Figure 5-6.--Two typical types of RTDs.
means a short circuit exists in either the RTD or
sensor increases, the resistance of the RTE also
its associated wiring. A very high reading, such
increases at a proportional value. All RTEs that
as 300F on a 0F to 300F RTD, could indicate
you encounter have a platinum element and have
an open circuit. You should compare these
an electrical resistance of 100 ohms at a
readings to local thermometers. This ensures that
temperature of 32F. Four different temperature
no abnormal conditions exist within the equip-
ranges of RTEs are commonly used, but you will
ment that the RTD serves.
find that the probe size varies. The four
If an RTD is faulty, you should replace it at
temperature ranges and their probe sizes are as
the earliest opportunity. Internal repairs cannot
follows:
be made to RTDs at the shipboard level. Until
you can replace the faulty RTD, you should
inform the watch standers that the RTD is
unreliable. The engine-room watch standers
should periodically take local readings to ensure
the equipment is operating normally.
Resistance Temperature Elements
The most common types of temperature
sensors you will find in gas turbine propulsion
plants are the RTEs. They operate on the same
You may find some RTEs that are connected
principle as the RTDs. As the temperature of the
to remote mounted signal conditioning modules.
5-5