Hi folks,
unfortunately I need to raise a SAFETY ALERT on Shelly 2.5 devices, especially when operating in shutter mode. As for the nature of the fault, this problem can also occur in any other operating mode of the 2.5.
Fault Description:
- On of the two alternating contactors (in my case for OPEN direction) was sticking.
- Contactor provided continuous power to the OPEN output terminal
- Motor always moved upward until end microswitch switch stopped
- Fault not shown or detected by device
- Device Reboot and power cycle made no difference
Fault detection:
Shutter on command “close” went down 10cm.
As soon as the open end microswitch came out of his mechanical dead band, shutter stopped due to overpower (set to 180W).
In this moment, the motor was simultaneously powered for “open” and “close”, having two forces electrically and mechanicall work against each other.
Continuous power on “open” terminal made shutter open again.
Measurements to reveal this: Check with voltage meter on continuous power on one of the output terminals, irrespective of input switches or SW commands
Root cause:
Sticking contactor in Shelly 2.5, providing continuous power to one output, independently of actual control or commands.
Stuck contactor NOT detected by Shelly, power not measured, always reading “0 W”.
Operated shutter motor:
Nobily P4 13/14-40. 3-wire plus earth (open, close, neutral)
Nominal Power ~125W, way beyond the 10A / 2300W a Shelly 2.5 can handle per channel