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Old 12th September 2006, 05:06 AM   #1
kmtang is offline kmtang  Canada
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Default How to test transformer's current rating?

Hi,

I purchase 2 filament transformer with 6V and 5V secondary. Unfortunately there's no indication for the current ratings.

Wondering how could I find it out.


Thanks in advance.

Johnny
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Old 12th September 2006, 05:26 AM   #2
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J,
Let's think about this for a moment.

If we were to hook up said transformer to it's input. Let's say 120 VAC and If im not in error Canada is a 60 hz country your meter is going to see some kind of output near six volts.

We start to load the unit, watch on external meters your output current and voltage. I would use light bulbs or sand box resistors to slowly build up a load.

If memmory is any good at all, your going to reach a point where the voltage will fall off rapidly.
Back off the load a bit (let's say to 80%) and that is a good rule of thumb number. Let it run for an hour or two and see if it get's too hot.

This is due to the internal magnetics in the transformer overloading byond the cores ability to operate.

That's the easy answer, Im sure there are some brighter guys here who can give you a more exact answer. These guys here are very good.

At these very low voltages expect to get some good current out of fairly small transformers.

Keep an ear out for 'buzz' and watch how warm it gets. That will also put you into the 'overload' range.

Much luck on your project.
Jack Crow in Kuwait
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Old 12th September 2006, 05:30 AM   #3
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Quote:
Originally posted by Jack Crow
J[snip]These guys here are very good.[snip]Jack Crow in Kuwait

You'r pretty smart yourself, Jack!
Take care over there.

Jan Didden
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Old 12th September 2006, 05:52 AM   #4
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Janne,

Greetings to you.

Never made it to your country during R and R. Ireland, England, Amsterdam, and a little bit of Paris.

Gotta say, I like Europe. It's a very cool place. Lots of good food, fun people, and neat technology.

Civilized is good. Much better than Baghdad.

As for the question, I get stuff like this all the time here.

A trooper will come in and ask 'will this work'.

You would be amazed at the 'little stuff' that ties up units.

A refrigeration unit on a conex container failed. The troopers tried to sub in some other transformer. Still diden't work. In the middle of this effort they asked if the little parts on a circuit board were important, seems they knocked a few of them off and can't find them.

Things like that will make you pull your hair out.

That is why they hire guys like me. Your average tech sargent has a whole lot to do becides fix stuff. So when they get stuck they come to us for answers. When we get stuck, you know it's a heck of a problem.

Our current misery is civilian spec power generators.

Get a load of this.

We had one that never worked just right. One day it sputtered and quit.

The mechancs found a wire error in the magnetic pick up that ran the computer that sets the govorner. So they fix the error and the thing starts then runs away and shuts down on safety.

I spend some time on it, and discover the output to the selonid that drives the throttle is just fine. The guys had already ordered another computer controler. The beef here is, our mechanics never thought to use a portable scope to see what the waves were. That will change if I have any say in the matter.

The upshot of the whole deal was the magnetic sensor. It was making just too much signal, the A to D in the computer could not take the over load, and was reading the signal and it's digital distortion, causing the over rev trip.

The fix was to reposition the sensor. This is a huge 800kw D generator. Not subtle and very sensative.

It's amazing how the little things can bite you in the tail.

Hope all is well where your at.

One of the nice things here in Kuwait, I don't have to duck mortars.

Later dude
Jack Crow in Kuwait
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Old 12th September 2006, 05:57 AM   #5
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Hey, I'm in paradise. We do log support and contracting for the guys on operations where you'r at. We keep stuffing the supply lines, those guys keep losing the stuff at the other end. Need to slap RFID tags on those containers to keep track of them.

Have a great day,

Jan Didden
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Old 12th September 2006, 06:06 AM   #6
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J,
You can't imagine how big a business war is.

As for RF ID the Army has a tag system and sat coverage.

Some of our stuff you never want loose on the world market.

The convoys that move into and from Iraq are impressive. It's a huge logistics operation.

It's real impressive when an Armored unit is going places. Tanks, APC's and other tracked heavies.

As for the 'shrinkage' issue with your stuff, better act now than later to seal up your containers and keep track of them.

Theiving is a huge business up north.

Later dude
Jack Crow in Kuwait
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try ka2zev@yahoo.com
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Old 12th September 2006, 06:44 AM   #7
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Yeah. Anyway, let's not get into this on an open forum. Let's stick to audio!

Jan Didden
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