Limits for outputs

OUTPUT LIMIT

When configuring an output (relay) on THOR Digital Controllers the Limits page section will be presented. 

The Limits offers the ability to shut down a relay if it is running longer than desired. This can be a valuable safety tool in the event of a probe failure or if an error is made during programming. Probe failures can result in a setpoint never being attained resulting in a relay running continuously. 

During the programming sequence the Limits page section will be presented. The default for Limit is None meaning no limit will be enforced. There are two Frequency Limit options available:
1) Daily  - Run time from midnight to midnight
2) Hourly  - Run time during any single hour

To configure select the frequency (Daily is most common), next enter the Limit expressed as MINUTES.



When set to daily THOR will count minutes of operation during the 24 hour day. In the event the LIMIT in Minutes is reached the relay will be locked out for the balance of the current day. At midnight the counter will reset and the relay will be able to operate the next day up to the limit. 

In a similar fashion the Hourly option will count minutes (this value must be 59 or less) for each hour. In the event the Limit is reached during any hour the relay will be locked out for the balance of that hour. The timer will reset and repeat process at the top of each hour. 

HINT: Use the Analysis Tool for an output to determine the typical daily run time for the output. This is very useful in determining a LIMIT value for the target relay.

 

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