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 CTRCT-2 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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