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Manual 26839V2
Hardware/Operating System Faults
Most 505 problems are caused by wiring problems. Carefully and thoroughly check all wiring connections
at both ends. Be very careful when installing wires into the 505 control terminal blocks. Check all shields
for proper grounding.
All inputs and outputs can be measured directly at the terminal strips. In addition, from the Hardware
pages, the display will show what the 505 measures. This comparison can be used to determine if the
505 is interpreting the input signal correctly. The Hardware pages on the display can be used to monitor
and adjust analog inputs and outputs, monitor speed inputs, monitor and adjust actuator outputs, monitor
contact inputs, and monitor and force relay outputs.
Contact inputs can be verified by measuring the voltage at the terminal blocks. The contact power supply
voltage should measure approximately 24 VDC from any contact (+) terminal to the contact GND terminal
(11). If 24 VDC is not the voltage measured, disconnect all wiring to the 505 except input power, then re-
measure this power supply voltage. If 24 VDC is not the voltage measured, check for wiring problems. If
24 VDC is not measured across the contact input (+) and contact GND terminal (11) with input wiring
disconnected, replace the 505.
The operation of a contact input to the 505 can be checked by verifying that the voltage from the contact
input's (+) terminal measures 24 VDC with respect to the contact input GND, terminal (11), when the
external contact is closed.
Any 4–20 mA input or output can be checked by placing a milliamp meter in series with the input or
output.
Refer to Volume 1 Chapter 2 for actuator wiring concerns or questions.
If the serial communications line is not working, check the wiring first. Then check the Program Mode
entries for matching communications setup.
If, while trying to adjust the Speed Setpoint in the Run Mode, the ADJ up and ADJ down keys will not
work, check to make sure that CAS (cascade control) and RMT (remote control) are both disabled.
If the system's steam valve is unsteady or hunts, try manually positioning the steam valve by closing the
valve limiter. If the steam valve is blocked in this manner and the actuator output is steady but the turbine
still hunts, then the problem is outside the governor. If an actuator hunts, or appears sticky, it may need
dither (especially TM type).
Woodward
Released
Chapter 14.
General
EXPLOSION HAZARD—Do not connect or disconnect while circuit is
live unless area is known to be non-hazardous.
RISQUE D'EXPLOSION—Ne pas raccorder ni débrancher
tant que l'installation est sous tension, sauf en cas
l'ambiance est décidément non dangereuse.
Wiring Problems
Control Adjustments
505 Digital Control for Steam Turbines
83
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