Power Factor

You hear a lot about startup loads, peak loads, tools being loaded up even to the point they trip circuit breakers etc, so I was interested when I came across this inline meter, and being cheap thought it’d be interested in having a play.

Power Load Meter

Played just a little so far, seeing the air filter taking about 150W to start and get the motor up to speed, then settled down to just under 98W.  Given just how easy it is to overload circuits I will be interested in seeing how tools like the router have varying power draws based on load on the cutting operation.

Not sure what else I can, or will learn from this tool, but it will be interesting to experiment with it.

10 Responses

  1. I have one of these also and have been playing around with it on items in the house. I think I’ll have to give it a try in my shop. Don’t you think that you’re going to need a 2nd person to help read the numbers while you operate the router?

    • That’s what I’ll use a video camera for – specifically because I want the results for Stu’s Shed anyway, and means I can concentrate on the job at hand (an operating router for example) than being distracted by a power meter.

  2. start up loads of electric motors are typically 7 times running load, it has something to do with the EMF
    electro magnetic force

    • This meter isn’t responsive enough for that short initial spike, but as the motor is coming up to speed that is definitely observable, but not to those peak levels.

      I’m interested in startup more for where it can overload a circuit, and perhaps a comparison of a soft starting motor vs one that isn’t, the rest is very much monitoring running equipment and just how much can be put onto a circuit safely and so it doesn’t trip.

  3. I’d like to experiment with it too! Are you able to tell us where you got it and what it cost?

  4. Stuart,
    Steer away from the term POWER FACTOR it has a definite meaning in Electrical Engineering.
    Power Factor = Real Power/Reactive Power.
    I will not go any deeper for fear of scaring you “electron killer” types.
    Reference Terman p269 to 271

    • Hi Frank,

      Actually, do know about pf, all part of the electrical engineering components of my engineering degree.

      That the term had relevance to the topic was why I used it, and the device measures the power factor of the item plugged into it as well. Will be interesting in comparing how home appliances compare to industry, when (at least in NZ) businesses receive financial penalties if their pf drops below 0.95

      • Stuart,
        Jaycar says it will:
        “This intelligent power meter simply plugs into a normal power point (GPO) and turns it into a real-time power monitoring outlet. You can enter the local price of your electricity and the meter will tell you exactly how much the appliance is costing to run. In addition, the power meter tracks the power used and can display the instantaneous voltage or current being drawn as well as the peak levels that have been drawn. The meter has backup batteries so it will not lose the stored data during a blackout or moving from point to point. Simple to install and a valuable tool for monitoring you power consumption.”
        Not have the unit in my hand I could be wrong but I suspect it may not be able to measure Power Factor. If it does it is a very inexpensive meter.

        • Sounds like the one. There was also a 4 pack that wirelessly fed results back to a central monitor, but that was overkill for what I was looking to use it for.

          Top right corner has pf displayed as a %. Pretty neat unit all up!

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