Can someone explain what 2 voltamps translates into as far as amps?

:Can someone explain what 2 voltamps translates into as far as amps?
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:Hi! Robert,
Volts X Amps = Watts If you have a circuit voltage of 120 volts and a 1 amp load = 120 watt
2voltamps = 2watts
to get amps---120watts divided by 120 volts=1 amp
If you need to get more technical ,google voltamps,and you will find an in depth explanation of why voltamps is the correct term only in a/c circuits and why. Bob Masse
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A 2-VA xfmr is pretty small. What's it used for?

But you have to know the rated voltage to compute the rated current.
Doug

:Can someone explain what 2 voltamps translates into as far as amps?

I bought them as surplus and thought I could use 2 of them (in and out) as transformers for a B suppply someday.

:A 2-VA xfmr is pretty small. What's it used for?
:
:But you have to know the rated voltage to compute the rated current.
:Doug
:
::Can someone explain what 2 voltamps translates into as far as amps?

:I bought them as surplus and thought I could use 2 of them (in and out) as transformers for a B suppply someday.
:
::A 2-VA xfmr is pretty small. What's it used for?
::
::But you have to know the rated voltage to compute the rated current.
::Doug
::
:::Can someone explain what 2 voltamps translates into as far as amps?

If you are lighting up lightbulbs or heating resistors, two VA is equal to two Watts. But, since you can connect them to things with capacitors and coils which screw up the the VA/Amp relationship all to ****. So to cover their butts, the manufacturers say: "This transformer will put out X Volts (probably on the case) but lets say 6. So at our six Volts output, P=EI, I=P/E, I=2/6, I=.333A
Lewis

P. S. Hallicrafters is shaping up nicely

Let me double check the transformer before this goes too far along,I've left out some important information. I believe the output is about 14 or 17 volts, rated at 2 voltamps, input at 120 volts.

::I bought them as surplus and thought I could use 2 of them (in and out) as transformers for a B suppply someday.
::
:::A 2-VA xfmr is pretty small. What's it used for?
:::
:::But you have to know the rated voltage to compute the rated current.
:::Doug
:::
::::Can someone explain what 2 voltamps translates into as far as amps?
:
:
:If you are lighting up lightbulbs or heating resistors, two VA is equal to two Watts. But, since you can connect them to things with capacitors and coils which screw up the the VA/Amp relationship all to ****. So to cover their butts, the manufacturers say: "This transformer will put out X Volts (probably on the case) but lets say 6. So at our six Volts output, P=EI, I=P/E, I=2/6, I=.333A
:Lewis
:
:P. S. Hallicrafters is shaping up nicely

:Let me double check the transformer before this goes too far along,I've left out some important information. I believe the output is about 14 or 17 volts, rated at 2 voltamps, input at 120 volts.
:
:::I bought them as surplus and thought I could use 2 of them (in and out) as transformers for a B suppply someday.
:::
::::A 2-VA xfmr is pretty small. What's it used for?
::::
::::But you have to know the rated voltage to compute the rated current.
::::Doug
::::
:::::Can someone explain what 2 voltamps translates into as far as amps?
::
::
::If you are lighting up lightbulbs or heating resistors, two VA is equal to two Watts. But, since you can connect them to things with capacitors and coils which screw up the the VA/Amp relationship all to ****. So to cover their butts, the manufacturers say: "This transformer will put out X Volts (probably on the case) but lets say 6. So at our six Volts output, P=EI, I=P/E, I=2/6, I=.333A
::Lewis
::
::P. S. Hallicrafters is shaping up nicely

I obtained a couple of filament transformers, 120/6 Volt, 20 Amps. I found a box that they fitted just fine, and made myself an isolaion transformer by wiring them back to back. Now six Volts and twenty Amperes equals 120 VA. This thing must weigh 15 or 20 pounds, and only puts out 120 Watts, which is fine for safely isolating radios from ground, and it has 3000 Volts of isolation.
Lewis
Lewis

The VA rating of the primary winding is essentially the same as the secondary. So, the rated secondary current rating is about 2VA/17V = 110mA. That is terribly puny, and probably not usable for any tube-type radio application that I can think of. Certainly not for two xfmrs back-to-back used as an isolation xfmr - nor even for a B+ supply. I wouldn't even ring your doorbell.

Assuming the turns ratio is 120:17, I don't think it could be used for a tube plate supply, even if the current rating were higher.

I realize you bought these xfmrs surplus, but I'm really wondering about the original application of a 2-VA xfmr. The dinky thermostat xfmr for my furnace is rated 40VA.

