Calculating Detection Current Values; Application Examples - Omron E5C User Manual

4-12-4 Calculating Detection Current Values

Calculate the set value using the following equation:
Heater Burnout Detection 1/2 set value = Normal current value + Burnout current value
HS Alarm 1/2 set value = Leakage current value (output OFF) + HS current value
• To set the current for heater burnout when two or more heaters are connected through the CT, use
the value from when the heater with the smallest current burns out. If all of the heaters have the same
current, use the value from when any one of them burns out.
Example: Set value of Heater Burnout Detection 1 or 2 parameter = (Normal current value × Number
of loops + Burnout current value)/2
• Make sure that the following conditions are satisfied:
Heater with a current of less than 10.0 A:
(Normal current value) − (Burnout current value) ≥ 1 A
When the difference is less than 1 A, detection is unstable.
Heater with a current of 10.0 A or more:
(Normal current value) − (Burnout current value) ≥ 2.5 A
When the difference is less than 2.5 A, detection is unstable.
• The setting range is 0.1 to 49.9 A. Heater burnouts and heater shorts are not detected when the set
value is 0.0 or 50.0. When the set value is 0.0, the HB alarm is always OFF and the HS alarm is
always ON. When the set value is 50.0, the HB alarm is always ON and the HS alarm is always OFF.
• Set the total current value for normal heater operation to 50 A or less. When a current value of 55.0 A
is exceeded, ffff is displayed in the Heater Current 1 (or 2) Value Monitor and Leakage Current 1
(or 2) Monitor parameters.

4-12-5 Application Examples

(1) Single-phase Heaters
Example: Using a 200-VAC, 1-kW Heater
Normal
The heater power supply provides 5 A when the current is normal, and 0 A when there is a
burnout, so the heater burnout detection current is calculated as follows:
Heater burnout detection current =
5 + 0
=
E5@C Digital Temperature Controllers User's Manual (H174)
AC line
5 A
Load
200 V
5 A
CT
Product
To CT input
= 2.5 [A]
2
2
2
Burnout
200 V
Burnout
0 A
Product
To CT input
(Normal current) + (Heater burnout current)
2
4 Basic Operation
AC line
Load
Load (such as a heater)
CT
4 - 45
4