The Transient Voltage Surge Suppressor or TVSS has been designed as part of a co-ordinated approach, to prevent damage to electrical installations by absorbing transient overvoltages at the main incoming distribution panel.

The TVSS should not be confused with voltage stabilising transformers intended to hold the power supply voltage within predetermined levels for a given load.

The TVSS provides protection from voltage spikes that can occur between phases to neutral thus providing protection in all possible modes. Protection is achieved by matching high energy absorbing elements.

The TVSS is fitted with two stages of protection which are programmed to ensure that if the first stage ceases to function, the second stage gives the continuity of protection until a replacement DSP is fitted. The protection status of the DSP is indicated by a system of neon indicators as follows: