TM 9-6115-669-13&P
1.13.2 Generator Operating Modes.
The EPP III contains two independent three-phase Generator Sets that can supply power to the RS
and ECS loads either individually or in parallel mode (figure 1-5a). If a commercial power converter
is also available, there is a further mode in which the KS and ECS loads can also be powered via the
commercial power converter, i.e. operating with a third generator as power converter (figure 1-5b).
In general it is possible to switch among all the modes without interruption at any time, once the
synchronizing devices have established voltage and frequency synchronization. Each generator can
individually supply all the power required for all loads.
1.13.3 Operating with one Generator.
The standard procedure is to operate with one generator set. In this mode, EPP III generator set 1
or 2 is operating. The generator set delivers 208V three-phase current at 400 Hz, at an output level
of 150 kW, by its power contactor K1. Power can be delivered immediately after the generator set is
turned on, although a few minutes of warmup time are generally allowed. Power is delivered and
distributed as shown in figure 1-5a, through a power distribution unit and bus bars. Prom there,
the RS load is powered through power contactors K3, K4, and K5 and three plug-in power cables
each approximately 95 ft (29 m) long. Power contactors K3 to K5 are used to distribute power over
three cables. A cable interlock loop also ensures that all three cables must be connected. The ECS
load is powered in the same way, through power contactor K6 and an additional power cable. A
control cable also runs to the ECS load, carrying control signals between the EPP III and ECS. The
ECS load can be operated individually, but the RS cannot, since the ECS contains the entire control
system for the load side.
1.13.4 Parallel Operation with Generator Sets 1 and 2.
A second generator set is brought on-line, with its power contactor K1, if one generator set either
fails or is being serviced. This mode can also be used for output distribution, i.e. each generator set
then operates at half its output. If one generator set fails, the second generator set automatically
produces full output. There is no interruption when switching between generator set 1, generator
set 2, and parallel mode.
1.13.5 Operating with Commercial Power Converter,
When a commercial power converter (figure 1-5b) is available, it is inserted between the EPP III
and the loads. The unit contains a converter that is supplied with 3x220 V, 50-60 Hz from the
external power grid. The converter (third generator) can also provide full power for the loads when
power contactor K40 switches converter voltages to the commercial power converter unit’s bus bars.
The procedure for switching over from the EPP III generator set to the commercial power converter
is as follows:
EPP III generator set 1 or 2, or both generator sets, are operating and supplying power for the
loads.
Commercial power converter is operating, but not on-line through K40.
Initiate synchronization by pressing button on EPP III PDU control panel.
When voltage and frequency synchronization has been achieved between commercial power
converter and EPP III generator set 1 and/or 2, power contactor K40 is switched into
converter bus bars.
EPP III then cuts off power from generator set 1 and/or 2. The generator set 1 and/or 2 is/are
now idling and can also be shut down.
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