### Author Topic: transformer  (Read 11443 times)

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#### christos

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##### transformer
« on: January 11, 2014, 06:04:03 pm »
i have a transformer that get output 52 volts
its 10x10cm  very heavy
how do i know how many amps it can get at the output?
its    26-0-26

if you need pic i can show you

#### Rudane

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##### Re: transformer
« Reply #1 on: January 11, 2014, 06:22:05 pm »
Do you have any identifying numbers from the device? I'm not sure you can determine the maximum current out without knowing more information about the transformer.
Voltage appears across and current flows through.

#### christos

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##### Re: transformer
« Reply #2 on: January 11, 2014, 06:40:31 pm »
Do you have any identifying numbers from the device? I'm not sure you can determine the maximum current out without knowing more information about the transformer.
nothing..it got 2 secondaries 26v each

#### Simon123

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##### Re: transformer
« Reply #3 on: January 11, 2014, 06:42:47 pm »
Do you know, what it was connected to before?

#### IonizedGears

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##### Re: transformer
« Reply #4 on: January 11, 2014, 06:45:37 pm »
Do you have any identifying numbers from the device? I'm not sure you can determine the maximum current out without knowing more information about the transformer.
nothing..it got 2 secondaries 26v each

Assuming that your input is 120v, the ratio is 52/120(.4333) for the two combined secondaries  for V, or 120/52(2.3) for I. We could calculate this if you had the impedance of the main coil or the current through the main coil.
I am an EE student with interests in Embedded, RF, Control Systems, and Nanotech.

#### christos

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##### Re: transformer
« Reply #5 on: January 11, 2014, 06:46:40 pm »
Do you know, what it was connected to before?
a 40watt mic amplifier ..it used one more transformer at the output for the speakers

#### christos

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##### Re: transformer
« Reply #6 on: January 11, 2014, 06:48:55 pm »
Do you have any identifying numbers from the device? I'm not sure you can determine the maximum current out without knowing more information about the transformer.
nothing..it got 2 secondaries 26v each

Assuming that your input is 120v, the ratio is 52/120(.4333) for the two combined secondaries  for V, or 120/52(2.3) for I. We could calculate this if you had the impedance of the main coil or the current through the main coil.
input is 230v

#### IanB

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##### Re: transformer
« Reply #7 on: January 11, 2014, 06:51:03 pm »
i have a transformer that get output 52 volts
its 10x10cm  very heavy
how do i know how many amps it can get at the output?
its    26-0-26

if you need pic i can show you

The rating of a transformer is measured in VA (more or less the power handling).

Two ways to estimate the VA of a mains transformer are from the overall weight, or the dimensions of the core (height x width x thickness).

Given either or both of those, there are rules of thumb that will give you a ball park estimate.
I'm not an EE--what am I doing here?

#### christos

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##### Re: transformer
« Reply #8 on: January 11, 2014, 06:52:35 pm »
if i conect a  10ohm 10w res and measure the current..at the same time measure the tempp from the xformer ,,should it work?

#### IonizedGears

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##### Re: transformer
« Reply #9 on: January 11, 2014, 06:54:12 pm »
Well then, 52/230(.23)  for V, 230/52(4.2) for I. If you have the input impedance, then we could give you an exact answer. One way to do it is keep loading the secondaries until the voltage starts to drop and you could use E/R to find the max amperage for the secondaries this way.
I am an EE student with interests in Embedded, RF, Control Systems, and Nanotech.

#### IanB

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##### Re: transformer
« Reply #10 on: January 11, 2014, 06:55:28 pm »
if i conect a  10ohm 10w res and measure the current..at the same time measure the tempp from the xformer ,,should it work?

Item: the transformer provides 50 V
Item: the current through a 10 ohm resistor will therefore be 5 A
Item: the power dissipated in the resistor will therefore be 250 W

Conclusion: smoke will occur, if not flames
I'm not an EE--what am I doing here?

#### IanB

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##### Re: transformer
« Reply #11 on: January 11, 2014, 06:57:35 pm »
if i conect a  10ohm 10w res and measure the current..at the same time measure the tempp from the xformer ,,should it work?

As noted above the 10 ohm resistor is not a suitable load. But in general, increasing the load on a transformer until it starts to get warm is a good way to find the upper limit on the power handling.
I'm not an EE--what am I doing here?

