TM 5-6115-400-35
(2) Test the transformer for continuity using
an ohmmeter.
(3) The magnetic amplifier, operating at
1,000 cps, has 4 control windings and an
(3) Test the transformer for grounds by
output or power winding. Its purpose is to
testing between one lead of each winding
mix or totalize the control error signals
and the core with a multimeter.
and amplify the result for use by the servo
(4) Test the transformer for shorted windings
actuator. The control windings include
by testing between one lead of the
frequency error winding, negative feed-
secondary winding and one lead of the
back winding, load sharing winding, and
primary winding.
bias winding. The level of these DC
(6) Refer to paragraph 73c (4) to test the
control windings affects the output of the
power winding which is the input to the
e. Inspection and Repair.
electro-hydraulic actuator.
(1) Inspect the resistor for damaged ter-
b. Removal. Refer to figure 132 to remove the electric
minals, defective insulation and other
control unit.
visible damage.
(2) Inspect the transformer for cracks, breaks,
90. Load Measurement Unit
broken terminals and evidence of
overheating.
a. The load measurement unit, consisting of a
(a) A defective load measurement unit should
three phase transformer, diode rectifiers and a load
be replaced.
resistor, measures the total load on the generator set
regardless of power factor or phase. The DC output of
91. Electro-Hydraulic Actuator
this unit is connected to the feedback and paralleling cir-
cuits of the LEH control unit.
a. General.
(1) The actuator (fig.
load measurement unit to other components.
intelligence from the magamp output in
the electric control unit and converts
remove and install the load measurement unit.
these signals to an actuator motion that -
positions the engine throttle properly. The
actuator is composed of a control valve, a
piston, and a linkage assembly.
(2) The electro-hydraulic control valve
receives its control signals from the
magamp output in the electrical control
unit. The control valve converts the
proportional push pull electrical input to a
proportional push pull hydraulic output.
The control valve requires a constant hy-
draulic input of 2 gallons/minute at 300
psi.
(3) The push pull hydraulic output of the control
valve operates a piston. Whenever the push
Figure 133. Load measurement unit.
pull hydraulic signal is unbalanced, the piston
d. Testing.
will move in a direction depending upon
(1) Test the load resistor using an ohmmeter.
173
