generator to power elec concrete mixer....

[JimK]

If I wanted to remotely power my ekec concrete mixer (850w), what size/capacity genny would I be best off with?

TIA

Jim K

[JimK]

Ekec = elec

Jim K

[harryagain]

You're probably cheaper to buy a petrol cement mixer. Though a generator is handy for other purposes too.

But a generator would need to be at least twice the size of the motor it was powering.

There can be problems with some generators as they don't do a proper sine wave which means the motor has to be de-rated, ie it may overheat if you fully load up your mixer. So watch the motor doesn't get unusually hot. Especially in hot weather.

[Dave Liquorice]

At the very least double 850 preferably 3 or 4 times so 2.5 kVA to 3 kVA.The waveform might not be ideal from a generator but it shouldn't be too bad from one with a continious rating 3 or 4 times that of the motor load.

Unless you have other uses for the genset, in which case 2.5 to 3 kVA is a good size to keep the freezers and CH on during a powercut, I'd look at hiring or buying a petrol mixer.

[Brian Gaff]

What is the starting current of the motor? Brian

[JimK]

How would I find that out?

Jim K

[John Rumm]

If its an induction motor (as most are) the current is likely in the range 5 to 9 times the nominal running current of the motor. You may find a marking on the motor giving a "Ia/In = 7.0" or something similar which tells you the ratio of maximum to nominal current.

Also keep in mind the motor will likely have a non unity power factor, and a genset will need to be able to supply the total current (real and reactive), not just the real component. So if you have the inrush ratio, multiply that by the VA rating of the motor rather than its real power rating.

[JimK]

thanks john

Petrol it is then :>)

Jim K

[John Rumm]

You *may* get away with it - since although the inrush is high, the start up time for a mixer is fairly short (if not full when you start it!) So you get a bit of extra inrush capability from the inertia of the spinning genset which will slow down as the mixer comes up to speed. As the mixer motor speeds up, its current draw falls.

[meow2222]

One can also put up with heavy voltage sag during start up, which in turn reduces current some. But there's a limit to how much a gen will tolerate.

NT

[Fredxxx]

The sag wouldn't worry me, it would be the breaker tripping that would cheese me off.

I like the idea of a electric mixer and a generator. Electric mixers are larger than genies and can then be run off electric when it's there. The gen can provide electric for when it isn't and for other uses as well.

It's economically viable as well.

[Fredxxx]

Might give you an idea.

Breakers can be fast acting and only take a modest overload before tripping.

Personally I wouldn't want to have one less than 2KVA rating though happy with a lower KW rating.

Most of the time it's going to be drawing a lot less than 850W. What does the rating plate and other spec say?

[Fredxxx]

What I tried to intimate is that it is more difficult to store a cement mixer, where generators are more compact.

[John Rumm]

A bit of lateral thinking would suggest a petrol mixer with built in genny might be good.

[meow2222]

I can imagine it shocking people as they chuck water in, and little kids riding in the drum when used unattended as a genny :)

NT

[meow2222]

There are some nice antique mixers with hit & miss engines

NT

[newshound]

+1

If you can afford it, consider an "inverter" one: better waveform, but also better and quieter motor.

I have the 1 kW one, it seems to be a reasonable clone of the Hondas which are nearly double the price. 4-Stroke, easy to start.