How much power does a 1/2hp motor need to start ?

[phill d]

Hi guys
today I started up my generator to run my bench drill and a couple of lights in my garage.
But to my surprise the genny wont run the drill ???
now my generator is a Kawasaki GA1400 A and kicks out 240V & 115V 1200w MAX - 1050w.
so how come this drill wont run ?
when I push the start button the electric switch on the drill started clicking like a machine and
the motor just did not turn at all. its like it need a lot more power to click into start mode !!!
The drill is an Elliott progress no 1 with a 1/2hp hoover motor from new.
it states 230 -250 volts .....4.1 amps cycles 50..... wdg cap st (capacitor start I presume).
How much power would this need to get running ?
I use this generator to run 1,000 watt hand drill and a 1200 grinder no problem, also bench grinder is not a problem for it.
am I missing something here ? or is it something to do with capacitor start thing ?
I am no way too good on electrics (if I cant see it, I cant fix it ), so this has me a bit confused.
I thought 1/2hp would not be a problem with a 1200 w generator.


phill

 

[Wendelspanswick]

Has it got a contactor to start it, if it has it sounds like as you press the start button the contactor coil clicks in, the power goes to the motor windings which then cause a voltage drop on the contactor coil kicking the contacts back out.
You could try just a basic on off switch but that then removes the safety aspect of a NVR switch.

 

[phill d]

eeeerrrrrrrrrr mmmmmmmmmmm now if I ha d a clue as to what you mean I would probably tell you.
but what I do know is it has a capacitator on the back of the motor. the on off switch I think is original from when drill new (maybe not ).

maybe someone here knows what is what ? I wouldn't know the difference between NVR & QPR.
all I know is that on normal house electricity its perfect.
here is pic of switch and a pic showing it on the side of drill (don't know why pic is wrong way up)

 

[Digger6135]

Try removing the belt from the drill, and see if the motor starts, if it does not then it might be the centrifugal switch inside the motor. dropping out before the motor is up to speed ie, running on the run windings as opposed to the start windings, or it could be a failed capacitor.

Digger6135

 

[AdrianH]

Could you put a small, like 7 watt oven bulb or similar in the same circuit. If you see it dim when you hit the contactor then you are loosing volts.

Does that sound like a good idea?

Adrian

 

[rtbcomp]

Can you plug into the mains to check the motor.

NVR means "no volts release". Basically when you push the "Start" button an electromagnet holds the contacts to the motor closed. Pressing the "Stop" button releases the electromagnet and the motor is disconnected. The magnet will also drop out if the mains voltage fails, hence the term "no volts release."

If the genny voltage drops under the motor start-up load the elctromagnet could drop out. Keeping a finger on the "Start" button will call the electromagnet, and the cycle is repeated, hence the clicking.

 

[phill d]

while trying the drill I had a radio on and a 60 watt light bulb, the bulb did not dim and the radio stayed the same.
there was nothing at all at the drill motor making any noise, it was as if no power was getting past the on switch.
this switch don't do anything at all when no power is on, when power on it seems to click in and stay in a touch ?? then clicks when you press stop etc.
ill try it again tomorrow on both home electrics and the genny see what happens
I did try moving the belt to get motor moving but that made no difference at all, it still clicked like a machine gun with nothing at all at the motor, no buzzing neither.

could it be that it just needs a lot more power or a different hertz thing ? I don't know what the generator hertz is ???? the drill motor says 50hz
this is the plate on motor

 

[Justme]

1/2hp is less than 400 watts.

Yet at 4.1amps that plate suggest 943-984watts.

 

[rtbcomp]

"this switch don't do anything at all when no power is on, when power on it seems to click in and stay in a touch ?? then clicks when you press stop etc."

I explained that in post #6

 

[brightspark]

just take the front off the starter and bypass it . take supply cables live and neutral out and conect them direct to the motor leads . power it up for a few seconds if motor runs its a faulty contactor coil or burnt contacts .if it just hums its either a stuck centrifugal switch on the starting windings cap might be knacked thats if one is fitted

 

[rtbcomp]

Could there be an over-current device in the starter that's causing it to click off?

 

[Rudi McAnichal]

Presumably the drill runs OK from the mains. Can you borrow a clamp meter and measure the starting current?

I am guessing it is a standard squirrel-cage motor with direct-on-line starter, and without any soft-start device. Old rule of thumb was that starting current could be between three and six times the normal running current, so a 1kW generator may struggle to start the 1/2hp motor.

 

[phill d]

I will go down and check it today and im pretty sure its gonna be running fine on mains electricity, as it was running fine.
will try to see what voltage is coming from the genny incase that is not kicking out what it should be, i.e 230 -240 volts etc.
I do know the back of the switch looks a bit complicated, I will take some pics today.
(if I don't report back means ive touched something I shouldn't of and got electrocuted )


phill

 

[MattF]

Probably just your genny which is not upto the task. You'll know one way or the other when you try it on a fixed supply.

 

[rtbcomp]

If the genny was overloaded I'd expect his light to dim a bit and the genny slow down.

 

[MattF]

I'd expect to see or hear some indication too, but if it's kicking out extremely quickly, it's possibly just too quick to be of note. Besides, a lot of people don't have very discerning ears or eyes for minor faults. How many times have their been customers with switch modes screaming or tubes almost swamping one colour without them ever noticing, for example?

 

[phill d]

Well I put it on house electrics and it works. BUT sometimes I have to give it a shove ??? now this was not happening a few days back.
it did happen when I very first tried the drill then was fine for a few days.
But no clicking at all from the switch, it even dims the60 watt bulb when running from house electric when it starts then its all normal.
On the genny it just clicks like mad. I am thinking maybe the genny just aint kicking out what this needs to get the switch working ?
I am no electrician that's for sure.

Below is a pic of a diagram inside the switch box.. its well complicated I think..
you leccy blokes out there will probably know all about this.

.

 

[brightspark]

well its either the centifugal switch on the starting windings stuck open in the motor as was on mine. a quick bat with a hammer on the side freed it off and i squirted it with wd 40 and now its fine or the starting capacitor has gone thats if ones fitted

 

[phill d]

its got a long tube thing on back of the motor, I think that's a capacitor ? about 6 inch long and 2 inch diameter ish.
it don't need a bump start all the time, just now and then. I would say it needs a bump about 7 out of 10 times.
once its going its fine. I did clump it the other day and it did start ..
if its a dirty clutch thing ? what do I have to do to get at it and clean it properly ? is this something that can be got at easy...
I don't mind taking the motor off, as long as its not something I need a degree in science to do.
would a good blast of wd40 and an airline do any good ? would this be at the top by the pulley or the bottom of the motor ?

I am well impressed with the drill on the whole as I used it today for a project and everything was so easy compared to doing the same with a hand drill.



phill

 

[brightspark]

if theres a centrifugal switch fitted its inside the motor it would need the endplates taking off the switch is fitted on to the end plate and the sliding weights fitted to the comutator shaft dont just rive it apart