The FCRO4100 provides phase-angle control of single-phase SCR AC controllers, center tapped rectifiers, and two- or four-quadrant bridge rectifiers for a wide variety of power control applications. The board features four isolated gate drives, independently configurable soft start/soft stop control inputs, and an analog delay angle command input configurable for a variety of common voltage or current ranges. Optional plug-in regulator boards provide regulation functionality ( VRCL1P-1 board) or timed polarity transition inhibit for four-quadrant rectifier applications ( PTIR-1 board).


  • Industry Standard ASIC-Based Design
  • Fully Connectorized
  • Independently Configurable
    Soft-Start and Soft-Stop
  • Isolated Gate Drive Circuitry
  • Power-On Reset Protection
  • Low Signal Inhibit


The FCRO4100 includes the following operational features:

  • Analog Delay Angle Command Signal (SIG HI): Users may choose a variety of DC control signal ranges including 0-5 V, 4-20 mA, or custom ranges.
  • Soft-Start and Soft-Stop: Upon soft-start, SCR firing is enabled and the delay angle command ramps from the maximum value to the setpoint value determined by the SIG HI command signal. Upon soft-stop, the delay angle ramps from the setpoint value to the maximum value after which SCR firing is inhibited.
  • Instant Enable and Inhibit: A contact closure (relay, switch, transistor) instantly enables or inhibits SCR firing at the delay angle commensurate with the SIG HI command signal.
  • 50/60 Hz Frequency Selection: Operation from 50 or 60 Hz mains may be selected via an onboard jumper.
  • High Current Picket Fence Gate Drive: The transformer-isolated gate drive circuits provide a hard firing initial 15 V open circuit/1.5 A short circuit firing pulse followed by sustaining "back porch" pulses at 7 V open circuit/0.5 A short circuit. The gate pulse burst frequency is 256 times the mains voltage frequency.
  • Power-On Reset: A special circuit prevents unintentional SCR gating upon board power-up.
  • Analog Delay Determinator Circuit: Enerpro's gate delay determinator circuit is based on an analog PLL circuit and implemented with a proprietary ASIC. This circuit adjusts the gate delay firing angle in negative proportion to the SIG HI delay angle command signal.
  • Plug-In Regulator Boards : Two plug-in regulator boards are available for the FCRO4100 . The VRCL1P-1 board provides voltage regulation and current limit functionality. The PTIR-1 board provides voltage regulation and allows the user to program a specific dead time between switching polarity of an 8- SCR bridge rectifier.
  • SImple Control Power Connection: The FCRO4100 derives its control power from the same ac source controlled by the SCRs. An onboard transformer steps down 120, 240, or 480 Vac mains and also provides the phase reference signal for the firing circuit.
  • 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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