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Operating Manual: OP-0106
August 2019
Enerpro Document No: OP-0106, Rev. B
Page 1 of 14
ECO #19-11089; Release Date: 08/02/2019
Operating Manual: Four-SCR General Purpose Gate Firing Board
FCRO4100 Revision L
Introduction
This manual describes the salient features and specifications of the FCRO4100 firing board, including
typical firing circuit signal waveforms and a checkout procedure.
Product Description
1.0
Application
The FCRO4100 board is a four-SCR firing board suitable for use with single-phase AC
controllers, center-tap or full wave rectifiers. The firing board responds to a voltage or current
delay angle command signal (SIG HI) to produce four delayed, isolated, 180°-spaced high-
current SCR gate firing pulses. An optional regulator circuit provides voltage or current regulation
and optional plug-in regulator boards provide voltage/current limiting or polarity transition
functionality for four-quadrant rectifiers.
2.0
ASIC-Based Firing Circuit
All firing circuit logic is contained in a custom 20-pin ASIC. Additional detail on the firing circuit
theory is contained in a separate engineering society paper
1
.
3.0
Board Mounted Connectors
3.1.
Gate/Cathode and Control Power Connector
Six-position header J1 provides the connections for the +X1 SCR (load connected cathode) at
positions 1 and 2 and for the -X1 SCR (line connected cathode) at positions 5 and 6.
Five-position header J2 provides the connections for the +X2 SCR (load connected cathode) at
positions 1 and 2 and for the –X2 SCR (line connected cathode) at positions 4 and 5.
The board-mounted 24 VA power supply transformer (T1) is normally energized by connecting
the mains voltage at J3. The gate firing signals are locked to the mains waveform through the
power control transformer, hence, the board power must be in phase with the mains voltage.
3.2.
Control Signal Connector
The delay angle command (SIG HI), instant and soft inhibit controls, voltage and current feedback
signal, and auxiliary power connections are available through J4, a 12-position Mate-N-Lok™
connector. The pinout of this connector is detailed in drawing E168 Rev L.
3.3.
Feedback Signal Connector and Plug-In Regulator Board Connector
The FCRO4100 board can accept voltage and current feedback in certain configurations.
Ground-referenced voltage feedback and current limit command signals enter on J5 pins 4 and 5
respectively. Current feedback signals from CTs enter on J5 pins 1 and 2 and connect to the
associated bridge rectifier and burden resistor. A 14-position connector J6 provides an interface
for plug-in regulator boards; see section 7.0 for operational information regarding regulation
capabilities.
3.4.
Auxiliary Firing Board Connector
Six-position MTA header J7 provides board power, circuit common, and SCR gate signals that
connect to the FCOAUX60 auxiliary firing board to provide four-quadrant operation. See section
6.0 for operational information regarding four-quadrant applications.
1
Bourbeau, F. J., “Phase Control Thyristor Firing Circuit: Theory and Applications”, Power Quality ’89, Long Beach, California.
