Omron G3ZA - MANUAL 2 User Manual page 64

Detecting SSR Short-Circuits (4-channel Models Only)
Note
1,2,3...
Precautions
Operation after Error
Detection
Calculating the SSR
Short-Circuit
Detection Value
Setting Ranges Supported in the
The current range and units are determined by the Current Monitor Selector
setting.
Variable type Parameter name
83/C3 Current Monitor Selector
Detection values of 0 to 165 (A or %) max. can be detected, but set the detec-
tion value appropriate for the current range. If the detection value is set above
the current range, errors will not be detected. Refer to 4-3 Selecting the CT (4-
channel Models Only)
V2
Example: Setting the CT1 SSR short-circuit detection value to 20 A
1. Set the CT1 SSR short-circuit detection value to 20 with a Variable Area
Write command.
2. The current is detected in CT1, and SSR short-circuits are detected with
the timing shown in the diagram on the preceding page.
3. Once the CT1 SSR short-circuit detection value is written, the setting is
saved, and will also be effective the next time that the power is turned ON.
The actual current flowing in the heater may not be the same as the heater's
rated current. Check the heater current under actual conditions using the CT1
to CT4 Heater OFF currents.
It is possible to select the Controller's operation after an SSR short-circuit is
detected.
For details on selecting operation after an error, refer to 4-14 Setting Opera-
tion at Error (4 and 8-channel Models) on page 53.
When an SSR short-circuit has been detected, it is possible that the SSR has
failed in the always-ON state so that it cannot control operation. Consider
installing a failsafe circuit to cut off the power supply to the heater.
Set an SSR short-circuit detection value appropriate for the customer's appli-
cation.
As a rule, set a detection value that is at least two times the normal heater
OFF current. Proper detection may not be possible if a value that is less than
two times the normal heater OFF current is set. In additions, short-circuit
detection value is set to 0 A, so set a detection value of at least 1 A.
V2
Models (0 to 165 A, or %)
Setting
0 0 to 55
1 0 to 165
2 0 to 110
on page 33 for details on detection values.
Section 4-7
Current range Units
A
A
%
47