Ask The Trades - Print Page

Ask The Trades
https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> How to start an electrical motor https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1433909861 Message started by Fabricius on Jun 10^th, 2015, 5:17am

Title: How to start an electrical motor
Post by Fabricius on Jun 10^th, 2015, 5:17am

HI.

How to start a motor?

Sounds weird, right!

Well, I found out that you can produce electricity by rotating the shaft on a motor, I'm talking about, in this case, a microwave plate motor.

I heard about it on YouTube, so I grabbed the chance and unmounted our microwave oven which was broken anyway, so my wife didn't get upset.

Lo and behold, I was able to produce 380V by turning the shaft/axle fast enough, and I was able to light a light bulb.

Very cool indeed, since I'm new to that kind of stuff, but I ran into a problem.

Even though I'm able to generate 120v, 240v or even 380v I'm not able to start an electrical motor, like a blender/mixer or a ventilator/fan, why is that?

I'm able to turn on a light bulb, a led, and even the electric spark to turn on the stove, but anything that has a motor on it won't start.

Even one of those little tiny motors, that runs on a 1.5 AA battery didn't run.

So my question is, how do I, by producing my own energy/electricity, make an electrical motor run.

Thank you,

:)

Fabricius

Title: Re: How to start an electrical motor
Post by Lectrician on Jun 10^th, 2015, 3:08pm

You need a good kick of current to start a motor. It presents essentially a near short circuit to the supply until it starts to run (when the back emf then chokes the current and causes it to lag). Your generator (the microwave motor) just doesn't have enough poke to allow this. Small resistive loads would be OK, but not, as you've found, inductive loads.

Remember also, your motor running as a generator may be able to produce volts, but not stable. You need a good steady voltage output. The motor is unlikely to be able to support anything other than very low current items.

Title: Re: How to start an electrical motor
Post by big_all on Jun 11^th, 2015, 5:25pm

you need to understand the input energy from "generator" required to operate the drive motor will be far greater than the motor output
in other words no free energy if your turning it manually cranking what ever the motor drives directly will be far more efficient with virtually no losses in transmission

Title: Re: How to start an electrical motor
Post by thescruff on Jun 11^th, 2015, 9:54pm

big_all wrote on Jun 11^th, 2015, 5:25pm:

You missed a calculation BA ::)

If a unit of electricity costs 20p and it costs you 10p to produce 1 unit then you are 50% better off 8-)

And if you ask gov.con, they'll chuck in another 30p per unit for saving the planet. ;D

Title: Re: How to start an electrical motor
Post by big_all on Jun 12^th, 2015, 11:30am

at least the pay in tariff has been halved ::)