Author Topic: 4.5kva output  (Read 1038 times)

glort

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Re: 4.5kva output
« Reply #15 on: February 04, 2019, 02:54:53 PM »

Hardly forgot, it's what makes it Kva or KW in the first place.
  My bet it is .8 Pf  if it is KVA

listeroil

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Re: 4.5kva output
« Reply #16 on: February 04, 2019, 07:44:25 PM »
It says PF .1 so does that make KW and KVA the same?

Mick
« Last Edit: February 04, 2019, 08:09:24 PM by listeroil »

listeroil

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Re: 4.5kva output
« Reply #17 on: February 05, 2019, 11:56:26 PM »
Heres a picture

BruceM

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Re: 4.5kva output
« Reply #18 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. 

mike90045

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Re: 4.5kva output
« Reply #19 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.


glort

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Re: 4.5kva output
« Reply #20 on: February 06, 2019, 09:21:47 AM »

Only when using shitty switching power supplies


You REALLY don't like switching power supplies do you Bruce?  :laugh:

I have a whole largish box of the things from different equipment that's come and gone. They do come in useful for some projects.

.1 would be a pretty low power factor but that is exactly how I have seen it stamped on nameplates more than once.

BruceM

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Re: 4.5kva output
« Reply #21 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.

https://hackaday.com/2019/02/05/what-happened-to-the-100000-hour-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.


 










glort

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Re: 4.5kva output
« Reply #22 on: February 06, 2019, 09:20:24 PM »

An AM radio with loud static between stations is an effective ''poor man's near field sniffer'' for checking home power EMI.

You have mentioned this before and I have been keeping an eye out to get a little transistor radio for this purpose but the things have become rare as hens teeth now. I saw a new one at an electronics store recently but it was clearly marked Digital and the was writing on the box indicating the digital circuitry made it much clearer and eliminated static. Apart from that the price was $100 which I couldn't believe for a little mono radio. I wondered who would want one now and Imagines an old bloke listening o the races or something but couldn't imagine  them paying exactly $100 for a little pocket radio.

I always keep a look out at markets etc but the only ones I have seen in the very few  did not look like they were capable of making a sound, static or otherwise. Why people would even offer busted radios I don't know but considering the other complete rubbish on offer.... 

I remember buying my grandmother a little transistor radio for Christmas. I think it cost me about $2 which was then for me a months pocket money. She sure got her moneys worth out of it though. Every morning she would sit and have her breakfast and listen to the news and talk back.  That little radio literally outlasted her and was going for years.  I'd love to be able to go back in time to that shop I bought it from. Was a dept store that sold practical things and I spent a lot of time in there with my mother and grandmother then later on wandering around myself. going to their large cafeteria  was always a treat as was getting a drink from the swirly machine up the front of Pineapple crush.  It was next to the hot roast chickens they would pull off the rotisserie for you and they did beautiful baked potatoes  and Boiled veggies.  You could get a real meal take away and even my grandmother thought they were cheap and good food.

Think I'll always feel I was born a couple of generations too late.


dieselspanner

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Re: 4.5kva output
« Reply #23 on: February 06, 2019, 09:52:21 PM »
Tighten 'til it strips, weld nut to chassis, peen stud, adjust with angle grinder.

BruceM

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Re: 4.5kva output
« Reply #24 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.

« Last Edit: February 06, 2019, 10:08:07 PM by BruceM »

glort

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Re: 4.5kva output
« Reply #25 on: February 06, 2019, 10:19:38 PM »

Geez, that was a shock to the system and memories that will throw me off for the day.

I found grans old Radio.

https://www.ebay.com.au/itm/Retro-Working-Mint-Condition-National-Panasonic-Radio-Vintage-Rare-Red-Colour/113594176012?hash=item1a72bd920c:g:dhwAAOSwmTBbcspC:rk:117:pf:0

Hers was black, I remember her being very insistent on  that but same unit.
$230!!!  I paid $2 odd new at Coles!  They sold them for years.

Might have to really look and see if I still have it.  Pretty sure I gave it to an aunt as a memento though.

Haven't seen any new ones yet.