Is it the heater or the sensor?

When they get this kind of problem, how do they know if the heater is bust,
and not just the temp sensor which is measuring it?

Brian



--
Brian Gaff....Note, this account does not accept Bcc: email.
graphics are great, but the blind can't hear them
Email:
__________________________________________________ __________________________________________________ __________

Brian Gaff wrote:
When they get this kind of problem, how do they know if the heater is bust,
and not just the temp sensor which is measuring it?

Brian

I guess at first they don't know what is causing the problem.

From memory last night on NASA TV they said they noticed the sensor was
reporting 80 something degrees when it should've been over 100, then
they found out that the heater itself had failed.

Simon Howson

On Sun, 02 Jul 2006 06:18:24 GMT, "Brian Gaff"
wrote:

When they get this kind of problem, how do they know if the heater is bust,
and not just the temp sensor which is measuring it?

Just a general electrical engineering comment.

Typically the current in a particular circuit or groups of circuits will be
monitored and included in the telemetry. Heaters take considerable power
and thus a fair amount of current so any break in the heater or wires or
connections that result in an open would be diagnosible, assuming sufficient
resolution in the current measurement. The amount of current for a
temperature sensor is quite low. One popular temperature sensor will use 1
uA per degree K, for example.

--
rk
--
rk, Just an OldEngineer
"The number of people having any connection with the project must be
restricted in an almost vicious manner. Use a small number of good people."
-- Kelly Johnson in Skunk Works