User Manual

56
Using HBA and HS Alarms Section 3-10
3. V connecting lines: Refer to the following diagram for CT installation posi-
tions.
Note Heater voltage fluctuations are not considered here, so be take that
into account when setting the detection current.
3-10-3 Calculating Detection Current Values
• Calculate the set value using the following equation:
• To set the current for heater burnout when two or more heaters are con-
nected through the CT, use the value from when the heater with the small-
est current burns out. If all of the heaters have the same current, use the
value from when any one of them burns out.
• Make sure that the following conditions are satisfied:
Heater with a current of less than 10.0 A:
(Current value at normal operation)
− (Current value at heater burnout) ≥
1A
When the difference is less than 1 A, detection is unstable.
Heater with a current of 10.0 A or more:
(Current value at normal operation)
− (Current value at heater burnout) ≥
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 burnout and HS are not
detected when the set value is 0.0 or 50.0.
When the set value is 0.0, the heater burnout alarm is always OFF, and
the HS alarm is always ON.
When the set value is 50.0, the heater burnout alarm is always ON, and
the HS alarm is always OFF.
CT
CT
Load
Load
Load
Load (such as a heater)
AC line
Product
To CT input
Product
To CT input
CT
CT
Load
Load
Load (such as a heater)
AC line
Product
To CT input
Product
To CT in
p
ut
Heater Burnout Detection 1/2 set value =
Normal current value + Burnout current value
2
HS Alarm 1/2 set value =
Leakage current value (output OFF) + HS current value
2