Manual for VT Guard Pro

The VT Guard Pro is an advanced security device designed to protect MV inductive voltage transformers (VTs) against ferroresonant oscillations, particularly in open-delta connections of three single-phase VTs. It actively dampens these oscillations, preventing damage from overcurrents and overvoltages, without consuming excessive power during normal operation. Two versions exist: VT Guard Pro and VT Guard Pro-D, the latter featuring self-diagnostic capabilities. The device is installed in a low-voltage compartment on a DIN rail and connected to the VT's measuring windings. Settings for threshold voltage and time delay can be adjusted using jumpers. The VT Guard Pro-D also includes diagnostic connections and status LEDs. Proper installation involves disconnecting power and using appropriate isolators. Regular maintenance focuses on keeping air-ventilation gaps clean.