Rockwell Automation 900-TC32 Digital Temperature Controllers, Series B User Manual
Page 123
Publication 900-UM007D-EN-E - January 2011
Configuration & Basic Operation
3-53
The heater burnout current when there is a burnout at the load is as follows:
(heater burnout detection current) = (17.3 + 10) / 2
≈ 13.65 [A]
To enable detection in either case, use 16.1 A as the heater burnout detection
current.
Figure 3.102 — Heater Burnout Detection
EXAMPLE
Using Three 200V AC, 2 kW Heaters, Star Connecting Lines
The current when each phase is normal is 5.8 A (
≈ 10 A × (1 /√3)).
Figure 3.103 — Star Connecting Lines
The heater burnout detection current for this connecting line is
5.4 A (= (5.8 + 5) / 2).
CT
CT
Load
Load
200 V
200 V
15 A
→
15 A
→
200 V
CT
CT
Load
Load
200 V
200 V
10 A
→
17.3 A
→
10 A
→
200 V
Burnout
Burnout
Burnout
Load
Load
To CT input
To CT input
Current when there is a burnout = 10 A
Ч
√
3
Ч
(
√
3/2) = 15 A
Current when there is a burnout = 10 A
Ч
√
3
Ч
(1/
√
3) = 10 A
Burnout
To CT Controller input
To CT Controller input
CT
CT
200 V
200 V
5.8 A
→
5.8 A
→
5.8 A
→
200 V
Load
Load
Load
Normal
To CT input
Load (such as a heater)
To CT Controller input