How sure are you of the 2-VA rating? I think such a transformer would almost fit in a large thimble.
Doug

::Let me double check the transformer before this goes too far along,I've left out some important information. I believe the output is about 14 or 17 volts, rated at 2 voltamps, input at 120 volts.
::

I'm thinking there must be a misunderstanding here. A 2-VA xfmr would barely handle the dial lamp of many old radios.

Can you post the exact nameplate verbage or whatever you are going by?
Doug

:I'm thinking there must be a misunderstanding here. A 2-VA xfmr would barely handle the dial lamp of many old radios.
:
:Can you post the exact nameplate verbage or whatever you are going by?
:Doug

I just remembered something. The Princess telephone had a #47 bulb to light up the dial. The Princess transformer was 1.73 VA @ six Volts. That might sive you some idea of what 2 VA is capable of.
Lewis

Here are the exact specifications:
120v 60hz / 17v 2.5va Smallwood BTX-1389 class 2

::I'm thinking there must be a misunderstanding here. A 2-VA xfmr would barely handle the dial lamp of many old radios.
::
::Can you post the exact nameplate verbage or whatever you are going by?
::Doug
:
:
:I just remembered something. The Princess telephone had a #47 bulb to light up the dial. The Princess transformer was 1.73 VA @ six Volts. That might sive you some idea of what 2 VA is capable of.
:Lewis

Hmmm. OK, just for grins, about how big (physically) is the xfmr? Can you estimate its weight?
Doug

:Here are the exact specifications:
:120v 60hz / 17v 2.5va Smallwood BTX-1389 class 2
:

The transformer is about 1.5" square and would weigh about the same as a roll of electrical tape. Thanks for everyone's assistance in this.
Robert

:Hmmm. OK, just for grins, about how big (physically) is the xfmr? Can you estimate its weight?
:Doug
:
::Here are the exact specifications:
::120v 60hz / 17v 2.5va Smallwood BTX-1389 class 2
::
:

:Here are the exact specifications:
:120v 60hz / 17v 2.5va Smallwood BTX-1389 class 2

P=ExI, so I=P/E, or I=2.5/17, or I=.147 A, or 147mA of current.

Lewis

::Here are the exact specifications:
::120v 60hz / 17v 2.5va Smallwood BTX-1389 class 2
:
:P=ExI, so I=P/E, or I=2.5/17, or I=.147 A, or 147mA of current.
:
:Lewis

P. S., Class 2 means you can use doorbell wire or something like that.
LL

I think also that Class II xfmrs are inherently protected against a short or overload due to the winding impedance. So, they don't have to be fused (e.g., doorbell xfmr).
Doug

:I think also that Class II xfmrs are inherently protected against a short or overload due to the winding impedance. So, they don't have to be fused (e.g., doorbell xfmr).
:Doug

Sir Edd:
I believe it was the very first Princesses that had the #47. It had a short life span, and later they did change it to an easier to replace bulb, but they used the same transformer. All telephone people Hated the Princess phone, be it installing the thing, working on it or whatever. Most customers hated it too, because when you dialed a rotary dial, the phone spun around on the table. Things got better with Touch Tone, but the princess was a pain to install, repair, or use.
Lewis

:I think also that Class II xfmrs are inherently protected against a short or overload due to the winding impedance. So, they don't have to be fused (e.g., doorbell xfmr).
:Doug

Right you are, Doug.
The transformer is so puny that it cannot put out enough current to get the external wiring hot. Stereo speakers, intercooms, telephones, security systems, etc are all class II. Your 120/240 A wiring is class I, and has a compeletely different set of rules about how it is run in the house.
Lewis

:I think also that Class II xfmrs are inherently protected against a short or overload due to the winding impedance. So, they don't have to be fused (e.g., doorbell xfmr).
:Doug

Right you are, Doug.
The transformer is so puny that it cannot put out enough current to get the external wiring hot. Stereo speakers, intercooms, telephones, security systems, etc are all class II. Your 120/240 A wiring is class I, and has a compeletely different set of rules about how it is run in the house.
Lewis

:I think also that Class II xfmrs are inherently protected against a short or overload due to the winding impedance. So, they don't have to be fused (e.g., doorbell xfmr).
:Doug

You are right, Doug. The class II wiring is for telephones, stereo speakers, intercoms, security systems, etc. The class I wiring is for the 120/240 house wiring and has a compeletly different set of regulations that have to be followed when wiring that.
Lewis

Lewis L.,

Technically shouldn't the transformers power factor be taken into consideration in figuring the transformer's power using its VA rating?

