(10) To remove a generator set from parallel operation,
(6) Carefully observe the synchronizing lights of the
place the circuit breaker switch of the set in the OPEN posi-
"on-coming" set and, at the instant both lights go dark, place
the CKT BRK switch (30) of the "on-coming" set to the
CLOSE position. When the CKT BRK indicator light (31)
e. Parallel Operation (Load Transfer). The following
illuminates, the sets are operating in parallel.
method of parallel operation is to be used when it is necessary
to transfer the load from one set to the other without inter-
indicate precentages and do not in-
d i c a t e true KW and ampere
Visually check that the power cable
and parallel cable are in accordance
(7) With no external load on the paralleled sets, adjust
the frequency adjust rheostat, (29) of the "on-coming" set
attached as indicated, shutdown the
until both rated load meters (kilowatt) read zero. Adjust the
"on-line" set and follow instructions
voltage adjust rheostat of the "on-coming" set until the per-
cent of rated current meters (ammeters) on both sets read
zero. Turning counterclockwise will decrease readings.
(8) Apply load to the sets. The kilowatt load should
Do not attempt load connects in
divide so that the load on each set is equal. If the load and
current are not shared equally, adjust the voltage and fre-
off and no other external voltage is
quency rheostats of the "on-coming" set until load and cur-
applied to the load.
rent are divided equally between the generator sets.
(1) The set in operation shall be designated as "on-line"
(9) The current should divide so that the observed dif-
and the sets placed in parallel operation shall be designated
ference between the current on any phase between the "on-
line" and "on-coming" sets is not more than 20 percent.
If the readings are not within 20 percent, notify higher level
(2) Place the operations switch (26, figure 2-7) on both
sets in the PARALLEL OPERATION position.
If the reverse power indicator (16)
Do not close the circuit breaker
of either set illuminates and the main
switch after starting the "on-
load contactor opens, open the main
coming" set as serious damage to
power switch and reparallel the
one or both generator sets may
When generator sets are being
operated in parallel, one or more
(4) Note the voltage indicated on the "on-line" set. Ad-
operators must remain with the sets
just the voltage of the "on-coming" set to the voltage noted
to monitor the rated load and current
on the "on-line" set.
(5) Adjust the frequency of the "on-coming" set to a
higher value that that of the "on-line" set.
Three generator sets can be operated
(6) Slowly reduce the frequency of the "on-coming"
in parallel. Paralleling procedures
are the same as those described
flash at 2 to 3 second intervals.
above. One generator set at a time
is brought on line.
Do not place the circuit breaker
switch of the "on-coming" set in the
Prior to removal of generator sets
CLOSE position while the SYN-
from parallel operation, make sure
CHRONIZING LIGHTS are lit as
the load does not exceed the full load
rating of generator set(s) remaining
damage to one or both generator sets