92
Detecting Current Errors Section 4-5
b. Star Connection
Example: Using Three 200-VAC, 2-kW Heaters
When each phase's current is normal, the current is: 5.8 A
≅ 10 A × .
With this configuration, the heater burnout detection current is as follows:
Heater burnout detection current = = 5.4 [A]
Normal Operation
CT
To CT input
To CT input
Load
Load
Load
5.8 A
200 V
200 V
5.8 A
5.8 A
200 V
CT
Load: Heater (example)
1
3
-------
Heater Burnout Occurred
CT
To CT input
To CT input
Load
Load
Load
200 V
200 V
5 A
200 V
5 A
Burnout
CT
To CT input
To CT input
Load
Load
Load
200 V
200 V
5 A
200 V
5 A
Burnout
CT CT
Load: Heater
(example)
Load: Heater
(example)
Current when there is a burnout = 10 A × ×
= 5 A
1
3
-------
3
2
-------
Current when there is a burnout = 10 A × ×
= 5 A
1
3
-------
3
2
-------
5.8 5+
2
------------------
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