TM 9-6115-669-13&P
1.14.3 Controlling Operation with Commercial Power Converter.
Five cases can exist when operating with the commercial power converter (figure 1-6):
Case 1:
EPP III connected by commercial power converter; EPP III providing power to loads;
changeover to generator 1 or 2.
Case 2:
EPP III connected by commercial power converter; commercial power converter providing
power to loads; changeover to generator 1.
Case 3:
EPP III connected by commercial power converter; EPP III providing power to loads;
commercial power converter shut down.
Case 4:
EPP III connected by commercial power converter; commercial power converter providing
power to loads; EPP III shut down.
Case 5:
Commercial power converter providing power to loads; EPP III not connected.
Case 1: EPP III connected by commercial power converter; EPP III providing power to
loads; changeover to generator 1 or 2.
1.
Relay K21 (figure 1-10) is energized, because EPP III is providing power to the loads.
This relay detects the presence of phase voltages on the EPP III bus bars.
2. Relay K20 detects the presence of commercial power converter phase voltages
(the commercial power converter has not yet been switched into its bus bars).
3. Pressing PARALLEL OPERATION ON illuminated pushbutton switch S2 on the EPP III PDU
control panel energizes relay K12, which latches by contact 34/33. At the same time,
PARALLEL OPERATION ON lamp H10 lights up on the control panel. Relay contact 13/14 of
K12 closes, initiating evaluation of synchronization between EPP III and commercial power
converter (paragraph 1.14.2). PDU electronics group N6 checks the conditions below and
switches time relay K13 when the two systems are synchronized.
4. Time relay K13 delivers a 0.6 seconds activation pulse, by its contact 15/16, to relay K15 when
the following conditions are met:
ECS and/or RS loads activated, relay contact 33/34 of K10 and/or 13/14 of K11 closed.
Commercial power converter delivering voltage; contact 13/14 of K20 closed.
Generator delivering voltage (i.e. power); contact 21/22 of K21 open.
Synchronization assured since time relay K13 is active.
Relay contact 16/15 of K14 closed.
When relay K16 is energized, generator changeover occurs as follows:
1.
Relay K16 latches by contact 5/6.
2.
Contact 21/22 of K16 opens, causing relay K12 to de-energize; PARALLEL OPERATION ON
lamp H10 on control panel goes out. PARALLEL OPERATION lamp H9 goes on, since contact
13/14 of K15 closes.
3. Contact 1/2 of K15 activates power contactor K40 in the commercial power converter, by
connector pin J20-A/B, so that the commercial power converter is now additionally switched
onto the bus bars, i.e. the loads. Connector pin J20-C/D provides the minus terminal for K40.
4.
Contact 3/4 of K15 closes, issuing a shutdown command to generator 1 or 2. The generator
disconnects from the bus bars of the EPP III, and runs at idle.
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