Feature request: Over-Current triggers too quickly for slightly stuck valve

[Bob Stern]

@Ray: I appreciate the over-current limit feature you introduced in the last firmware update 8 months ago. I assume its intended purpose is to prevent damage caused by a short circuit. However, if you could delay its response time, it also would be useful to detect that an AC valve is stuck closed.

When an AC valve opens, the inductance of the solenoid increases because the ferrous actuator is pulled into the center of the solenoid, acting as a magnetic core. If the valve is stuck so that the actuator fails to retract, the inductive impedance of the solenoid will be lower, so the current will be higher.

For example, in my Netafim valves, the current draw is 135ma normally, but is 300ma when a valve is stuck closed. I have one valve that gets stuck once every few weeks, so it is useful for me to set an over-current notification for 250ma so that I can re-run the zone for that valve.

However, I find it’s common for other valves that are essentially good to have some friction so a valve can be stuck for half a second before it opens. Unfortunately, this triggers the over-current limit and unnecessarily halts that valve from running.

It would be helpful if you can change the over-current limit so that it triggers only after a certain time period. If the output of the controller is protected against a short circuit, then perhaps you could either implement a 1-second delay before triggering the over-current limit, or allow the user to set a custom delay.

Since detecting continuous over-current over a time period requires more programming than detecting it at a single point in time, perhaps you could simply delay the current detection until some delay time after a zone starts.

(Also, the documentation erroneously states that the imax value in the API is one-tenth the actual current limit. Actually, the imax value in the API is the actual current limit without any scale factor, except that only multiples of 10 are stored. Weirdly, the web interface only allows multiple of 50.)

Thanks!
Bob

[Author]

Posts