Woodward 9907-026, Product Manual

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Load Sharing Module (Analog Output) Manual 02029
14 Woodward
If the load signal voltage cannot be raised to 6 volts, and the phasing has
been checked and is correct, it will be necessary to use a lower load signal
voltage. Set the load signal voltages of all generator sets in the system to
the same voltage.
When paralleled, adjustment of a generator set's LOAD GAIN potentiometer
clockwise will cause that generator set to carry less load. If stability
problems occur when paralleled at a particular load signal voltage, reduce
the load signal voltage by adjusting the LOAD GAIN potentiometer and set
the load signal voltage of all other generator sets in the system to the same
voltage. When the load signal voltages of all generator sets in a system are
reduced, the load sharing gain will be reduced and this may result in some
loss of load sharing sensitivity.
It may be necessary to reduce the load signal voltage of each unit in the
system to as low as three volts in cases of extremely poor system dynamics.
If your system requires a load signal voltage as low as three volts, consult
the Woodward Governor Company for suggestions for possible remedies.
The most accurate calibration is made at full load. However, if it is
not possible to run the generator set at full load, run it at less than
full load, and reduce the voltage readings given in this calibration
procedure proportionally. For example, run a 2 kW gen-set at 1 kW
and divide all voltages given in this calibration procedure by 2. If you
reduce the load, however, be sure to reduce it the same amount
throughout this calibration procedure.
Droop Adjustment
Droop is usually expressed as a percentage. The droop in a Load Sharing
Module is calculated by the following formula.
% Droop =
No Load Speed – Full Load
No Load Speed
When the generator set is to be operated in the droop mode, the DROOP
potentiometer must be adjusted. The method of setting droop depends on
whether the load of the generator set is an isolated load or an infinite bus.
Setting Droop for an Isolated Load
1.
Open the OPEN FOR DROOP SWITCH (or disconnect the wires from
terminals 15 and 16).
2.
Start the engine and adjust the RATED SPEED potentiometer on the EPG
for rated speed with no load.
3.
Apply full load.
4.
Adjust the DROOP potentiometer to give the desired speed.
For example: operating at 60 Hz, 57 Hz at full load indicates 5% droop.
If only 50% loading is possible, 58.5 Hz would indicate 5% droop. See
Figure 3-2. Droop Adjustment.