Turbine Temperature and Speed
The SWBD 28-volt dc supply uses a bank of
Control Box
15 amp-hr lead-acid batteries for backup. This
battery bank allows starting of a GTGS when the
The turbine temperature and speed control
ship is without 450-volt ac power.
box (fig. 3-33, view B) is a combination electronic
speed switch and temperature amplifier. The box
The model 104 LOCOP electronics also
receives a speed signal from a magnetic pickup
include the turbine start/stop sequencing and the
on the PTO shaft and a temperature signal from
turbine temperature and speed control, which is
the turbine inlet thermocouples. These signals
enclosed in its own box.
position control relays in four speed channels and
five temperature channels within the box. They
also provide signals for local and remote
Turbine Start/Stop Sequencing
monitoring of speed and TIT. In combination
with logic circuitry described in the last section,
The turbine start/stop sequencing has seven
the four speed channels and five temperature
logic card assemblies. Each logic card assembly
channels provide the functions as described in the
performs a specific function. The functions of
following paragraphs.
these logic cards are as follows:
2200 RPM SPEED CHANNEL.--Energizes
Relay or solenoid drivers energize relays
(opens) the fuel shutdown valve and opens the fuel
or solenoids in response to a signal from
enrichment valve if fuel enrichment has been
a logic unit. They are used because the
selected. The fuel enrichment valve will be closed
relay and solenoid coils require more
again when the fuel manifold pressure reaches 50
current than can be supplied directly from
psig. The 2200 rpm speed channel also provides
a logic unit.
these functions:
Contact buffers minimize the effect of
Energizes the ignition system.
contact bounce (due to the operation of a
push button or relay contacts) on a logic
Closes the fuel manifold drain valve.
input.
Energizes the fuel pump paralleling valve
solenoid (closed) to place the fuel pump
The RTD signal conditioners convert
HP primary and secondary elements in
generator stator, air, lube oil, and bearing
parallel operation.
temperature to signals for local and remote
monitoring.
Positions the start limit control valve to
provide normal acceleration fuel flow.
The RTD temperature/pressure signal
However, the valve circuit remains armed,
conditioner converts engine enclosure
permitting the valve position to be con-
temperature and lube oil header pressure
trolled by the 1500F temperature channel.
to signals for local and remote monitoring.
Arms the fail-to-fire circuit, providing an
A set point card (1850F to 1870F)
automatic shutdown through the 600F
converts the TIT signal from the speed
temperature channel if 600F TIT is not
temperature control unit for control of the
reached within 10 seconds.
14th stage bleed air valve.
8400 RPM SPEED CHANNEL.--Provides
The vibration signal conditioner is a special
the following functions:
card. It is used to convert the signal from
a vibration pickup unit to a signal for local
Positions the paralleling valve to place the
and remote monitoring and alarm when
fuel pump in series operation.
vibration of the turbine occurs.
De-energizes the ignition system.
The remaining cards are logic cards for
Provides starter cutoff.
control, alarm, and alarm control.
3-48
