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Terminal Module
Considerations for TC
Measurements
38 Field Wiring
The isothermal characteristics of the HP E1415 Terminal Module are crucial
for good TC readings and can be affected by any of the following factors:
1. The clear plastic cover must be on the Terminal Module.
2. The thin white mylar thermal barrier must be inserted over the
Terminal Module connector (HP E1415 only). This prevents airflow
from the HP E1415 A/D Module into the Terminal Module.
3. The Terminal Module must also be in a fairly stable temperature
environment, and it is best to minimize the temperature gradient
between the HP E1415 module and the Terminal Module.
4. The VXI mainframe cooling fan filters must be clean and there
should be as much clear space in front of the fan intakes as possible.
5. Recirculating warm air inside a closed rack cabinet can cause a
problem if the Terminal Module is suspended into ambient air that is
significantly warmer or cooler. If the mainframe recess is mounted in
a rack with both front and rear doors, closing both doors helps keep
the entire HP E1415 at a uniform temperature. If there is no front
door, try opening the back door.
6. HP recommends that the cooling fan switch on the back of the of an
HP E1401 Mainframe is in the "High" position. The normal variable
speed cooling fan control can make the internal HP E1415 module
temperature cycle up and down, which affects the amplifiers with
these uV level signals.
Chapter 2
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