Non- Invasive current sensor- Basic questions

Hello boys!

I am going to order a non-invasive current sensor but i dont know how to start. I was thinking of using this sensor:

https://www.sparkfun.com/products/11005( for my washing machine)

The current sensor will be used on a cable, meaning the voltage cable for the washing machine and my question to you is....

Do i need to order other components in order to get sensor data into my arduino ? Do i need to think about other factors before applying this sensor on the washing machine ? I just want to know how much current my washing machine draws.

Regards, Volkan

We were going to help you until you called us "boys"...

I just want to know how much current my washing machine draws.

Photograph the serial number plate with your cell phone and post it. Watts/voltage = current (A) Some washing machines run on 120vac , and some on 220vac . Yours ? What's the wattage rating on the plate ?

As said above, you could just look at it, and look at the specs online, unless you want measurements as compared to the various parts of a cycle.

Yes, you will need some form of signal conditioning coming off of it since it converts the current to a lower current. If you look at the datasheet, they use a 10OHm resistor which gives maybe 100mV output. You can work with this, but it might be easier to build an amplifier to boost the voltage up to 3V max (or 5V max, depends what you are running at, or you can do 1.1V and use the internal reference). Additionally, you need to make sure to clip this onto only 1 lead of the washing machine. It won't work clipped over multiple wires cables unless they are basically carrying the same current in the same direction (so 2 wires in parallel works, but not if one is the Live and one is the Neutral) This could get dangerous since it involves exposed/semi-exposed wires.

volkan163: Do i need to think about other factors before applying this sensor on the washing machine ?

Yes. You can't clip that over a mains cable because there's more than one cable running through it.

volkan163: I just want to know how much current my washing machine draws.

Get one of these: https://www.google.es/search?q=kill-a-watt&tbm=isch

A CT (current transformer) needs to clip over just the live lead (or just the neutral), so that it measures the actual current. Clipping it over both live and neutral will measure nothing since the sum of those currents is zero.

The most important thing to remember with a CT is that you must have a burden resistor securely connected to its secondary - if you don't highly dangerous voltages can be generated - so always go for a unit with a built-in burden resistor if you can.