Appendix C
Heater Burnout Detection
70
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The total heater current during normal operation should not exceed 5 A. If the
current exceeds 5.5 A, a CT Input Overflow error occurs and
ffff
is displayed
if the heater current monitor is selected.
Measure each current with the heater current monitor. In some cases the calcu-
lated current may differ from the actual measured value.
Sample SV Calculations
Example 1
Using one 200 VAC, 800 W heater
Normal current = = 4 A
800
200
Burnout current = 0 A
SV = = 2 A (
≤
4.9 A)
4 + 0
2
Example 2
Using three 100 VAC, 100 W heaters
Normal current = x 3 = 3 A
100
100
SV = = 2.5 A (
≤
4.9 A)
3 + 2
2
Burnout current with one heater burned out = x 2 = 2 A
100
100
Difference between normal and burnout current = 3 – 2 = 1 A (
≤
0.5 A)
Specifications
Heater Burnout Detection Characteristics
Heater burnout detection setting range
0.1 to 4.9 A (in units of 0.1 A) (see note 1)
Current difference required for heater
burnout detection
0.5 A min. (normal time – burnout time)
Heater current monitor range
0.0 to 5.5 A
Monitor accuracy of input current
±
5% of FS
±
1 digit max.
Min. detectable ON time
200 ms (see note 2)
Note 1. If the heater burnout detection setting value is set to 0.0 or 5.0 A, no heater burnout detection is possible.
The alarm signal is turned OFF if the heater burnout detection setting value is set to 0.0 A and turned ON
if it is set to 5.0 A.
2. If the control output is turned ON for less than 200 ms, no heater burnout detection or heater current
measurement is possible.
E54-CT1/CT3 Current Transformer
Max. continuous heater current
50 A
Dielectric strength
1,000 VAC (1 min)
Vibration resistance
50 Hz (approx. 10G)
Weight
E54-CT1: approx. 11.5 g; E54-CT3: approx. 50 g
Accessories (E54-CT3 only)
Contact: 2; Plug: 2
electronic components distributor
