Rockwell Automation 900-TC32 Digital Temperature Controllers, Series B - Manual (Page 121)

Publication 900-UM007D-EN-E - January 2011
Configuration & Basic Operation 3-51
• The allowable controller heater current range is 0.1…49.9 A. Heater
burnout, HS, and heater overcurrent are not detected when the
configured alarm value is 0.0 or 50.0.
When the configured alarm value is 0.0, the Heater Burnout Alarm is
always OFF, the HS, and HO Alarm is always ON.
When the configured alarm value is 50.0, the Heater Burnout Alarm is
always ON, and the HS Alarm is always OFF, and the HOA is always
OFF.
• Configure the total current value for normal heater operation to 50 A or
less. When a current value of 55.0 A is exceeded,
ffff is displayed in
the Heater Current 1 (and 2) Value Monitor and Leakage Current 1 (and
2) Monitor parameters.
Application Examples
Single-Phase Heaters
EXAMPLE
Using a 200V AC, 1 kW Heater
The heater power supply provides 5 A when the current is normal, and 0 A
when there is a burnout.
Figure 3.99
Therefore, the heater burnout detection current is calculated as follows:
CT
0 A
200 V
CT
5 A →
←
5 A
200 V
Normal
AC line
Load Load
AC line
To CT Controller input To CT Controller input
Burnout
Load (such as a heater) Burnout
Heater burnout
detection current =
(Normal current) + (Heater burnout current)
2
=
5 + 0
2
= 2.5 [A]