Omron G3ZA - MANUAL 2 User Manual page 57

Detecting Heater Burnouts (4-channel Models Only)
Normal operation
15 A
200 V
To CT input
2. Three-phase Heaters
200 V
200 V
200 V
40
Example 2: Using Three 1-kW Heaters (200 V AC)
AC line
Load
15 A
CT
If the normal heater current is 15 A and the burnout heater current is 10 A, the
heater burnout detection value is calculated as follows:
Heater burnout detection value =
a. Delta Wiring
Example: Using Three 4-kW Heaters (200 V AC)
Normal Operation:
34.6 A
200 V
200 V 34.6 A
200 V
34.6 A
Each phase's normal current is 34.6 A.
× 20 A)
34.6 A (
3
Burnout Occurred:
Wire break
Load such
as a heater
30 A
CT
To CT
input
30 A
To CT
input
Burnout occurred
10 A
200 V
Load Load
10 A
To CT input
(Normal current + Burnout current)
15 + 10
=
2
Load
CT
To CT
input
CT
To CT
input
20 A
200 V
200 V
34.6 A
Load
200 V
CT 20 A
Section 4-5
AC line
Load Load
Wire
break
CT
2
= 12.5 A → 12 [A]
Load such
as a heater
Wire break
Load such
as a heater
Load
CT
To CT
input
CT
To CT
input
Load