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Using Heater Burnout, Heater Short, and Heater Overcurrent Alarms Section 3-10
• 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, HS, and heater over-
current 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, the HS alarm is
always ON, and the heater overcurrent alarm is always ON. When the set
value is 50.0, the heater burnout alarm is always ON, the HS alarm is
always OFF, and the heater overcurrent 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) Moni-
tor parameters.
3-10-4 Application Examples
Single-phase Heaters Example: Using a 200-VAC, 1-kW Heater
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:
Example: Using Three 200-VAC, 1-kW Heaters
The heater power supply provides 15 A when the current is normal, and 10 A
when there is a burnout, so the heater burnout detection current is calculated
as follows:
CT
0 A
200 V
CT
5 A→
←5 A
200 V
Normal
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