The FCOG61HV firing board combines the circuitry of the FCOG6100 firing board with high voltage tolerant, high output gate pulse transformers and increased creepage distances. This provides enhanced isolation for AC line voltages to 900 Vac and enhanced gate trigger current for large area devices.


  • Insensitive to phase sequence and mains voltage distortion
  • High gate isolation
  • Soft and instant start/stop functions
  • Phase loss inhibit
  • 50/60 Hz operation


The FCOG61HV  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 commanded by the SIG HI delay angle command.
  • Enhanced Frequency Insensitivity: An improved frequency 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.
  • Phase Sequence Insensitivity: SCR gating is unaffected by mains voltage phase sequence.
  • High Current Picket Fence Gate Drive: The transformer-isolated gate drive circuits provide a hard firing (0.9 A/mS) initial pulse followed by sustaining "back porch" pulses. The gate pulse burst frequency is 384 times the mains voltage frequency.
  • Enhanced Gate Drive Isolation: Larger ferrite cores and three-flange bobbins in the dual pulse modules provide higher isolation while a larger pulse module package gives enhanced creepage distance (20 mm) between the ac mains and the low voltage control electronics.
  • 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 FCOG61HV is powered from an external 30 VDC or 24 VAC source.
  • 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).

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.

Typical applications for the FCOG6100 include plating rectifiers, battery chargers, wind turbine controllers, DC motor drives, semiconverters, UPS systems, and transformer primary controllers.

Operational Features
The FCOG6100 includes the following features:
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