Author Topic: Industry uses "Jerry Riged". (Read 2180 times)

Jerry · « **on:** April 02, 2006, 09:42:21 PM »

As you stated the other day. You didn't want to open that can of worms again.

Sorry just couldn't help myself. I think with that long debate the general consensus was I was kinda out on a lime with my ideas.

I think it was also sugested that industrial electronics would only use either delta or star and I was the only one to use "Jerry Riged".

Last summer a good freind with a steel fabrication and machine shop gave me 2 pieces of equiptment. He needed the room and I like old electronic stuff.

1 piece was and old (60s maybe) Arco/miller welder. It sat around in my shop for a while then I needed some room. So I took it apart and scraped most of it. This thing was big. 500LBs maybe?

I kept a few parts, like the 2 GE panel meters. 1 reads 50 volts the other reads 800 amps. This thing is DC and operates from 3 phase AC. 3 phase AC in one big DC output.

I also kept the realy big 21" X 11" X 7" 35 LB selenium rectifyer.

This is were the "Jerry Riging" comes in. I never thought about it at the time but it just hit me last night. Each phase had its own very big variable transformer. Each transformer had 2 wires comming out these wires went to 2 studs on the big selenium 6 AC studs all together and just 2 DC studs.

The big selenium is basicly 3 sperate fullwave bridge rectifiers with all its DC outputs wired perelell (HMMM jerry riged).

I'm thinking OK the manufacture wanted this welder to work efficiently, without eccess heat and get all the power out for the copper they put in and they didn't use star or delta? And this unit is changing 3 phase AC to a common DC power (HHHMMM just like wind generators HHMM).

Heres a couple pix.

I'm sure they don't call it jerry/riged. And I know I'm not the first to use this wireing sceem.

The other piece of equiptment was a vary large battery charger. Its used for electric fork fift trucks and such. It is way newer and I didn't tear that one up its still all complete. Memory also served me on this one also. So you guessed, I got up all fired up this morning, went out to the shop and poped the cover off.

This unit is built by Charter Power Systems, Inc. Specs are 208v, 230v, 460v at 14a, 12a and 6 amps. output is 24 volts at 135 amps. I think this thing only weighs about 250 LBs. It measures 32" X 22" X 24".

Just like the welder its powered from 3 phase AC and has one DC output and in this case is a battery charger( HHMMM wind generator).

It also has 3 seperate transformers, one for each phase and the secondaries of each transformer go to there own and seperate fullwave bridge rectifier and the DC outputs of the rectifiers are the perelelled (HHHMMMM Jerry/riged).

OH well I don't mind not being the first at least I'm in very good company useing this wireing scheem.

This is just a couple examples I'm sure there are many more.

Here are some pictures and the schimatic.

Thanks for the chalange guys. When its sugested that you may be wrong it makes for very good insperation. The can of worms is still there I just havn't dumped them all out yet. LOL

Chalenges is a good thing, It just makes us try harder. I'm not done yet. I'll keep digging at it till I've exausted all my energy.

OK Bring it on. I can take it. LOL.

JK TAS Jerry

coldspot · « **Reply #1 on:** April 02, 2006, 05:01:58 PM »

Ahhh-

Good to be "Jerry" !

And the jerryrigging is just what it takes.

Thanks Jerry

nothing to lose · « **Reply #2 on:** April 02, 2006, 05:37:54 PM »

Interesting equipment there.

Well, If I recall correctly, about Half the USA military equipment in WWII was run on "JERRY RIGGED" also

Huh, well other kind of Jerry Rigged I geuss, but Jerry Rigged always seems to work well for about anything if done right.

willib · « **Reply #3 on:** April 02, 2006, 05:48:50 PM »

Hmmm interesting ..

but the output ( low side ) of the transformers are center tapped.

did you center tap your coils ?

i think not. sorry jerry the jury is still out..

nice try though..

oztules · « **Reply #4 on:** April 02, 2006, 06:54:10 PM »

I can't work out why you feel that this makes a difference. It just a cheaper more reliable way to achieve full wave rectification of each phase ...ie. jerryrig.

Jerry's circuit is essentially the same.

............oztules

Nando · « **Reply #5 on:** April 02, 2006, 07:09:58 PM »

This charger is set for full wave DELTA rectification.

It is standard way and also the transformers are FERRO-RESONANT transformers to keep the output regulated -- the whole affair NOT loaded is 85 to 90 % efficient -- because the Ferro-resonant that saturates the intermediate core shunt.

So it needs accurate AC frequency for proper operation, the primary independent and isolated from the resonant side and the rectifier.

You can separate them and have 3 chargers each capable of 135/3 = 45 amps

The plate photo with the specifications is un-readable.

It has 460 volts, so the primary is dual winding with low voltage tab.

You may remove the capacitor and even supply AC voltage to that winding -- but since I do not know the transformer characteristics I can not tell you what to do.

Nando

willib · « **Reply #6 on:** April 02, 2006, 08:09:11 PM »

did you ever have one of those days where nothing goes right?

i quess i was just being argumentative, which isnt really like me to be that way.

my apologies Jerry

oztules · « **Reply #7 on:** April 02, 2006, 09:32:09 PM »

Jerry, I think it is jerry rigged

I think the use of the ferro-resonant transformers, precludes the use of proper delta configuration. If the secondaries had AC currents able to circulate throughout the secondaries, then the circulating currents set up by the variable "Q" resonant circuits would generate more losses.

