Lister Engine Forum
How to / DIY => Generators => Topic started by: dkwflight on August 20, 2006, 06:36:58 PM
-
Hi I 've been running my 20k head for the last 2 hours or so. I checked the volts and hz with a Kill-a-watt meter and I am getting 204 volts at 60.5hz 17 amps load.
I am under the impression there is resister that can be adjusted to vary the voltage in relation to the hz. I don't see it. where could it be? I checked the slip rings, they are clean.
Dennis
-
HEre it gets interesting.
at 57.5 amps the voltage is 107 or 214 59hz
at 0 amps, no load volts 88 or 176 60.5
Dennis
-
Can you post me a picture of all the terminals and wiring associated with the field. Maybe I can spot something...
Its hard to give good advice when your not familiar with machine in question but I might be able to see something obvious.
Doug
-
Hi It is a power solutions typical st head as far as I know. I suspect the chinese diode pack. I took it out and checked what I could without unsoldering any thing.
Ive just been on Utterpower looking at the manual on line. The gen head did not have any paperwork with it. It had some brushes and a holder.
Its been working OK untill today. When I got it I checked connections and all looked good. The output voltage was what was expected.
I cleaned the slip rings before I fired it the first time.
Ithasn't been overloaded, the 28/2 won't take it.
Dennis
-
Do you have a Multy meter?
If you don't spend a few bucks and read the booklet with it ( get one with a diode check setting ). You can check the bridge easy enough. Forward biased diodes will drop .5 to .7 of a volt and block the opposite direction. There's nothging else to check, if its showing a short ( less than .5 volt ) or looks like it conducts in both directions its scrap.
I'd like to be more help but until I get my hands on an ST I can't give good advice.
Doug
-
Hi George has a trouble shooting manual on utterpower.com for ST heads. I have it but I hav'nt had a chance to work through this process yet.
Thanks
Dennis
-
Hi
I finally got a chance to go to radio shack. I bought a Part 276-1185 bridge rectifier. I chose this one because it had standard spade terminals. At $3.29 I will keep a spare.
Peak reverse volt 50v
rectified current 25a
Forward volt drop 1.7v
reverse leakage at PRV 100ua
cost3.29 +tax
The unit is running now at 20Amp at 230
Dennis
The old rectifier is hard to check with the multi meter but I found two that read the same forward and reverse.
-
Hi I ran the new rectifier at 20 amps on the gen head for almost 2 hours. The temp on the rectifier was at 116f by infared thermometer. The green paint in the sun was 110.
I jumped the load on the gen head up to 50 amps and the tempt jumped up to 125f in seconds. I will have to build a heat sink to keep it cool.
Dennis
-
Dennis,
I mounted my rectifier on the inside of the generator end plate (like in George's CD) and used some heat conducting gel. I haven't shot it with my pyrometer but there should be plenty of air moving in there to keep it cool. Its also easy to get to.
Glad you got it fixed inexpensively.
Rick
-
Hi I ordered a fancy finned heatsink from mouser.com. They have a huge selection of bridge diodes and just about anythin else you could possibly want.
I'll post a pic when I get it mounted.
Thanks
Dennis
-
While on the issue of bridge rectifiers.....does anyone have a part no. for a replacement on a 5KW ST generator? Or know where I can get one?
Thanks!
Dave
-
Hi I would use the same rectifier from radio shack. I think it will do the job. I won't heat up as much
Dennis
-
Dennis
Thanks.....I need a spare one that takes up less room...
Dave
-
Check ebay etc. for the rectifiers...I got 4 good sized ones (technical term for "I don't remeber the size") for around $10 + shipping. I color coded the terminals and the wiring harness they plug into with nail polish so that a quick chageout can be made ...
Joe
-
Guys....I'm a machinist not a "sparkey" I have done lots of wireing 3phase and single......but never a bridge rectifier. I can take it apart and put it back togeather but rectifier values.... ???....I'm in part number land...I did do a e-bay search and found the "archer" one ....but what are the nessary values it has to have?...Radio Shack has em in stock...easy!
-
What you would be looking for is a full-wave bridge rectifier. There are a lot of different sizes...I don't remember where I got the size info...but If I had to guess it would be from George's CD...I do believe they are available from him also...good to have a spare...then you'll never need it. :)
Joe
-
Hi I took a pic of theheatsink and diode. here it is.
http://s29.photobucket.com/albums/c294/dkwflight/?action=view¤t=100_0164.jpg&refPage=&imgAnch=imgAnch1
As you can see I haven't mounted it yet.
:D I need to clean the sooty oil up too!
Dennis
-
Found the diodes I got on ebay in Dec 05...have had them tucked away since then and not had a chance to do anything with them yet...
The only number on it is KBPC3510...don't know if this is a good replacement for the Chinese arangement that is standard on an ST 5kw...when dealing with electrical componets I would do more research and find a more credible source as to size than some unknown stranger on the net (me).
Joe
-
Hi I don't think the values are too critical.
I ran the gen with the heatsink under a good load to day. no problems with ir. It ran cool, maybe 1 degree above ambient.
I had some problems with throwing the belt tho. I had alowed the gen to get oput of alignmenmt with the drive pulley. Use a long straight edge to chec. put it across the driven pulley edge and look at the belt spacing.
