Of course, the ST hub has the option to have AA batteries for emergency power. But what will ST do without a router? Without an internet connection?
Sssuspect.
Even more so! ST hub does not transmit well-it receives Zigbee and Z-wave waves. The wall of AA batteries. Hmmmmm… Suspect.
ST hub & router requires an uninterrupted power supply. I’ll give it to them.
Computer UPS is not a good fit. It is designed for a high-power consumer. The No-load current will “eat up” more than the router itself and the ST hub.
I use an industrial UPS for security and fire alarm systems and video surveillance. Everything “industrial” is not beautiful, and does not have intelligence.
But it is not expensive, and it is easily modified (improved/upgrade).
I used a 24 volt UPS and added two DC-DC converters for 5 and 12 volts.
5 volts on the ST hub and 12 volts on the router.
Now we need to make this device “smart”.
Usually, this device has the simplest control functions - tamper switch opening and monitoring the availability of electricity in the network.
Tamper switch - this sensor not interested for me. I need to know about the power outage electrical networks… but the manufacturer made a simple sensor. He labeled it “KC”. The output of the “KC” - is the OPEN collector of the transistor, which is open as long as there is a 230V electrical network.
The manufacturer recommends connecting a relay to this “KC”,
but this does not work, because there is always a residual voltage on the contact - about 3 volts. The residual voltage does not allow the relay to switch off. In short - this schematic does not work.
In this situation, you need to use a comparator.
let’s set up the algorithm: there is no command up to 20V, there is a command from 20V to 24V.
The comparator will give a command to the relay.
Click-click-boom! Relay will open.
We will connect the door opening sensor to the relay.
The sensor will send a command to the ST hub.
The ST hub will inform you that there is no power supply in the network, everything is powered by an emergency power supply system.
Wow it wasn’t easy
Now we will know all events of our house.
