that unit reads approximately 40 per cent of the total
4. Turn the vernier throttle knob until both units are
operating at approximately the same frequency as
indicated by the slow change in the brilliancy of the
9. Rotate the voltage regulator rheostat control on the
incoming generator clockwise to raise the voltage until
the ammeters read the same on both units.
5. When the synchronizing lamps glow and then go
out at a very slow rate, time the dark interval. Then, in
NOTE: If a load was not added during
the middle of this interval, turn the circuit breaker
paralleling, the total of the two ammeter
control to the on position. This places the incoming
readings should be the same as the reading
generator set on the line, with no load. The proper
before paralleling. Readjust the voltage regula-
share of the existing load must now be placed on this
tor rheostat on the incoming generator, if
6. The division of the kilowatt load between the
10. To reset the load voltage, turn the voltage regulator
alternating current generators operating in parallel
rheostat controls slowly on each unit. It is necessary to
depends on the power supplied by the engines to the
turn the controls the same amount and in the same
generators as controlled by the engine governors and
direction to keep the reactive current equally divided.
is practically independent of the generator excitation.
Divide the kilowatt load between the generators by
Power generator sets with different capacities can also
-turning the vernier throttle knob counterclockwise on
be paralleled by dividing the load proportionately to
the incoming generator and clockwise on the generator
that has been carrying the load (to keep the frequency
of the generators constant) until both ammeters read
the same, indicating that each generator is carrying its
proper percentage of the total K.W. load.
The procedure for stopping a power generator set or
taking it out of parallel is as follows:
7. The division of the reactive KVA load depends on
1. Turn off all of the load on the generator when
the generator excitation as controlled by the voltage
stopping a single engine unit.
regulator. Divide the reactive load between the
generators by turning the voltage regulator rheostat
2. Shift the load from the generator when taking it out
control on the incoming generator (generally clockwise
of parallel operation by turning the vernier throttle
to raise the voltage) until the ammeters read the same
knob until the ammeter reads approximately zero.
on both generator sets and the sum of the readings is
3. Place the circuit breaker control in the off position.
NOTE: The generator sets are equipped with a
4. Turn the voltage regulator rheostat control in a
counterclockwise direction to the limit of its travel.
series with the voltage coil of the regulator
(cross-current compensation) which equalizes
5. Press the throttle button and turn the throttle
most but not all of the reactive KVA load
control to stop to shut-down the engine.
between the generators.
NOTE: When performing a tune-up on a
generator set that will be operated in parallel
8. When the load is 80 per cent power factor lagging
with another unit, adjust the speed droop as
(motor and a few lights only), turn the vernier throttle
specified in Engine Tune-Up.
knob on the incoming generator until the ammeter on