Detecting Heater Overcurrent (4-Channel Models Only) - Omron G3ZA - MANUAL 2 User Manual

Detecting Heater Overcurrent (4-channel Models Only)

4-6

Detecting Heater Overcurrent (4-channel Models Only)

Setting Procedure
Heater Overcurrent
Detection Timing
Load current
(SSR output)
G3ZA output
G3ZA alarm
Note
Heater overcurrents are detected by determining whether the heater current is
above the heater overcurrent detection value when a G3ZA control output is
ON. The abnormal current detection delay can be set to prevent false overcur-
rent detection due to noise.
Make the following settings to detect heater overcurrent. If these settings are
not made, heater overcurrent may not be detected properly.
• Wire the CTs.
• Calculate the detection value that is appropriate for the application, and
set the heater overcurrent detection value.
• Set the abnormal current detection delay as described in 4-13 Setting the
Abnormal Current Detection Delay (4 and 8-channel Models)
page 52.
A
Note This example shows operation with the following settings:
Abnormal current detection delay = 0 (immediate alarm)
Operation at error = 0 (Continue with error clear)
• Heater overcurrent is detected at point 1 in the diagram above. The detec-
tion condition is as follows:
Heater ON current (see note 1) ≥ Heater overcurrent detection value.
• The heater overcurrent alarm is cleared at point 2 in the diagram above.
The clearing condition is as follows:
Heater ON current (see note 1) ≤ Heater overcurrent detection value −
Hysteresis (see note 2)
(1) The heater ON current is the peak load current that flows when the
G3ZA's output is ON.
(2) The hysteresis setting applies a dead zone between the detection condi-
tion and clearing condition, which prevents ON/OFF chattering of the
alarm. The same hysteresis setting is used for the heater burnout detec-
Section 4-6
V2
Hysteresis
Heater overcurrent
detection value
B
on
43