Omron EJ1 User Manual page 112

Detecting Current Errors
Normal Operation
17.3 A
200 V
200 V 17.3 A
200 V
To CT input
17.3 A
Heater Burnout Occurred
Burnout
Load: Heater
(example)
200 V
200 V 15 A
200 V
To CT input
15 A
To CT input
Current when there is a burnout
2. Three-phase Heaters
a. Delta Connection
Example: Using Three 200-VAC, 2-kW Heaters
Load
CT
CT
To CT input
When each phase's current is normal, the current is:
17.3 A ( ≅ × 10 A).
3
Load
CT
CT


3
= 10 A × ×
 
3 ------ -

 2
= 15 A
The heater burnout current when there is a burnout at the load line is as fol-
lows:
Heater burnout detection current =
The heater burnout current when there is a burnout at the load is as follows:
Heater burnout detection current =
To enable detection in either case, use 16.1 A as the heater burnout detection
current.
Load: Heater (example)
10 A
Load: Heater
(example)
200 V
200 V 17.3 A
200 V
To CT input
10 A
To CT input
Current when there is a burnout
17.3 + 15
------------------------
2
17.3 + 10
------------------------
2
Section 4-5
Burnout
Load
CT
CT

1
= 10 A × ×
------ -
3 
 3
= 10 A
≅ 16.15 [A]
≅ 13.65 [A]



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