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1500°C Tube Furnace
Sensor Break & Loop Break Protection
Sensor Break Protection - The controller provides sensor break protection in the event the
thermocouple opens. If an open thermocouple condition occurs, the digital display will
blink "S.br", a red alarm beacon will be illuminated and the power to the heating element
will be shut off.
Loop Break alarm is displayed as CONTROL LOOP BROKEN. This occurs if the controller
does not detect a change in process value following a change in output demand after a
suitable delay time. Since the time of response will vary from process to process the Loop
Break Time parameter 'LBT' allows a time to be set before a loop break alarm is initiated.
In these circumstances the output power will drive to high or low limit. For a PID controller,
if the PV has not moved by 0.5 x Pb in the loop break time the loop is in break.
The loop break time is set by the AutoTune, a typical value is 12 x Td. The loop break
alarm may be disabled by setting its time to Off.
Over-Temperature Protection (OTP)
The over-temperature protection will be in effect during any alarm condition when the
temperature of the furnace has deviated beyond the limit. The Deviation High alarm is
triggered when the measured temperature becomes higher than the set point by the
amount of the threshold/deviation. Thermo Fisher recommends a value of 50°C above
your working temperature to provide protection for your workload.
In certain units, full scale high alarm 'Hi' is also present. Full scale high alarm will be
detected if the PV value exceeds the full alarm trip level.
To Configure Deviation High Alarm
1. Press SCROLL
button until "A1.DHi" appears on the display.
2. Press UP
or DOWN
We recommend a value of 50.
Main Controller: 5x16 Segment Programmable |
button to select the OTP value you desire.
Chapter 6
305435H03 | 6-37
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