Power limiter

A simple script that can alerts you if the current consumption exceeds a setted threshold. It gets the data directly from the ShellyEM meter and sends repeatedly alarm's messages to one or more telegram users.

Usage

The script is easy to use, but requires its configuration. Here are the steps that explain how to install and configure it.

1. Telegram Bot

To create the Bot just talk to BotFather and follow a few simple steps. Once you've created a bot and received your authorization token go to the next step.

2. Installation

Install the package by running the following command:

npm install -g power-limiter-shelly-em

3. Settings

In order to work the script needs a configuration file. It is provided a sample file that needs to be modified: config_sample.json

You need to provide the data to access the ShellEM web panel and set the channel you want to use to monitor the consumption (possible values are 1 or 2).

"shellyEM":{
		"username": "<username>",
		"password": "<password>",
		"host": "<ip-address--or--hostname>",
		"channel": "1"
	}

Here you can define:

• the max threshold (Watt);
• the time (seconds) in which the the current consumption must overcome the threshold before starting the alert;
• the time (milliseconds) between each repeated alarm's message.

"maxPower": 3300,
"timeBeforeAlert": 10,
"intervalAlertTime": 1500

Finally, you must provide the bot authorization token and the list of users that should be texted (true for receiving notifications and false otherwise). The pathToDB will be the path to a file used by the script to store users telegram's id.

"token": "<bot-authorization-token>",
"pathToDB": "/var/power-meter/db.json",
"notifyList": {
		"<username_1>": true,
		"<username_2>": false
	}

4. Run continuously

To start the script simple run:

power-limiter <path-to-your-config.json>

You may want to run it continuously in the background. To achieve this you can create a systemd service.

Create the file /etc/systemd/system/power-limiter.service and paste into it the followings lines:

[Unit]
Description=Power limiter
After=network-online.target

[Service]
Type=simple
ExecStart=/usr/bin/power-limiter <path-to-your-config.json>
Restart=on-failure
RestartSec=10
KillMode=process

[Install]
WantedBy=multi-user.target

Then, set the right permission by running chmod 644 /etc/systemd/system/power-limiter.service and start the service with systemctl start power-limiter.service and systemctl enable power-limiter.service

Now the script will always execute in the background.

Credits

Thanks goes to these wonderful packages:

• telebot
• simple-json-db
• console-stamp