OPERATING PROCEDURES
TURBINE TRIP
I-E96-322A
5 - 3
while the lower contact closes the valve. Use the 4 to 20 milli-
amp position output to determine the valve position.
4. To return to automatic mode, the MFP module must be
communicating with the HSS module. If hard manual mode
was selected through function code 55, specification S13 must
be returned to auto mode, <S13> = 0. Finally, the operator
must match the D/A converter output value (block number
N+1) with the current position demand from the MFP module.
NOTE: If the HSS module enters hard manual mode by losing com-
munication to the MFP module, the HSS module will exit hard man-
ual mode when the MFP module establishes communication with
the HSS module, and when position demands from the MFP and
HSS modules match. The MFP module resumes automatic opera-
tion from the valve position held during manual operation.
TURBINE TRIP
Turbine trip provides quick shutdown by providing a way to
drive the throttle valve closed. The trip bias circuit overrides
position control from the HSS microprocessor and drives the
valve closed. To drive the valve closed, close the trip bias switch
(customer installed) to apply 24 VDC to the trip bias digital
input.
