TOV Temporary Overvoltage Test System

The HVEX Temporary Overvoltage (TOV) Test System evaluates single-phase or three-phase low-voltage surge protective devices (SPDs) under temporary overvoltage conditions specified for those devices. The documented configuration includes a 12.5 kVA three-phase supply transformer and a TOV transformer with a 1200 V secondary and a 5 kVA rating. These values describe the test system, rather than the nominal voltage of the SPD’s power system. Applied levels, duration, and current conditions must be selected for the specimen, circuit, and test procedure. Applications include development and verification of low-voltage SPDs by manufacturers and laboratories. Procedure selection considers the relevant TOV requirements of the IEC 61643 family and the applicable edition, including IEC 61643-11 and the common requirements of IEC 61643-01 for SPDs connected to AC low-voltage systems. The TOV test is one part of SPD evaluation and does not by itself establish full product certification. The supplied configuration can be specified for the SPD and laboratory workflow, with operator training and HVEX technical support.