Voltage(V) & Miliamp(mA) Outputs

Three Wire output or 3-wire transmitters have one power supply terminal in common with the output signal.

• These transmitters can support zero based output signals
• As the power is supplied separately output drive and produce auxiliary outputs to support input sensors such as load-cells are possible.
• Three wire transmitters are available with and without Input to output isolation.

Separately Powered or 4-wire transmitters are transmitters, isolators or converters requiring a separate power supply to operate.

The input signal is converted or isolated and re-powered to give a high-drive output signal. The transmitter becomes the source for the process signal.

• The fully isolated supply has no galvanic connection between input and output. Most APCS products have a fully isolated supply on auxiliary powered units.
• The Partially isolated supply will have some connection between input output or both. The APCS power drivers - PD121 and PD122 require a separate power supply to provide the necessary isolation path.

Only an isolator that provides true 3-way galvanic isolation will isolate all three paths supply, input and output.

The 0-5V output signal is derived from the measured variable. This represents a load on the measured signal. In the case of a high current CT this load is minimual.