TP-5737 5/01 75Section 7 Component Testing and Adjustment
generator sets and reverse the direction of the
generator load line through the current
transformer or reverse the transformer leads
on unit no. 1.
c. Restart the generator sets and recheck the
droop on unit no. 1.
d. Set the reactive droop compensator rheostat to
a value at approximately 4% below rated
voltage at full load. As an example, the voltage
droops (decreases) 19.2 volts on a 480-volt
system at full load or 9.6 volts at one half load.
Use the following formula for loads other than
full load:
Rated Voltage x 0.04 x Actual Load (expressed
as a % of full load) = Voltage Droop
Note: With full load 0.8 power factor, a droop of
3--5% should be adequate for
paralleling.
6. Repeat step 5 for generator set no. 2. Adjust unit
no. 2 where the voltage droop is equal and at the
same point as on unit no. 1. The two units share
reactive currents proportionately after correctly
performing this procedure.
7. If reactive load is not available, go to
Section 7.12.3, Reactive Droop Compensator
Alternate Adjustment Procedure. If reactive load is
available, go to Section 7.12.4, Testing.
7.12.3 Reactive Droop Compensator
Alternate Adjustment Procedure
Initially calibrate each generator set using the following
procedure.
1. Turn the reactive droop compensator rheostat on
generator set no. 1 to the minimum setting.
2. Remove the controller cover. Move the voltage
sensing lead from V7 to V9 at the AC fuse terminal
block.
3. Remove any load connected to the generator set.
4. Start the generator set by placing the generator
master switch in the RUN position.
5. Use the controller or remote voltage adjusting
potentiometer on each generator set to fine adjust
voltage as necessary.
6. Apply resistive load (1.0 power factor) until
reaching rated current.
7. Adjust the reactive droop compensator rheostat to
achieve a 4% droop (decrease) in voltage.
8. Remove the resistive load.
9. Stop the generator set by placing the generator
master switch in the OFF position.
10. Return the voltage sensing lead from V9 to V7 at
the AC fuse terminal block.
11. Replace the controller cover.
12. Repeat steps 1--11 for generator set no. 2.
7.12.4 Testing
Use the following procedure to check that the generator
sets share the reactive load proportionately.
1. Parallel the units at one half to full load. Verify that
each unit carries equal kW load or a load
proportional to its capacity using the wattmeter
readings. If load unbalance exists, adjust and
recheck the electronic governor throttle control to
correctly balance loading. Engine speed
determines load sharing ability.
2. With the load balanced, check the ammeters for
equal current or proportional according to capacity.
If the currents are incorrect, adjust the reactive
droop compensator rheostat reducing the current
of the unit with the highest reading. Reduce the
current to an equal division or proportionately.
3. Stop each generator set by placing the generator
master switch in the OFF position.
Note: Step 1 balances the load using the electronic
governor and step 2 balances the current using
the reactive droop compensator. Consider these
settings optimum for parallel operation.
Note: Voltage must droop (decrease) on lagging power
factor loads (inductive loads). A small change in
voltage is acceptable on unity power factor loads
(resistive loads).
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