108 Rockwell Automation Publication 7000-UM202D-EN-P - May 2018
Chapter 2 Power Component Definition and Maintenance
Self-Powered Gate Driver
Board – SPGDB
This board is a component in drives using SCRs as the rectifying device on the
input of the drive. The SCRs require a gating pulse to turn on, and this is
achieved by using the SPGDB.
The SPGDB receives signals from the drive processor via a light signal
transmitted through a fiber optic cable. The power source for the SPGDB is
from the SCR snubber network, a Rockwell Automation patented design. This
unique design gives the SPGDB the ability to conserve the amount of energy
that it supplies to the SCR. This reduces the amount of energy required by the
drive to operate, thus making the drive more efficient.
This board also determines the health of the SCR. The SPGDB has the
hardware necessary to diagnose SCR conditions and relay the status to the
processor via a fail-safe light signal along a fiber optic cable.
Board Calibration
This board requires no field calibration.
Test Points
The yellow LED (LED 1) on the SGPDB indicates that the controlled SCR
has a gating current flowing, which turns on the SCR.
TP1 SCR gate output (attach oscilloscope between TP1 and TP2 to see gating pulses)
TP2 SCR cathode output
TP3 Common reference point for all other test point measurements, except for TP1, which uses TP2 as its
reference point
TP4 The positive 20 V rail used for the SPGDB operation
TP5 The positive 5 V rail used for the SPGDB operation
TP6 The sense voltage taken from the sense resistor across the SCR being controlled
TP7 Trigger signal, which remains active for a fixed period of time after the SCR being controlled, has
turned on and the voltage across it has collapsed
TP8 Internal gating signal that indirectly turns on the SCR that is being controlled
TP9 Gating signal received from the commanding drive control board, through the appropriate fiber
optic cable
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