Insufficient Magnetic Speed Sensor Signal; Electromagnetic Compatibility (Emc) - KIRLOSKAR DV Series O & M Manual

SYMPTOM
Actuator does not
energize fully.
Engine remains
below desired
governed speed.
SYSTEM TROUBLESHOOTING

Insufficient Magnetic Speed Sensor Signal

A strong magnetic speed sensor signal will eliminate the possibility of missed or extra pulses. The speed
control unit will govern well with 0.5 volts RMS speed sensor signal. A speed sensor signal of 3 volts RMS
or greater at governed speed is recommended. Measurement of the signal is made at Terminals C and D.
The amplitude of the speed sensor signal can be raised by reducing the gap between the speed sensor tip
and the engine rind gear. The gap should not be any smaller than 0.020 in (0.45 mm). When the engine is
stopped, back the speed sensor out by 3/4 turn after touching the ring gear tooth to achieve a satisfactory
air gap.

Electromagnetic Compatibility (EMC)

EMI SUSCEPTIBILITY - The governor system can be adversely affected by large interfering signals that
are conducted through the cabling or through direct radiation into the control circuits.
All GAC speed control units contain filters and shielding designed to protect the units sensitive circuits
from moderate external interfering sources.
Although it is difficult to predict levels of interference, applications that include magnetos, solid state
ignition systems, radio transmitters, voltage regulators or battery chargers should be considered suspect
as possible interfering sources.
If it is suspected that external fields, either those that are radiated or conducted, are or will affect the
governor systems operation, it is recommended to use shielded cable for all external connections. Be
sure that only one end of the shields, including the speed sensor shield, is connected to a single point on
the case of the speed control unit. Mount the speed control unit to a grounded metal back plate or place
it in a sealed metal box.
Radiation is when the interfering signal is radiated directly through space to the governing system. To
isolate the governor system electronics from this type of interference source, a metal shield or a solid
metal container is usually effective.
Conduction is when the interfering signal is conducted through the interconnecting wiring to the governor
system electronics. Shielded cables and installing filters are common remedies.
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TEST
1. Measure the voltage at the battery
while cranking.
2. Momentarily connect Terminals A
and F. The actuator should move to 2. Actuator or linkage binding.
the full fuel position.
1. Measure the actuator output.
Terminals A & B, while running
under governor control.
PROBABLE FAULT
1. If the voltage is less than 7V for a 12V
system, or 14V for a 24V system,
replace the battery if it is weak or
undersized.
1. Actuator or battery wiring in error.
3. Defective actuator. See actuator
troubleshooting.
4. Fuse opens. Check for short in
actuator or actuator wiring harness.
1. If voltage measurement is within
approximately 2 volts of the battery
supply voltage, then fuel control
restricted from reaching full fuel
position. Possibly due to interference
from the mechanical governor,
carburetor spring or linkage alignment.
2. Speed setting too low.