I think that this is three independantly rectified systems precisly because this (jerry rigged) system stops any AC circulating currents from further degrading the transformers efficiency.

I wouldn't consider driving the resonant windings (600v secondaries) direct if you intend to use it for Battery charging, as it is a tight magnetic coupling, and this is exactly what you don't want for battery charging. The resonant circuit between the primary and resonant secondary is what gives the flexable magnetic coulpling in normal operation.

In practice, changing the capacitor to different values will give different charging characteristics....I think it detunes the resonant circuit. Can be useful.

Some may call it delta, but by your defintiions, I will call it Jerry rigged.

..............oztules

Jerry · « **Reply #8 on:** April 02, 2006, 09:35:44 PM »

HI Guys.

I almost made coment on the 2 doides with center tap transfomer secondary being fullwave in the post.

I knew some one would call me on this one. It is as full wave as 4 doides in the bridge configuration.

It could as well been the convetional 4 doide full wave bridge. If the transformer was left the same but the 2 doides were replaced with the 4 diode fullwave bride and center tap was not used the voltage would be twice as high. If the center tap and one transformer secondary lead was used the volage would be the same and the amperage would be half.

However in either case this power supply would still be wire jerry/riged and not delta or star. However it is equal to delta without slight diferances between phase causeing that unessary current to flow.

HI Nando. I'm thinking of useing 2 of the supplies in the charger to keep my 48 volt battery bank topped off during are frequent and some times long no wind spells here.

The ferro resonat transformer is used for regulation. However even if the transformers were of standard type this charger would still be jerry/riged.

About the center tap thing. Wind generator alt coils could be wound with center taps. Or a coil center tap in a coil can be created by winding coil wires 2 in hand.

Indeed this is what I did when I wound the 3 coils in the 6 slot 3 phase motor conversion test alt.

With center taped coils 2 doides could be used rather then a 4 doide fullwave bridge.

Its not common practice because its rather bulky and clumzy but the preformace results could be the same.

I'm thinking I'd best draw some schimatics again to help with diferances but strong simularities between these 2 methods.

Thanks for the feedback guys. Keep it up.

JK TAS Jerry

Jerry · « **Reply #9 on:** April 02, 2006, 09:55:55 PM »

Hi Oztules.

The Large welder used convention transformer wisdom. It was also jerry/riged.

I will seperate the 3 phase conection of the transformers in the charger. I have used 24 volt Ferro resonat wheel chair chargers on the same battery bank at the same time with good results. This will be no diferant.

It will be equal to haveing two 230 volt single phase ac X 24 volt DC battery chargers conected to the same battery bank. There are no issues in doing this

My battery bank is 48 volts. One charger will charge the top 24 volt, the other the bottom 24 volt groups. I do this at my store with my 120 volt battery bank and it works great.

The manufacture says this charger is regulated at 28.4 volts. Half of that is 14.2.

14.4 volts is typicaly what we see car alternaters set at. This means it can be left on indefinatly.

I know I've taken very long trips, many many HRs and the lead acid battery under the hood never complained about the 10 HRs straight of 14.4v.

JK TAS Jerry

oztules · « **Reply #10 on:** April 02, 2006, 10:21:39 PM »

All sounds good to me.

I have had several hundred 36v and 24v (from 15-50 amps)ferro resonant chargers in my time, and they work well,.... except for the occasional capacitor drying up....

Voltage regulation too??? spoilt rotten my good man

keep up the good work Jerry

.............oztules

Flux · « **Reply #11 on:** April 03, 2006, 01:17:20 AM »

As far as I can see the drawing shows a 6 phase half wave rectifier.

Flux

oztules · « **Reply #12 on:** April 03, 2006, 02:25:26 AM »

There are some truly wicked people wearing evil grins somewhere here abouts :-)

Nando · « **Reply #13 on:** April 03, 2006, 10:21:43 AM »

Jerry:

I do not know what you mean by : jerry/riged - Explain in detail !

Yes you could remove the center tap connection and use the winding with double voltage and a full wave rectifier at half the current.

BUT YOU DO NOT NEED TO DISCONNECT THE CT connection, just add 2 more diodes to each transformer ( negative rectification) and move the negative output going to the center tap to the negative side of the 2 added diodes negative rectification.

This way with a SPDT switch to select either the center tap of the Negative diodes you obtain double voltage settings -- this is the arrangement I did many decades ago for a special charger for very heavy battery systems with desulfators included as well.

If you have 3 phase and use 3 full wave rectifiers, Still you have a DELTA connection, so if you connect the windings in DELTA you may use just 6 diodes to do the job of 12 diodes if wired as above with full wave rectifiers -- with high current rectification a good $ savings.

Of course, connection as a STAR with 6 diode rectification for 1.73 higher voltage and 1.73 lower current.

One needs to be careful, if you are going to charge batteries, to limit the charge current to a safe level to protect the charger and the battery.

For full wave rectifiers, I have used SCR angle triggering one for each phase.

Or use a high power Mosfet /IGBT with the corresponding high current choke to PWM the current levels, as well as, the output voltage regulation.

Jerry · « **Reply #14 on:** April 03, 2006, 12:11:40 PM »

Hi Flux.

Thanks for that statement. I will try to find time to explain with some diagrams and text the nature of 2 doides working with a center tapped transformer as being fullwave as compaired to a 4 doide bridge working with a none center tapped transformer also being fullwave.

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