One side of the secondary of all CTs must be earthed. The earth connection should be made on the side of the secondary facing the protected object. The polarity of the CTs must be in accordance with the following diagram.
With the prime mover operating at rated speed and no load, record the voltage
across the actuator terminals 9 (+) and 10 (–). Shut down the prime mover and
activate the Failed Speed Signal Override by closing the override contact. The
voltage to the actuator should now be adjustable by the START FUEL LIMIT
potentiometer. Set the actuator voltage about 30% higher than the voltage
obtained at rated speed for forward-acting controls and 30% lower than rated
speed voltage for reverse-acting controls. Remove the Failed Speed Signal
Override contact if not required to start the prime mover.
Start the prime mover and observe the start time, overshoot of speed setting, and
exhaust smoke obtained. If the prime mover does not start, turn the START
FUEL LIMIT potentiometer slightly clockwise until the prime mover starts. The
START FUEL LIMIT may be adjusted as required to optimize the prime-mover
starting characteristics. The fuel-limiting function is turned off automatically when
the speed control takes over.
For prime movers not requiring start-fuel limiting, the START FUEL
LIMIT function can be deactivated by turning the potentiometer fully
clockwise (be careful not to overtorque the pot).
Speed Sensor Check
If the sensor is a magnetic pickup, measure the voltage across terminals 7 and 8
to be sure there is a minimum of 1.0 volts at cranking speed, and a maximum of
30 Vrms at rated speed. If the voltage exceeds 30 volts, increase the gap of the
speed sensor, and be sure that there is still a minimum of 1.0 volts at cranking
speed.
Droop Adjustment
The amount of droop is not critical in many installations. If the engine needs to
run in droop but the amount is not critical set the droop potentiometer in midposition, then adjust load with the speed-setting potentiometer.
When paralleled with an infinite bus, the generator frequency cannot change, and
unless a load- sensing module is being used, the control must be in droop to
maintain stable operation. With the droop potentiometer at mid-position, parallel
the generator, then increase the Rated Speed potentiometer until the desired
amount of load on the engine is achieved.
Too much droop will cause the engine to overspeed should the load be suddenly
lost. Excessive droop will also cause the engine to be sluggish in response to
load changes.
