The EGP-3(6)DF Series voltage transformers, designed for indoor applications, are three-phase “grounding potential transformers” (GPT), or “grounding voltage transformers” (GVT). On the primary side, each phase of the voltage transformer, or potential transformer, comes with a fuse to protect against overload and short circuit currents. This type of voltage transformer features coils insulated with Araldite® epoxy resin, as well as a five-legged laminated core. The primary rated voltage is 3300V (Y connection) or 6600V (Y connection). When the VT, or PT, is used in conjunction with measuring or monitoring instruments, the secondary rated voltage is 110V (Y connection).

This voltage transformer can also be used as a grounding voltage transformer for ground-fault protection. When any one phase of the primary side is grounded in an abnormal or accidental situation, the tertiary rated voltage is 0~190V (open-delta connection) or 0~110V (open-delta connection). The tertiary side produces and transmits a ground fault voltage signal to a monitoring device or ground relay, by which the VT (PT) achieves its monitoring purpose and the protection of equipment or individuals.