C Heater Burnout Detection - Omron C200H-TV Series Operation Manual

Heater Burnout Detection System
Heater Burnout Alarm Precautions
Determining the Heater Burnout Detection Current
Appendix C
Heater Burnout Detection
The heater wiring is connected through the Current Transformer (CT). As a cur-
rent flows through the heater wiring, an alternating current is induced in the CT
which is dependent on the size of the current flowing. This induced current drops
to zero if the heater burns out. The heater burnout alarm signal is output when
the induced current is compared to the set current value.
Turn on the heater power supply and the input terminal 24-VDC power supply
at the same time as or before the C200H PC power supply. The heater burnout
signal is output if the heater power supply or the input terminal 24-VDC power
supply is turned on after the C200H PC power supply.
Temperature Control Unit operation continues if a burned-out heater causes a
heater burnout alarm. Control signal output continues according to the control
parameters. Take measures to detect the heater burnout alarm signal to allow
early repair.
The heater burnout alarm is output when the control output is ON. Once the
heater burnout alarm is output, it remains ON. Use one of the methods below to
reset a heater burnout alarm.
1. Turn the Special I/O Unit Restart Flag (AR0100 to AR0109) ON and then
back OFF.
2. Turn the C200H PC power supply OFF then back ON.
3. Set the heater burnout current limit to 0.0 then back to its original value.
Make sure that the current difference between normal operation and heater
burnout is at least 2.5 A. Stable detection is difficult with a current difference
less than 2.5 A.
Heater burnout detection is not possible with the current output type (C200H-
TV 03) or with 3-phase heaters.
Set the heater burnout current to 0.0 when heater burnout detection is not re-
quired because the CT input wiring is not detected.
Determine the SV from the following equation:
Normal current value + heater burnout current
SV =
If more than one heater is connected through the CT, take the heater burnout
current as the value when the heater with the smallest current consumption is
burned out. If all heaters consume equal current, take the heater burnout cur-
rent as the value when any one heater is burned out.
Make sure that the current difference between normal operation and heater
burnout is at least 2.5 A. Stable detection is difficult with a current difference
less than 2.5 A.
Set the SV in the range between 0.1 A and 49.9 A. Heater burnout detection is
not carried out if the SV is set to 0.0 A or 50.0 A. The alarm signal is always OFF
if the SV is set to 0.0 or always ON if the SV is set to 50.0.
The total heater current during normal operation should not exceed 50 A. If the
current exceeds 55.0 A, a CT Input Overflow error occurs and ffff is dis-
played if the heater current monitor is selected.
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