Dennis
-
Guys....I'm a machinist not a "sparkey" I have done lots of wireing 3phase and single......but never a bridge rectifier. I can take it apart and put it back togeather but rectifier values.... ???....I'm in part number land...I did do a e-bay search and found the "archer" one ....but what are the nessary values it has to have?...Radio Shack has em in stock...easy!
Peak reverse volt 50v
rectified current 25a
Forward volt drop 1.7v
reverse leakage at PRV 100ua
Of course a diode conducts electricity one way and (almost) not the other way.
Peak reverse volt = how much voltage you can apply in the reverse direction without it breaking down and conducting.
rectified current = current that it is designed to carry, over that and it probaly will overheat and burnout.
Forward volt drop = when conducting in the correct direction you will get this amount of volts drop due to resistance.
reverse leakage at PRV = that amount of current that will leak when you apply the reverse voltage. 100 microamps in this case.
You can get different ratings for all of these things. Mostly need to be sure that PRV and Rectified current are high enough for the application. In this case 50 volts is way more that the 24-48 you'll have, and 25 amps is more than you'll be running through it.
There are four connections on a full wave bridge. Two are the AC connections, doesn't make any difference which wire goes on which connection. The others, marked (+) and (-) are the DC ones and the appropriate polarity DC wires should be wired to them.
-
I'm not a sparky I'm an elelctrican, the term sparky tends to make me think your a welder or a very unlucky electrican ).
Just a point I'd like to make about the PIV rating of diodes and bridges try and go double or a little better than the actual voltage required. This is cheap insurance that a voltage spike caused by any one of a number of things doesn't blow a diode.
Doug
-
Hi Sorry about the sparky crack. My mistake, I was looking at a photo by somebody who was drawing a big spark with a piece of wire from two power pole transformers powered up backwards from a 240 volt power supply. powered this way the 240 is stepped up to several thousand volts and will throw very impressive sparks. I don't remember who was doing that demo but an accident could be deadly.
And you are right, by useing a diode that has a rating higher than the source power supply you have a cushion to avoid future breakdowns.
Thanks
Dennis
-
Yes I also saw that photo and it made the hair on the back of my neck stand up. I even offered to send him a pair of 15 kV hot gloves but after reading his reply I see he seems to know what he's doing.
Arcs care the hell out of me, I have a small flash burn on my arm and I'm not eager to repeat the experince. I've had some scares working in high voltage and invariably the reasons were improper use of tools, PPE and not following the procedure. Another point often not spoken about is how hi the available falut current has become on todays power system. We now talk about things like arc blast and thermal energy at so many inchesr when we decide what level of protection we need to do a job becausea bad arcing fault can give you 3rd degree burns and metal vapour burns lungs. Arc blast, ,the presure wave caused by all that energy in a confined space and how far it likely to toss you back. As recently as Friday night I was checking the SCRs in large drive, doing a hot test on a very large machine and few people in my dept want to do that anymore out of the real fear of arcs and just how much energy is available.
And from an engineering stand point situations where you have power electronics and inductive circuts like field coil you go for a minimum of 2.5:1 margin. Many go much higher but this is the min you would wnat in a situation where some sort of inductive kick back or transient ( don't ask what kind on a machine this small I'm just talking in general ) to ensure the semicon device will servive.
Doug
-
bitsnpieces1,
Peak reverse volt 50v
rectified current 25a
Forward volt drop 1.7v
reverse leakage at PRV 100ua
In my box of diodes I have one that matches that spec exactly...it is a Radio Shack
# 276-1185..the price on it is $2.99....I have no idea how old it is or what the current price is...but the ones I bought last year on ebay were cheaper and bigger...
maybe way too much over kill?..... arrrgh... more power....
Joe
-
25 amps is just a tad more than your going to need, Id like to see a PIV between 100 and 200 volts just to be safe, but the lower end of that range is probaly already overkill. I have no idea wht the field current for that should be but I can't see it being much above 5-10 amps
-
Hi Doug
I don't know what the amps are running through the diode, I'll check tomorrow.
I would like to clean up my power. The computer UPS would not kick in and let me run my computert today.
Dennis
-
Has anyone ever tried an APC Line-R for voltage regulation after the generator? They are made in 300, 600, and 1200 watt. I suspect they are full of copper... they boost low voltage and clip high voltage... "melt" for lightning protection.
Might be good for stuff like computers, UPS, etc... give the appliance cleaner juice, maybe partially or fully overcome fluctuations from the generator?
I bought 3 of them and use them, even with grid power. I don't notice any difference but them I have never tried them on generator power yet.
-
Hi I bought the APC Line-R power conditioner. hoping to be able to run my pc off generated power. No Luck at all!
It didn't make any difference to the UPC. It still acts like there is no power present.
Dennis
-
Hi oke i am a sparky :P
Check your label on the gen. the field voltage and current are the ones you need.
always use bigger bridge rectiferers or install two two lower the loses and heat in the units.
Keep in mind the most off the cin. and indi. types are not so good. replace a.s.a.p.
also lower heat on the diodes means more current and voltage to the field coil means more magnetic field means more power.
yes it is another inprovment on fuel here and cheap.
greetings from Greece ;D