Radiodoc
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::Here are the exact specifications:
::120v 60hz / 17v 2.5va Smallwood BTX-1389 class 2
:
:P=ExI, so I=P/E, or I=2.5/17, or I=.147 A, or 147mA of current.
:
:Lewis

:Lewis L.,
:
:Technically shouldn't the transformers power factor be taken into consideration in figuring the transformer's power using its VA rating?
:
:Radiodoc
:*****************
:
Radiodoc:
Using a purely resistive load, the Wattage and the VA are the same. The manufacturer uses VA as he has no control over what kind of load you are going to connect it to. Into a resistive or inductive load, a Voltmeter and an Ammeter will read totally higher VA than a Wattmeter, do to the phase difference between the Voltage and the current.
Lewis
:::Here are the exact specifications:
:::120v 60hz / 17v 2.5va Smallwood BTX-1389 class 2
::
::P=ExI, so I=P/E, or I=2.5/17, or I=.147 A, or 147mA of current.
::
::Lewis

::Lewis L.,
::
::Technically shouldn't the transformers power factor be taken into consideration in figuring the transformer's power using its VA rating?
::
::Radiodoc
::*****************
::
:Radiodoc:
:Using a purely resistive load, the Wattage and the VA are the same. The manufacturer uses VA as he has no control over what kind of load you are going to connect it to. Into a resistive or inductive load, a Voltmeter and an Ammeter will read totally higher VA than a Wattmeter, do to the phase difference between the Voltage and the current.
:Lewis

Lewis Part II:
The transformer doesn't have a power factor, the PF comes from what it is connected to. Or, the power factor is W/VA, which is close to one for a light bulb (resistor), or close to zero for a pure capacitor or inductor (reactor). Now feeding a transformer into a PF of zero, you will get zero Watts, while a Voltmeter-Ammeter arrangement will read VAs, and plenty of them.
So, once again, since the maker of the transformer cannot control the power factor of what it is connecd to, rather than Watts, they rate the transformer in VA
instead of Watts. By the way, shen the advertise those capacitor thingies on TV that show the Amperage of a fridge going down when it is connected in circuit, if you had a Wattmeter connected in the circuit it would show very little, if any, change. You are making the power company happy bu raising the power factor (canceling out some of the inductive load with capacitors) but the kiloWATTmeter on the side of the house doesn't know about it, as the field of that thing (Volts) is at zero when the current (Amps) is at max. A Voltmeter (VA) and a Wattmeter (Watts) only read the same with light bulbs, electric blankets, toasters, ovens, etc,.
Sometime, you will see capacitors on top off a pole, with a timer down on the side of the pole. This means there is a factory or something with a lot of motors, etc. nearby and they correct the power factor while the factory is in operation (hence the timer).
Lewis

::::Here are the exact specifications:
::::120v 60hz / 17v 2.5va Smallwood BTX-1389 class 2
:::
:::P=ExI, so I=P/E, or I=2.5/17, or I=.147 A, or 147mA of current.
:::
:::Lewis

Transformers are rated in VA rather than power (W). The temperature rise (and the losses) of a xfmr are related to the load VA rather than the load W.

For example, assume that the load is purely inductive (or capacitive). The power delivered to the load is zero (because the load current and voltage are 90 deg out of phase). But the xfmr may get quite warm, even hot, because: A)the winding is carrying current, giving I^2R losses, and B) the core is continually being magnetized and remagnetized, causing core losses.

But, yes, if you are given load power (W) and, say, the voltage, then to compute xfmr current (A), you need to know the load's power factor.

Now, I forget, what was the question? ;>)
Doug

:::
:::Technically shouldn't the transformers power factor be taken into consideration in figuring the transformer's power using its VA rating?
:::
:::Radiodoc
:::*****************
:::

Just wanted to try to get some constructive dialogue going for a change. Thanks.

Radiodoc
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:Transformers are rated in VA rather than power (W). The temperature rise (and the losses) of a xfmr are related to the load VA rather than the load W.
:
:For example, assume that the load is purely inductive (or capacitive). The power delivered to the load is zero (because the load current and voltage are 90 deg out of phase). But the xfmr may get quite warm, even hot, because: A)the winding is carrying current, giving I^2R losses, and B) the core is continually being magnetized and remagnetized, causing core losses.
:
:But, yes, if you are given load power (W) and, say, the voltage, then to compute xfmr current (A), you need to know the load's power factor.
:
:Now, I forget, what was the question? ;>)
:Doug
:
:
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::::Technically shouldn't the transformers power factor be taken into consideration in figuring the transformer's power using its VA rating?
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::::Radiodoc
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