Lister Engine Forum

How to / DIY => Generators => Topic started by: vegoil on October 10, 2018, 10:59:42 PM

Title: 4.5kva output
Post by: vegoil on October 10, 2018, 10:59:42 PM
what is the safe kw out put for a 4.5kva 230volt bkb generator on a Lister CS8/1 could I pull 4.2kw without doing damage? the power is being used into storage heaters and a immersion water heater on motors are used.

what would you say the maximim amps for the 4.5kva alternator as not to overload it?
Title: Re: 4.5kva output
Post by: vegoil on October 10, 2018, 11:57:49 PM
all the power is to go into elements in storage heaters I have one at 3.4kw on its own and a (2.5kw + 1.7kw) together giving 4.2kw also (3kw immersion +0.850kw) heater together, I am planning to have 3 time clocks one for each 3.4kw ,4.2kw, 3.8kw

what would be the maximim amps so as not to over load it?
Title: Re: 4.5kva output
Post by: BruceM on October 11, 2018, 02:01:12 AM
For a resistive load, VA is  the same as watts, so 4500/230= 19.5 amps
Just make sure the generator rating is a full load, continuous service and not some BS rating.
Title: Re: 4.5kva output
Post by: vegoil on October 11, 2018, 04:49:16 PM
thanks for the advice, its an old 1969 Lister CS 8/1 SOM with the original generator I have had the winding's tested and they are all good
I have tried to attach a photo (no go)

Cheers John
Title: Re: 4.5kva output
Post by: ajaffa1 on October 12, 2018, 11:17:13 AM
+1 Glort, old generators are rated for continuous output unlike the cheap Chinese crap they sell now. If it says 4.5 KVA that`s what you can run off it all day. The higher the load the more fuel you will burn but diesel engines need to be run hard or you get problems with cylinder glazing and carbon build up. Always good to fit a volt meter into the circuit so you can see how it is coping with the load, If you turn on a heavy load the voltage should drop a bit until the engine governor compensates by delivering more fuel. the voltage should then climb back towards nominal. Heavy loads tend to heat up the wiring a bit so there is usually a small voltage drop over about the first ten minutes until things reach a happy equilibrium.

If you are going down the route of timer relays, please use these to trigger proper power relays to distribute the AC current. The cheap Chinese timer relays are supposed to be rated at 20 Amps, I have had two fail in the last 18 months. One of them caught fire and could have burned my house down. I would recommend motor starter relays.


Title: Re: 4.5kva output
Post by: vegoil on October 12, 2018, 03:45:31 PM
I was going to use multiple 30 amp (Chinese) relays. the largest switching load per heater would be 15 amp I thought that I would give it a 50% margin, what do you think?

I have a amp,volt,and Hz meter fitted


Title: Re: 4.5kva output
Post by: vegoil on October 12, 2018, 05:04:21 PM
this is the relay on ebay that I Got? 250VAC 30A High Current Contactor Relay Switch 12V DC Board Module Powered Shunt

Is this the same one that gave bother?

 I have a photo but cant seem to get it posted here or any other photos for that mater.

Title: Re: 4.5kva output
Post by: listeroil on February 02, 2019, 06:26:12 PM
The 8/1 engined Startomatics with the 4.5kw BKB generator are rated for continuous use at 4.5kw.  However they are rated to BS1958 which states that the generator can be run at 10% overload for a period 1 hour in a 12 hour period. This is also true of the engine. They both conform to BS1958 spec. I do have a Lister brochure which gives this information but at the present moment it is buried under a massive pile, when I find it I will post a picture.

Title: Re: 4.5kva output
Post by: BruceM on February 02, 2019, 07:22:17 PM
A true 4.5KW is generous for most homes.  That's like a 6-8KW modern screamer genset.
Lovely machine!
Title: Re: 4.5kva output
Post by: listeroil on February 03, 2019, 09:38:15 PM
Just to be pedantic, although it does make a difference in this case, Both 4,5 KVA and 4.5 KW have been quoted for the same machine here.

You make a good point so I checked up my Lister manual and brochure for this particular unit and in all the publications it states 4.5KW.  Then I went and checked the brass spec plate on the actual BKB generator and it says 4.5 KVA.  I have now checked a few more Lister manuals and some of them say:-
8/1----4.5 KW----4.5KVA----230V----50CYCLES.     
All very confusing Listers seem to reckon KW and KVA are the same when in fact they are not the same. However IMHO KWs is what Lister advertise in there brochures and manuals and they would not state 4.5KW if it couldn't do that.  So I reckon this generator could easily handle the OPs 4.2KW.

