The CTRCT-1 and CTRCT-2 regulator boards are current trip regulators with current transformer (CT) feedback. Both boards provide current regulation in ac controller configurations with a latching overcurrent trip that may be configured for automatic or manual reset. The CTRCT-2 provides enhanced functionality with optional voltage regulation, potentiometer adjustable ramp time, transistorized status signals indicating overcurrent , current limit, and trip reset.

The CTRCT-1 and CTRCT-2 boards utilize current feedback from CTs on the single-phase or three-phase mains. A diode rectifier and burden resistor generates the current feedback signal required for the regulator circuit.


  • Isolated Current Transformer Feedback
  • Automatic Crossover
  • Current Trip with Automatic or Manual Reset
  • Optional Voltage Regulation (CTRCT2 Only)
  • Soft-Start and Soft-Stop
  • For Single-Phase and 3-Phase Systems



The CTRCT-1 AND CTRCT-2 includes the following features:

  • Feedback Signal Isolation: Current transformers provide galvanic isolation between the regulator circuit and the ac mains. The CTRCT-2 derives voltage feedback from an attenuator connected to the feedback voltage.
  • Load Current or Voltage Regulation: Limit amplifiers respond to the difference between the either feedback signal and the corresponding limit commands. The resulting signal is the SCR delay angle command signal, SIG HI. The CTRCT2 may be configured to regulate load voltage in addition to providing overcurrent trip.
  • Overcurrent Trip with Manual or Automatic Reset: A current trip feature inhibits the SCR firing board when the current exceeds the threshold set by the board-mounted potentiometer. This feature shuts down the system in the event of a short circuit . The regulator board may be configured to automatically reset after a predetermined dead time (typically several seconds) or latch until a manual reset is asserted.
  • Soft-Start Ramp: The CTRCT-2 includes a ramp potentiometer which controls the soft-start ramp time. The soft-start or soft-stop time constants are determined by a resistor and capacitor.
  • CTRCT-2 Status Interface: The CTRCT-2 includes an auxiliary connector with three open-collector transistors indicating the status of the overcurrent , manual trip, and current limit signals. Connections to the circuit common, +12 and +24 V rails are provided to drive lamps, relay coils, or other monitoring apparatus.
  • Current Command Signal: The current command signal (or voltage command signal, if configured for the CTRCT-2) may be configured for a variety of common ranges including 0-12 V, 0-10 V, or 4-20 mA.
  • Board Construction: All circuit boards are assembled at the Enerpro plant in Goleta, California and are manufactured by a UL-approved fabricator from 2.4 mm thick FR4 fire resistant fiberglass epoxy laminate. All boards are conformal coated (MIL-1-46058, Type UR).


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