ARMY TM 9-6115-464-12
AIR FORCE TO 35C2-3-445-1
NAVY NAVFAC P-8-624-12
2-12 OPERATION OF TACTICAL UTILITY GENERATOR SETS.
a.
Parallel Operation (Load Sharing).
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
The first set started shall be designated as “on-line” and the sets in parallel operation shall be desig-
nated “on-coming”. With all sets shut down connect the load terminal boards as described in para-
graph 2-4e. Check that the voltage reconnection boards (paragraph 2-5) of the sets are identically
positioned.
Do not place the circuit breaker switch on any of the generator sets in the
CLOSE position until specifically directed to do so. Closing the circuit
breaker switch at any other time may severely damage one or more of the
generator sets. Equipment damage could result if caution is not observed.
Check that the main power switch (Figure 2-6) at the load is open before at-
tempting to place a generator set on line. Equipment damage could result
if caution is not observed.
Start the generator set as described in paragraph 2-6. Do not perform steps 7 & 8 of Figure 2-8.
Hold the CKT BRK switch (30, Figure 2-1) of the “on-line” set in the CLOSE position until the CKT
BRK indicator light (31) illuminates. Place the operation switch (26) in the PARALLEL position.
Set “Volt-Amps Transfer Switch (5, Figure 2-1) in the L1 -L0 position. Adjust the voltage adjust rheo-
stat (24) until the AC voltmeter indicates 122 volts for the 120/208 connection and 244 volts for the
240/41 6 connection. Adjust manual speed control (21) until the frequency meter indicates 61 Hertz.
Place the operation switch (26) of the “on-coming” set in the PARALLEL position.
NOTE
Observe the synchronizing lights of the “on-coming” set. The lights should go on
and off simultaneously. If the lights go on and off alternately, sets are out of phase.
Stop both sets and correct interconnect cables (Figure 2-5). If the problem per-
sists, refer to next higher level of maintenance.
Adjust the manual speed control of the “on-coming” set until the synchronizing lights (25), simulta-
neously, remain on or off at 2 to 3 second intetvals.
Carefully observe the synchronizing lights of the “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) illuminates, the sets are operating in parallel.
With no external load on the paralleled sets, adjust the manual speed control (21) of the “on-coming”
set until both percent power meters (kilowatt) indicate zero. Adjust the voltage adjust rheostat (24)
of the “on-coming” set until the percent of rated current meters (ammeters) on both sets indicate
zero. Turning counter clockwise will decrease readings.
Apply load to the sets. The kilowatt load should divide so that the load on each set is equal. If the
load and current are not shared equally, adjust the load by observing the set which has the higher
reading on the kilowatt meter (4). Decrease the engine speed of this set by adjusting counter cloc-
kwise the manual speed control (21 ) in small increments. Increase the engine speed of the set with
the lower kilowatt reading by adjusting clockwise the manual speed control in small increments. Ad-
justments should be made between both sets until the kilowatt meters are balanced.
The current should divide so that the observed difference 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 per-
cent, notify higher level maintenance.
2-21
