Heater Short Alarm (Hs Alarm) - Omron EJ1G User Manual

Detecting Current Errors
Normal operation
5-5-2

Heater Short Alarm (HS Alarm)

90
• The setting range is 0.1 to 99.9 A. Heater burnout is not detected when
the setting is 0.0 or 100.0. When the set value is 0.0, the HB alarm is
turned OFF. When the set value is 100.0 the HB alarm is turned ON.
• Set the total current value at normal heater operation to 100 A or less.
Examples
1. Single-phase Heaters
Example 1 Using a 200-VAC, 1-kW Heater
Normal operation
5 A
200 V
5 A
To CT input
The heater current is 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
Example 2 Using Three 200-VAC, 1-kW Heaters
15 A AC line
200 V Load
15 A
CT
To CT input
The heater current is 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:
Heater burnout detection current
The HS Alarm detection function measures the heater current when the con-
trol output (heating) is OFF. For details, refer to the following table.
(HS Alarm detection cannot be used with the control output for cooling.)
Control output (heating)
OFF
AC line
Load
CT
Normal current value + Burnout current value
=
5 + 0
= = 2.5 A
2
Heater burnout occurred
10 A
Load Load 200 V
10 A
To CT input
Normal current value + Burnout current value
=
15 + 10
=
2
Power to heater
Yes (HS alarm occurred)
No (Normal) (See note 1.)
Section 5-5
Heater burnout occurred
AC line
200 V
Burnout
0 A
CT
To CT input
2
AC line
Load Load
Burnout
CT
2
= 12.5 A
HS Alarm output
ON
OFF
Load
Load