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PRESYS
Instruments
5.0 - Calibrator Warning Messages
Warning
RAM ERROR
READ MANUAL
EEPROM ERROR
READ MANUAL
LOW BATTERY
UNDER / OVER
????.??ºC
6.0 - PID Control Parameters
The T-500PIR calibrators have a PID control algorithm to calculate the
temperature control output.
The black body cavity stability and response time features are related to the PID
parameters, explained below:
The K parameter (proportional gain) amplifies the error signal between the set
point and the cavity temperature to establish the output signal. When this parameter is
very high, the output reaction is very quick; however this can take the system into
oscillation. Decreasing this parameter, the cavity would not be able to react quickly
enough to external variations, giving the impression of a sudden out of control.
The I parameter (integral gain) is responsible for the integral action and it is the
most important part in the set point control. While an error persists between the set
point and the cavity temperature, the integral action will actuate on the output signal
until the error is brought to zero.
The D parameter (derivative gain) is responsible for the derivative action that
provides a quick response at the control output resulting from any rapt variation in the
cavity temperature. It is used to eliminate oscillations. However, it can cause
oscillations in the presence of much noise.
All temperature calibrators are tuned in factory and the parameters are close to
the optimum ones. In case one wants to improve a specific feature of the calibrator
(stabilization time or response time, for instance), make sure the alteration is made
reasonably.
Page 16
Meaning
Problem in RAM
memory
Problem in EEPROM
memory
Level of battery voltage is
low
Input signal out of
specifications or scaling
range
Input sensor is open
T-500PIR
Procedure
Turn the calibrator off and
on. If the error persists,
send the instrument to the
factory
Same as the previous item
Check the T-500PIR
calibrator power supply
See item 1.1.1 on Input
Specifications
Check input connections
and sensor
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