TEMPERATURE MONITORING EXAMPLE
An IMR is installed as a monitoring device and back-up controller
for a freezer storage facility. Normally, the freezer temperature is
maintained at about -29°C ±2°. The absolute maximum allowable
temperature of the freezer is 0°C. In the event of a system failure, alarm
output #1 of the IMR is programmed to start a secondary cooling
system should the temperature reach 0°C. The additional alarm of the
IMR is used to signal personnel with a warning bell when the
temperature rises above -17°C
(indicating a possible failure of the
main cooling system)
. This alarm is programmed to latch in order to
assure that personnel inform maintenance of a possible problem. Key
switches are installed to lock out the front panel from unauthorized
personnel and to provide the means to reset the latched alarm. The
Integrator/totalizer option is specified to store peak and valley
temperatures overnight, weekly, etc. Programming module #5
(Pro 5)
is used to set up the integrator. The re-transmitted analog output is
specified to drive a chart recorder with 4-20 mA for a hard copy of
temperature profiles for later evaluation.
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