
64 SEBU8219-01
Operation Section
Generator Operation
•
Both generator
s have the same phase
rotation when the lights blink in unison. The
first condition of “Initial Start-Up” has been
met.
2. Adjust the frequency.
The units that will be operating in parallel must
operate at the same speed. Speed is proportional
to the altern
ating current frequency.
a. Allow each electric set to run under load for
about 30 minu
tes.
b. Adjust the control in order to give the rated
frequency at
full load.
c. Remove the load and check the high idle
speed. The hi
gh idle speed should be
approximately 2 to 5 percent above full load
speed for generators that are equipped with
droop. If th
ese speeds can not be obtained,
contact your Caterpillar dealer.
d. For the most
consistent results, repeat 2.b
and 2.c until the second condition of “Initial
Start-Up” has been met.
3. Adjust the voltage.The potentiometers should
be at the initial settings. Refer to Ope ration and
Maintenan
ce Manual, “Voltage R egulators”.
Note: Make sure that the speed droop is identical for
all of the e
ngines before adjustments are made to
the generator.
a. Preset th
e unit for parallel operation by
connecting the current transformer to S1 and
S2 of the connector J2. Set potentiometer P1
for quadr
ature droop in the center position.
Apply the rated load. The voltage should drop
for 2% to 3%. Switch the positions of the
two inco
ming secondary wires of the current
transformer if the voltage increases.
b. The no-l
oad voltages should be identical for all
the generators that are operating in parallel.
Connect the generators in parallel. Try to obtain
a0kWpow
er exchange by adjusting the speed
of the generator. Try to minimize the circulating
currents between generators by altering the
voltag
e setting with potentiometer P2 or Rhe
on one of the generators.
Note: D
o not change the voltage settings after
this step.
c. Apply the avail
able load. The setting is correct
only if a reactive load is available. Equalize the
Kilowatts or divide the rated power of the units
proportional
ly by altering the speed. Alter the
quadrature droop potentiometer (P1) in order
to equalize the currents or divide the currents.
Starting Multiple Units
Use the procedure for starting single units in order
to start multiple units. Refer to Operation Section,
“Single Unit
Operation”.
Paralleling
Multiple Units
Units may be paralleled at no load. Units may also
be parallele
d with units under load. After the initial
conditions for start-up are satisfied, verify for the
following requirements:
•
Generators must have voltage droop compensation
or cross current compensation.
1. Start the unit which will be paralleled.
2. Turn on the s
ynchronizer lights.
3. After the engine has run a few minutes, bring the
engine up to
synchronous speed. This means
that the frequency of the incoming unit will be the
same frequency as the unit that is on-line. The
synchroni
zing lights will begin to blink.
Note: The frequency of the incoming unit should be
slightly g
reater than the line frequency. This will allow
the incoming unit to assume some of the load instead
of adding to the system load.
4. By using the control, adjust the engine speed until
the lights blink very slowly.
5. The lights are off when the voltages of the two
units are in-phase. At this point, very quickly close
the break
er while the lights are out.
6. Use the controls in order to share kW load
between e
ngines.
7. Generator temperature will be stabilized in
approxi
mately one hour. After the generator
temperature has been stabilized, adjust the
voltage droop rheostat of each generator. This
will sha
re the reactive load and this will limit
the circulating currents. Less droop increases
the reactive current that is carried by the
genera
tor. Adjusting the voltage droop rheostat
in a counterclockwise direction will decrease the
droop. Adjusting the voltage droop rheostat in a
clockw
ise direction will increase droop.