have been derived from measurements of partial discharge taken in 6,000 substations and involving nearly 50, 000 switches. They are stored in a database, which has been built up by EA Technology over more than 37 years’ working with the electricity industry.

EA Technology developed the UltraTEV with input from the members of the Partial Discharge User Group, a forum representing 90% of UK Electricity Network Operators.

The size of a television remote control, UltraTEV units are supplied with rechargeable batteries and feature a simple on/off switch.

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