The FCOVF6100 variable frequency firing board provides the functionality of the industry-standard FCOG6100 firing board for applications with variable-frequency AC mains. An onboard frequency compensation scheme makes the firing circuit less sensitive to line frequency variations while an isolated DC-DC converter provides enhanced control power flexibility. The FCOVF6100 is offered in a standard 30-140 Hz frequency of operation range and customer-specific ranges to 600Hz.


  • Industry Standard ASIC-Based Design
  • Variable frequency range of operation: 30-140 Hz (nominal) (others available)
  • Fully Connectorized
  • Independently Configurable Soft-Start and Soft-Stop
  • Isolated Gate Drive Circuitry
  • Phase Loss Protection 10:1 Supply Voltage Frequency
  • Optional DC/DC Converter for Board Power


The FCOVF6100  includes the following features:

  • Frequency Insensitivity: A frequency-tovoltage converter acts in concert with the delay angle determinator circuit to reduce delay angle variance over the operating frequency range. This scheme limits delay angle variance to approximately 3 over a frequency range of 30 to 120 Hz.
  • 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.
  • 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 signal.
  • 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 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 FCOVF6100 board is typically configured to accept 24 or 48 VDC control power. In this configuration, an onboard 20 W DC-DC converter rated for 1600 V isolation (with a voltage limiting Zener preregulator ) creates the necessary 30 VDC and 15 VDC rail voltages on the firing board. The customer may alternatively supply 30 and 15 VDC rails directly.
  • 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).




  • Generator Exciters
  • Battery Chargers
  • Wind Turbine Controllers
  • DC Drives

Ordering Guide

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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