ADVANTAGES:

  • Greater voltage availability for both transmitter and load
  • Short circuit protection on the transmitter power supply

DISADVANTAGES:

  • Need of an infallible equipotential ground system as for standard passive barriers
  • Need of ground isolated hazardous location devices
  • Higher cost than passive barriers

The most used and important of this types of barriers is the current repeater used to interface hazardous location transmitters with un-certified instrumentation located in safe area.

Circuit wise it is similar to a transmitter passive barrier on which safe area side a shunt, with a current repeater amplifier that arrogates the duplicate of the transmitter current on the safe area output circuit, is present.

They are particularly needed in those applications where the supply voltage, deduct the drops on the standard passive barriers, is not sufficient to supply the transmitter and provide an usable voltage to the safe area load.