Example – Rockwell Automation 900-TC32 Digital Temperature Controllers, Series B User Manual
Page 124
Publication 900-UM007D-EN-E - January 2011
3-54
Configuration & Basic Operation
Figure 3.104 — Heater Burnout Detection
EXAMPLE
Using Two 200V AC, 2 kW Heaters, V Connecting Lines
Figure 3.105 — V Connecting Lines
The heater burnout current when there is a burnout at the common is as
follows:
Heater burnout detection current = (10 + 5) / 2
≈ 7.5 [A]
The heater burnout current when there is a burnout at the load is as follows:
Heater burnout detection current = (10 + 0) / 2
≈ 5 [A]
To enable detection in either case, use 7.5 A as the heater burnout detection
current.
CT
CT
200 V
200 V
5 A
→
5 A
→
200 V
Load
Load
CT
CT
200 V
200 V
5 A
→
5 A
→
200 V
Load
Load
Burnout
Burnout
Load (such as a heater)
Load (such as a heater)
Load
Load
To CT input
To CT input
Burnout
Current when there is a burnout = 10 A
Ч
(1/
√
3)
Ч
(
√
3/2) = 5 A
Current when there is a burnout = 10 A
Ч
(1/
√
3)
Ч
(
√
3/2) = 5 A
To CT Controller input
To CT Controller input
CT
CT
Load
200 V
10 A
10 A
→
17.3 A
→
200 V
200 V
Load
Normal
To CT input
To CT Controller input