Woodward TG-10E, Installation And Operation Manual

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TG-10E/-13E/-17E Actuator Manual 04045
28 Woodward
Figure 6-1. Actuator Test Circuit
8.
If necessary to provide drive or oil pressure to the actuator—depending on
the type of drive and source of oil pressure used on the particular TG—start
the turbine UNDER MANUAL CONTROL, following the turbine
manufacturer’s instructions.
9.
Control prime mover speed MANUALLY and bring turbine speed to a SLOW
SPEED to develop actuator working pressure.
10. Slowly rotate the potentiometer through its range and observe the actuator’s
shaft movement.
The terminal shaft must move through its range of travel as the
potentiometer is rotated and must take the same position each time for a
given potentiometer setting.
If the terminal shaft positions or operates erratically, the problem is in the
actuator.
11. Check the removable cover filter element for possible clogging if actuator
control is sluggish or just stops. The cover filter filters all internal oil. Clean
and back-flush the filter in fuel oil or kerosene and reinstall. Remove this
filter only after the turbine has stopped rotating and the oil has been drained
from the actuator.
If an external oil supply is used, there is no cover filter element. Instead, the
actuator is fitted with a –6 filter fitting (70 µm absolute) and a –10 drain fitting.
Check the filter for possible clogging, clean and back-flush the filter with fuel
oil or kerosene, and re-install.
The TG actuator is also fitted with a filter screen (18) as a secondary filter,
which is part of the pilot-valve bushing. It is used to protect the nozzle supply
orifice from possible clogging. Checking the secondary filter requires partial
disassembly and recalibration of the actuator. See Chapter 4, Procedure for
Cleaning the Filter Screens and the Pilot-Valve Plunger Orifice, as well as
Chapter 4, Calibration Procedure.
Dirty oil causes most actuator troubles. Use new, clean, filtered oil. Oil
containers must be perfectly clean. Oil contaminated with water breaks down
rapidly, causing foaming and corrosion of internal parts. This usually results
in sluggish, erratic, or complete loss of actuator control.