Standby Generator doubt!

[LijoeThomas]

I was thinking of making a standby generator.
My doubt basically is if a gnerator capable of 1KVA is connected to a motor, and if my appliance which is the load requires only 25W of power to work, how do i get rid of or dis-allocate the rest of the power?

 

[Nigel Goodwin]

You don't, it's like a battery in that respect, the load takes what it needs - the generator will auto-adjust itself to keep the voltage output fairly constant, by adjusting the throttle on the engine. My Brigs Stratton 2KVA generator (which I can't persuade to start!) uses the normal crude system - the exhaust gases blow against a 'paddle' which is connected to the throttle control.

I've used it to power a microwave oven, and as the oven turns OFF and pings, there's a sudden large burst of revs before it can throttle back down.

I've got it permanently wired in an out-building (old outside toilet) and connected back to my fuse box in the house via a changeover relay, as the generator runs the relay switches over from mains to generator power - but ONLY for one specific fusebox, this feeds the house lights, the sockets in the kitchen where the microwave is, and the sockets for the TV and stereo

I actually bought and wired it after a VERY bad winter in 1990, my daughter was only a couple of months old, and we had no electricity, no water, and no phone for ten days - luckily our neighbour has a gas cooker, so she melted snow to make up the bottles for Melissa. It's never happened again since, but I have run the generator a couple of times for short term power cuts (usually some idiot in a digger having gone through the cables somewhere!).

 

[JimB]

My Brigs Stratton 2KVA generator (which I can't persuade to start!)

Try draining out all the old petrol, thoroughly cleaning the carburetter and using new petrol.
I have no direct experience, but I have heard that petrol can "go off" if left standing for months/years.

JimB

 

[Nigel Goodwin]

Try draining out all the old petrol, thoroughly cleaning the carburetter and using new petrol.
I have no direct experience, but I have heard that petrol can "go off" if left standing for months/years.

I left it empty since I'd previously used it, and it looks a pain to get the carburettor to pieces It's been left with petrol in it now for a while, since I last tried to start it.

The spark actually seems quite weak, but it uses the usual horrible batteryless ignition system. One day I might get down and have a real try at it!.

 

[oldtimer]

I had a 1.2 Kva genny on my Catamaran it had this arcaic spring system to control the varying loads but I changed it to electronic. You simply monitor the frequency since a heavy load will try to stall it and therefore the frequency drops and vicky verky. I will leave you to figure out how to control the throttle since your ideas may be better than mine.

 

[bryan1]

Hiya Nigel,
Eh mate grab a can of aerostart (that about 33% ether) and spray some in the air intake and see if the motor will start. If not then it could be water in the fuel system or the valves are choked up with gunk. My 5.8kva genny I have as a backup for my house solar array was running dead rough and sure enough water in the fuel was the problem and this genny is less than 3 years old has has only done about 100 hours running. B&S motors are loved by some and loathed by most but I've never had any trouble with my backup B&S water pump. I ran it last weekend after 12 months with the old fuel and it started 2nd pull . Anyway it might pay to take the genny down to a local small engine mechanic and get him to check it out.

Cheers Bryan

 

[oldtimer]

2 strokes are very fussy about petrol/oil ratios. If it's 4 stroke the fuel system is usually at fault, jets getting clogged,don't use wire to clear them use air,also the air filter needs looking at some have wire mesh soaked in oil,give it a good clean. Make sure the gaskets don't leak round the carb. clean out the fuel tank and lines.

 

[john1]

Hi,

The Briggs and Stratton is usually a four stroke, i haven't met a two
stroke Briggs and Stratton, although i see no reason to think there
aren't any.

The magneto type of ignition system is really surprisingly reliable
in my opinion. There are two basic arrangements, the contact-less
type called 'Electronic' and the older more traditional points type.

Only physical deterioration or damage is likely to prevent the
electronic type from working, sometimes damp may have to be cleared
and once cleared should not prevent the ignition system from working
assuming there is no damage or excessive deterioration to the lead or
the cap and plug.

With the points type there are two common reasons for failure. One is
corrosion on the contact surfaces, these can be accessed via a hatch
or cover on the flywheel and cleaned. Two, the moving contact can get
stiff, and not move properly, sometimes staying open. Just check that
its free like its supposed to be.

Another problem that crops up occasionally is that the inlet valve can
get stuck open, or sometimes not close properly. this is usually due
to rust on the valve stem making it stiff. The cam will lift it, but
its the spring that has to return it. You would think that a bit of
rust would soon clear with the valve going up and down, but it doesn't
always clear, sometimes it sort of gets 'impacted' and requires actual
intervention to free it. A finger on the plug-hole will tell you if
there is compression when the engine is turned, but keep the lead out
of the way. Curiously i have never met this problem with the exhaust
valve. Dunno why not, either of them could be left exposed to the air.

I usually check for ignition by spark length from the end of the lead
to the engine block, i expect about three eighths of an inch to be
about right, it may run with a lesser spark, but if you cant get more
than an eighth of an inch then theres something wrong there.

I dont find plug gap critical, about my thumnail thickness seems right
to me.

PETROL.
As has been mentioned, petrol does deteriorate. Try to use very fresh
petrol if you get problems starting after a period of inactivity. I've
never had problems with older petrol after starting with fresh petrol,
but often they wont start using petrol thats been sitting around for
a few months.

Some small engines use a spark killing method which is operated by the
oil condition. Especially on generators which may get run for long
periods without the oil getting checked, this is one way of getting
the oil changed if it becomes so grotty that the extra wire from the
magneto kills the spark. This arrangement may have prolonged the life
of many small engines, although i have never seen it used on a Briggs
and Stratton, but you never know. Of course once you know about it,
the wire could just be lifted, but thats a bit of a liberty.