#### christos

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##### Re: transformer
« Reply #12 on: January 11, 2014, 07:00:02 pm »
i have a transformer that get output 52 volts
its 10x10cm  very heavy
how do i know how many amps it can get at the output?
its    26-0-26

if you need pic i can show you

The rating of a transformer is measured in VA (more or less the power handling).

Two ways to estimate the VA of a mains transformer are from the overall weight, or the dimensions of the core (height x width x thickness).

Given either or both of those, there are rules of thumb that will give you a ball park estimate.
the core is 4x4x4

#### rdl

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##### Re: transformer
« Reply #13 on: January 11, 2014, 07:00:19 pm »
Quote
Do you know, what it was connected to before?
a 40watt mic amplifier

This might be a clue... or am I wrong?

#### christos

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##### Re: transformer
« Reply #14 on: January 11, 2014, 07:03:28 pm »
if i conect a  10ohm 10w res and measure the current..at the same time measure the tempp from the xformer ,,should it work?

As noted above the 10 ohm resistor is not a suitable load. But in general, increasing the load on a transformer until it starts to get warm is a good way to find the upper limit on the power handling.
so it may work?

#### kg4arn

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##### Re: transformer
« Reply #15 on: January 11, 2014, 07:04:28 pm »
If this helps get you in the ball park

I have 2 transformers here that I have weighed:
Hammond mfg rated at 30VA weight = 0.522kg --> 58VA/kg
Signal mfg rated at 100 VA weight = 1.22kg --> 82VA/kg

#### christos

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##### Re: transformer
« Reply #16 on: January 11, 2014, 07:07:01 pm »
ill post some pics

#### christos

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##### Re: transformer
« Reply #17 on: January 11, 2014, 07:32:02 pm »
well the core is 7 height 5 width 7 length
its 2.5 kg te metal is 9 height 11 width and 3 leght

#### IanB

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##### Re: transformer
« Reply #18 on: January 11, 2014, 07:37:19 pm »
the core is 4x4x4

well the core is 7 height 5 width 7 length
its 2.5 kg te metal is 9 height 11 width and 3 leght

In what units? mm? cm? inches?

When you give measurements you must always give the units of measure.
I'm not an EE--what am I doing here?

#### christos

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##### Re: transformer
« Reply #19 on: January 11, 2014, 07:43:19 pm »
the core is 4x4x4

well the core is 7 height 5 width 7 length
its 2.5 kg te metal is 9 height 11 width and 3 leght

In what units? mm? cm? inches?

When you give measurements you must always give the units of measure.
oups..read the new measurements if you didnt and its in cm

#### IanB

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##### Re: transformer
« Reply #20 on: January 11, 2014, 07:55:02 pm »
I cannot make sense of your measurements. The core is the metal part with the laminations that has the coils wound around the middle of it. The height and width will usually be as big as the transformer. The thickness will usually be less than the height and width.
I'm not an EE--what am I doing here?

#### christos

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##### Re: transformer
« Reply #21 on: January 11, 2014, 07:57:19 pm »
I cannot make sense of your measurements. The core is the metal part with the laminations that has the coils wound around the middle of it. The height and width will usually be as big as the transformer. The thickness will usually be less than the height and width.
oups at the core i mean the windings..ill post a pic

#### tasos987

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##### Re: transformer
« Reply #22 on: January 11, 2014, 07:57:25 pm »
IMHO reply #9 helps always to stay on the safe side....
Other bulk solutions i think include a minimal risk of smoke poduction
"All I know is that I know nothing" Socrates 470-399 B.C.

#### christos

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##### Re: transformer
« Reply #23 on: January 11, 2014, 08:01:06 pm »
I cannot make sense of your measurements. The core is the metal part with the laminations that has the coils wound around the middle of it. The height and width will usually be as big as the transformer. The thickness will usually be less than the height and width.
oups at the core i mean the windings..ill post a pic
http://postimg.org/image/cfu7djqjf/

#### christos

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##### Re: transformer
« Reply #24 on: January 11, 2014, 08:01:53 pm »
IMHO reply #9 helps always to stay on the safe side....
Other bulk solutions i think include a minimal risk of smoke poduction