APCS the Signal Conditioning Specialists

Find a Product Output ⇒ Function ⇒ Input

Select products by Output then Input and then Function. The number of wires (e.g. 2-Wire) listed refers to the number of connections to power the Transmitter and connect the output.

dc Input Products

4-20mA 2-Wire Output

Loop powered or 2-wire transmitter

Loop powered or 2-wire transmitter

Loop powered or 2-Wire transmitters are connected in series with all instruments driven by the same signal or current loop.

Loop powered transmitters must have a live zero output signal (4mA) as the power to operate the transmitter is taken from the output signal. This is achieved by tolerating a voltage drop of up to 12V across the output of the transmitter.

  • The obvious advantage of loop powered transmitter lies in the reduction of cabling and installation costs.
  • Loop powered transmitters are available with and without Input to output isolation.
 

dc mA/V 3-Wire Output

Loop powered or 2-wire transmitter

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.

4-20mA 4-Wire Output

Separately Powered or 4-wire transmitter

Separately Powered or 4-wire transmitter

Four wire output transmitters have two wires the power the isolator / transmitter and two wires tho connect the output signal. The energy to drive the 4-20mA output signal comes from the separate power wires. Please refer to section dc mA/V 4-Wire Output for further details of 4-Wire transmitters.

 

dc mA/V 4-Wire Output

Separately Powered or 4-wire transmitter

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.