Title: Re: 4.5kva output
Post by: oldgoat on February 04, 2019, 10:31:52 AM
All you pedants have forgotten to include the powerfactor which is usually stamped on the name plate that decides whether it is 4.5Kw or 4.5Kva
Title: Re: 4.5kva output
Post by: listeroil on February 04, 2019, 07:44:25 PM
It says PF .1 so does that make KW and KVA the same?

Title: Re: 4.5kva output
Post by: listeroil on February 05, 2019, 11:56:26 PM
Heres a picture
Title: Re: 4.5kva output
Post by: BruceM on February 06, 2019, 02:26:57 AM
VA and watts the same at a PF of 1, which is what it's rated for, not 0.1. 

For linear loads like resistive heaters and such, Watts and VA are the same.  Only when using shitty switching power supplies and lots of crappy low PF light bulbs will you see a big difference, though induction motors aren't so hot sometimes either and could use some more capacitance in parallel to reduce the VA.  Simple enough, just monitor V and A and add caps to minimize the total V times A.  It's very worthwhile to reduce often run motor VA for inverters- they do draw real PV or battery power to generate every VA, real or reactive.  I've confirmed that with a design engineer at Magnum and also myself on my own inverter design.  For motor generators, bad PF loads only cost you 15% more in fuel, but mostly it just eats your total capacity and motor starting capacity. 
Title: Re: 4.5kva output
Post by: mike90045 on February 06, 2019, 07:01:52 AM
And remember, that big old robust gear was built when a half gallon was 64 oz, not 60 oz like nowdays.

Title: Re: 4.5kva output
Post by: BruceM on February 06, 2019, 04:17:02 PM
Shitty switching supplies are the cause of much home power EMI.  There is no regulation of appliance emissions, and often the home wiring is a strong broadband radio transmitter for something as idiotic as a washing machine that is "off", or a cheap china battery charger left plugged in.  Or a new fancy digitalized heat pump system, etc., etc.  I think it's a foolish way to spend down your health.  It was idiotic to wrap ourselves in the unshielded power cables of our homes, but that is what we've done.

FYI-  Hackaday did a tear down on three LED bulbs.

The GE Basic and Classic bulbs have no switching supply, just bridge rectify the mains to an electrolytic capacitor, with a linear current regulator to the leds in series.  The results of this design-  fairly low EMI, just the emissions of the unsnubbed bridge diodes at 50ma of current.  It could be a Lister flicker problem if your voltage dips too much on the compression stroke, but it's likely OK for SOM's or those with AVRs.

The Cree bulb they tore down has a crappy little switching power supply, so lots of EMI but likely no Lister Flicker. 

An AM radio with loud static between stations is an effective ''poor man's near field sniffer'' for checking home power EMI.  The AM band is in the range of typical switching EMI harmonics.  If your home wiring is affecting much of the AM band, over 2 feet from the wires, you've got a serious problem that should be addressed.  Common mode chokes or other suitable commercial passive filters are one cheap and simple fix, that go between the offending equipment and the outlet. Those without a digital meter can quickly isolate problems by listening to the AM radio at the main power panel as you switch breakers off.  With a digital or smart meter, you can't do that as easily since the meter itself often has a laughably bad switching supply without any filtration at all; the power company doesn't have to meet any emissions specs, so dollar was saved.

Most computer switching supplies will at least meet conducted emissions standards, though that isn't saying much.  Appliances aren't regulated for conducted emissions, so anything goes.


Title: Re: 4.5kva output
Post by: dieselspanner on February 06, 2019, 09:52:21 PM
Hi Glort

Try this

there's a shed load in the UK
Title: Re: 4.5kva output
Post by: BruceM on February 06, 2019, 10:06:16 PM
I saw the Radio Shack 12-467 on the AU ebay, that's my favorite.
Sony makes a new cheap portable that's also pretty good as an EMI near field sniffer.  I can't find mine or I'd give you a model no.

There's still plenty of new cheap, non-digital AM/FM radios being made.  If you can hear loud static between stations, it should work fine.

Title: Re: 4.5kva output
Post by: listeroil on April 11, 2020, 01:37:41 PM
I said I had this brochure a year ago.  I have scanned it and cleaned it up a bit.  It shows how the engines were built to BS 649/1958 and alternators to BS 2613/1957 Both of them capable of being run continuously and 10% overloaded for up to an hour in 12 hours. So theoretically the Lister 4.5Kw alternator is capable of producing 4.94 Kw absolute max for an hour.