The 4D200 is specifically designed for operation with the RMS type 2V200 TPI to frequency transducer. The 2V200 provides a noise immune interface between the tap changer & the 4D200 via a 0 to 5KHZ frequency signal.

Alternatively the 4D200 may be configured to accept a BCD coded input direct from the tap changer or via a voltage to BCD transducer. Where an RMS 2V164 Voltage Regulating Relay is being used with a 2V200 TPI Transducer, a 4D200 may be connected in parallel to provide a local easy to read tap position indication.