Figure 7-33.--SSPU local control (emergency) panel.
control panel also includes a master switch for
START/STOP/RUN operations and a dc circuit breaker.
Also located on the SSPU local control panel is an hour
meter to record the elapsed time the turbine has been
running. The start counter records the number of starts.
Figure 7-32.--SSPU control panel.
AC GENERATORS
Each SSPU drives its own ac generator. The two ac
exhaust gas temperature meter transducers and
generators driven by the SSPUs are brushless, 250-kVA
transmission lines. The panel lower section provides
units that produce 450-V ac, 400-Hz, 3-phase power.
switch controls to start, run, and stop both engines. This
Each generator consists of three machines (generators)
section also contains fault indicators that illuminate to
in one housing. Two of these machines are 3-phase
display the cause of the fault if an operating fault should
salient-pole synchronous units (alternators). The third
occur.
machine is a permanent-magnet, high-frequency (4,800
Hz at 8,000 rpm), single-phase unit that provides a low
Local Control Panel
power output used for initial excitation and control
circuits.
The SSPU local control panel is shown in figure
The main generator is a rotating-field unit that
7-33. The local control panel is located in the same space
develops the 400-Hz, 3-phase power supplied to the
as the SSPU and allows operation of the SSPU from that
location under emergency conditions. The SSPU local
output terminals. Excitation of the main field of the main
generator is received from the second 3-phase generator.
control panel includes a LOCAL/EOS switch. The local
The second 3-phase generator is an acting exciter that
operator can use this switch to select where SSPU
provides ac voltage. The ac voltage is rectified to dc
operational control will take place. The SSPU local
7-35
