Rockwell Automation 900-TC32 Digital Temperature Controllers, Series B - Manual (Page 122)

Publication 900-UM007D-EN-E - January 2011
3-52 Configuration & Basic Operation
EXAMPLE
Using Three 200V AC, 1 kW Heaters
The heater power supply provides 15 A when the current is normal, and 10 A
when there is a burnout.
Figure 3.100 — Using Three 200V AZ, 1 kW Heaters
Therefore, the heater burnout detection current is calculated as follows:
EXAMPLE
Using Three-Phase Heaters, Delta Connecting Lines
The current when each phase is normal is 17.3 A (
≈ √3 × 10 A).
Figure 3.101 — Delta Connecting Lines
The heater burnout current when there is a burnout at the load line is as
follows: (heater burnout detection current) = (17.3 + 15) / 2
≈ 16.1 [A]
10 A
10 A
CT
15 A →
← 15 A
200 V
CT
200 V
Normal
To CT Controller input To CT Controller input
Burnout
Load Load Load
Load Load Load
Burn-
out
Heater burnout
detection current =
(Normal current) + (Heater burnout current)
2
=
15 + 10
2
= 12.5 [A]
CT
Load
Load
200 V
200 V
17.3 A
→
17.3 A →
17.3 A →
200 V
Normal
To CT input
Load
To CT Controller input