4-wire AC Data Plug-in Isolator Card

The 4-wire AC Data Plug-in Isolator Card provides high voltage isolation between an incoming dedicated four-wire AC data line and a data transmitting/receiving device located in the substation.

Product Number CLEI Code Description Download Documents
7501-24 NPPMC401AA 4-wire AC Data Plug-in Isolator Card Specifications Installation Guide


  • Dedicated line modems
  • Supervisory control and data acquisition (SCADA) systems
  • Teleprotection
  • Tone relay control systems
  • Analog carrier systems
  • Any other equipment using tone related signalling
  • Digital data service (56 or 64 kbit/sec)


  • The card is suitable for transmission of frequencies up to 200 kHz (56 kB) provided the data line is conditioned for operation at this speed
  • The card does not require power input from either the Central Office (CO) or the Teleline shelf
  • The card permits the flow of CO simplex sealing current from one pair to another. Simplex sealing current is not transmitted across the isolation gap to the Station side

The 4-wire AC Data Plug-in Isolator Card can be housed in the 3-card Shelf (751127), the 5-card Shelf (751112/15), the 8-card Shelf (751109/15), or in many of our High Voltage Interface (HVI) pre-configured units.


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