The most usual cause of problems is water in the fuel, or in the
carburetter, and even after clearing the water, theres the corrosion
which can block jets, and needs cleaning out. Ive always been happy
to use bits of wire although some say you should only use compressed
air. I use compressed air too, but sometimes thats not enough, and a
bit of wire will usually clear out a stubborn jet.

Best of luck with it,
John

 

[mramos1]

I left it empty since I'd previously used it, and it looks a pain to get the carburettor to pieces It's been left with petrol in it now for a while, since I last tried to start it.

The spark actually seems quite weak, but it uses the usual horrible batteryless ignition system. One day I might get down and have a real try at it!.

First thing to try..

Get stabil (called here in the states, gas treament), some spray starting fluid and spray carb cleaner. Pour stabil in the tank with new gas (read the label for amounts of stabil). Take off the air filter and spray carb cleaner in the carb. Let it sit a couple days.

After a day or two, take off the air filter again, flip all things to ON, spray "starting fluid" in the carb and crank.. It will fire and run a bit, probably die.. Do that a couple (or many times) to suck all the junk out.. I have done this before, and this is on things that have sat year or so maybe.
You can use something call (I think it is JB "blast") as well to replace the carb cleaner.

If more than a year of sitting, a mechanic friend takes off the carb and soaks it in mineral spirits for a few hours. Then sprays it with carb cleaner. Then back on the motor, "starting fluid" trick above.

I Florida, we have toys and generators. I have lots of items that sit a year or more (presure cleaner, generators, dirt bikes, go-karts, RV, boat, etc). And when you put it away, add stabil to the gas and you can leave it in the tank for 1.5 years and it will crank when you crank it. I still close off the fuel and run that gas out, but I leave it in the tank.

Never thought I would be leaving this post on electro-tech.

PS: Or new carb from Ebay..

 

[Nigel Goodwin]

I can't believe all the enthusiasm and suggestions for starting small engines?

I must admit, years ago as a kid, we used to always be using 'Easy Start' to get things started - an aerosol you squirt in the carb, in fact we even used to use it for testing glow plug engines, no fuel tank, just a quick squirt in the air intake and they will run for a few seconds.

After all this help I can see I'll have to dig it out and have a look at it!, getting a can of something to spray in it.

Thanks everyone for all the suggestions!.

 

[Hero999]

The speed is kept constant to keep the frequency the same. When a larger load is applied the regulator increases the field coil current hence increasing the torque or mechanical lod on the engine, so the govenor pulls on the throttle slightly keeping the speed constant.

 

[Arctic Fox]

Interesting...

We're sitting in an Alternative Energy forum and talking about using gasoline.




Power that bad-boy with corn!

E-85

 

[Sig239]

If more than a year of sitting, a mechanic friend takes off the carb and soaks it in mineral spirits for a few hours. Then sprays it with carb cleaner. Then back on the motor, "starting fluid" trick above.

It should be noted that during this task you will also need to replace the bowl gasket, needle valve, and valve seat as the mineral spirits will damage the valve seat. This can be bought in kit form fairly cheap. Do not use anything metal to remove the valve seat(any small scratches may prevent the valve seat from seating properly). A shot of compressed air will remove it easily. This may sound like a lot to do, but really it is very simple, and is considered rebuilding the carb. Works like a charm.

 

[mramos1]

It should be noted that during this task you will also need to replace the bowl gasket, needle valve, and valve seat as the mineral spirits will damage the valve seat. This can be bought in kit form fairly cheap. Do not use anything metal to remove the valve seat(any small scratches may prevent the valve seat from seating properly). A shot of compressed air will remove it easily. This may sound like a lot to do, but really it is very simple, and is considered rebuilding the carb. Works like a charm.

Good point, remove the carb, take it apart, drop the metal parts in mineral spirits, then re-assemble. That is probably a good time to replace the gaskets and O-rings if needed.

I have always used the way I said I did it and it has worked, but a friend that does it for a living mentioned the other..

Atric Fox:

You are right. But I think of Energy as mains power to my house as well, and if I have no power, the petrol generator works for me as an alternate way of getting it.

 

[bristol188]

This is electronic but still to do with small gas. engines. Solid state ing. (module)s are most times secificly designed to not produce a spark when
the engine is turned slowy (safety resons) So be awear when testing for spark.

 

[XHoosier]

Alternate Energy New Project

Hi Guys,

I am new to this forum, and have a very interesting project to do. I want to use a 5 KW AC single phase generator, with a 3 KW AC output, thru an adequately sized full bridge rectifier, into a Pi Filter network of a 600 VDC Capacitor, thru a filter choke, then another 600 VDC capacitor, a bleeder resistor across the DC output, and then run the DC into a Grid Tie Inverter. I don't know how to size the capacitors capacitance wise, or the filter choke impedance. Does anyone know how I can calculate these values? The generator will be run by a single cylinder diesel engine, and the DC output of the Pi Filter can vary. I don't know what value of 120 Hz noise the GTI can tolerate, but, I suspicion that it could tolerate at least 1 to 2 volts Peak to Peak.
Can any of you offer assistance in this? Thank you very much.
XHoosier Located in Lakeland, Florida

 

[mramos1]

OK someone brought the thread back to life.. So we must ask if Nigel pulled his generator out and got it running yet..

If it was a new PIC chip/programmer/MPLABS release he would be all over that...