I.B. 48008
Page 5
Effective 11/97
The minimum output voltage can be adjusted from 50% to
70% of nominal voltage (125 or 250 VDC) with a potenti-
ometer (P1) on the printed circuit board. See Figure 5.
Full voltage control is achieved by the addition of a
potentiometer (P2), typically mounted on the front panel of
the power supply cabinet. The range of local voltage
control adjustment is coordinated with the minimum output
voltage adjustment (P1) to produce the desired minimum
and maximum output voltages.
Fig. 4 Mark V Controller Schematic
When the motor is running at rated speed and the line
contactor (M) opens, the gating must be inhibited to SCRs
QA1 to QC2. To do this, voltage is removed from terminal
115 and IN-.
If gating is not inhibited, the motor will continue to supply
excitation voltage until it slows to about 50% speed.
