The FCOG6100 provides economical and reliable phase-angle control of SCR AC controllers and DC converters operated from three-phase mains. The board features six 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. A variety of current and voltage regulator boards are available in addition to auxiliary firing boards for remote or parallel SCR arrangements.


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


The FCOG6100 includes the following features:

  • Analog Delay Angle Command Signal (SIG HI): Users may choose a variety of DC control signal ranges including 0-5 V, 0-10 V, 4-20 mA, or custom ranges.
  • Power-On Reset: A special circuit prevents unintentional SCR gating upon board power-up.
  • 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.
  • Phase Loss Inhibit: A phase loss circuit instantly inhibits SCR firing if a loss of one or more phases or gross phase imbalance is sensed on the AC line. Firing will soft-start when such a fault is cleared.
  • 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.
  • Phase Sequence Insensitivity: SCR gating is unaffected by mains voltage phase sequence.
  • Enhanced Frequency Insensitivity: A new compensation circuit reduces delay angle variance with respect to frequency. The gate drive angle decreases approximately 5° for a frequency change from 60 to 50 Hz, whereas the delay angle of previous configurations decreased 12.5° over the same frequency range.
  • High Current Picket Fence Gate Drive: The transformer-isolated gate drive circuits provide a hard firing initial 15 V open circuit/1.8 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 384 times the mains voltage frequency.
  • Analog Delay Determinator Circuit: Enerpro’s gate delay determinator circuit is based on the Ainsworth three-phase PLL circuit and implemented with a proprietary ASIC. This circuit adjusts the gate delay firing angle in negative proportion to the SIG HI command. Gate drive phase balance is typically less than ±1°
  • Flexible Control Power Options: The FCOG6100 may be powered from an external 30 VDC or 24 VAC source. With the addition of an onboard transformer, the board may be powered from a 120 V, 240 V, 380 V, or 480 V external source. Board power may also be obtained directly from the connections to the SCR cathodes.
  • Board Construction: All circuit boards are assembled at the Enerpro plant in Goleta, California and are manufactured by a UL-approved fabricator from 0.093-inch thick FR4 fire resistant fiberglass epoxy laminate. All boards are conformal coated (MIL-1-46058, Type UR).


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