Omron E5AK PROGRAMMABLE TYPE User Manual page 86

CHAPTER 4 APPLIED OPERATION
J How to calculate
the heater burn-
out set value
4--24
• The heater burnout alarm function cannot be used when the heater is
controlled by a phase control system or by a cycle control system.
Also, the heater burnout alarm function cannot be applied on 3-phase
heaters.
To detect heater burnout on a 3-phase heater, use the K2CU-FjjA-jGS (with
gate input terminal). (For details, see the respective product catalog.)
• Calculate the set value by the following formula:
(current value at normal operation + current value at burnout)
Set value =
• Set the current value at burnout when two or more heaters are con-
nected to the CT to the value at the time that the heater having the
smaller(est) current value burns out (the value when one of the heat-
ers burns out with all heaters at the same current).
• Make sure that the following condition is satisfied:
Heater of current 10.0 A or less
Current value at normal operation - current value at heater
burnout ≧ 1A
When resultant current is less than 1 A, detection is unstable.
Heater of current 10.0 A minimum
Current value at normal operation - current value at heater
burnout ≧ 2.5 A
When resultant current is less than 2.5 A, detection is unstable.
• The set value can be set within the range 0.1 to 49.9 A. Heater burn-
out is not detected when the setting is "0.0" or "50.0". When the set-
ting is "0.0", the heater burnout alarm is set to "OFF," and when the
setting is "50.0", the heater burnout alarm is set to "ON."
• Set the total current value at normal heater operation to 50 A or less.
When set to 55.0 A minimum, [
rent monitor" parameter.
2
] is displayed in the "heater cur-