User Manual

57
Using HBA and HS Alarms Section 3-10
• 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 (and 2) value monitor” and “leakage current 1 (and 2)
monitor” 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
AC line
Load Load
AC line
Product
To CT in
p
ut
Product
To CT input
Burnout
Load (such as a heater)
Burnout
Heater burnout detection current =
(Normal current) + (Heater burnout current)
2
=
5 + 0
2
= 2.5 [A]
10 A
10 A
CT
15 A→
←15 A
200 V
CT
200 V
Normal
Product
To CT input
Product
To CT in
p
ut
Burnout
Load LoadLoad
Load LoadLoad
Burn-
out
Heater burnout detection current =
(Normal current) + (Heater burnout current)
2
=
15 + 10
2
= 12.5 [A]