Boosting power via transformers

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Toros

Senior Member
Location
Tujunga, CA
Hi, my friend, an electricion also said to his client who was worried about the existing service: 200A power (@ 124-240v-3-ph., 4w) available in his commercial bldg; that it might not good enough. " We can boost the available 200A power to more through transformers"
 

Toros

Senior Member
Location
Tujunga, CA
boosting power

boosting power

power no, current yes.
existing service is: 400A, @ 120/240v, 1-phase, 4-w Can he convert or make it to 500A @ 120/240V, 1-phase, 4-w through boosting xfrmers like he (my friend) proposed to his client???????????????????????
 

broadgage

Senior Member
Location
London, England
In general, no.

To be pedantic, the CURRENT could be increased but not the available power.

Or the service might be at MV with a customer owned transformer bank (and the so called "service" being in fact a feeder) in that case changing out the transformers could give more power, subject to the POCO having enough capacity at MV.
 

kwired

Electron manager
Location
NE Nebraska
Power is volts times amps (lets disregard power factor for now).

Power is going to remain constant as far as what the POCO can deliver without making changes to their equipment.

You can change voltage by installing a transformer but if power is to remain the same then the current is going to change in the opposite direction.

200 amps @ 240 volts gives you 48000 VA(lets assume single phase for simplicity) same power as 100 amps @ 480 volts, still 48000 VA - see how doubling voltage halved the current - yet total power remains the same.
 

dereckbc

Moderator
Staff member
Location
Plano, TX
Don't let that electrician do work for you.

Transformer are passive devices and incapable of boosting power. No device is capable of boosting power as that violates all Laws of Physics. No matter what device it is will loose power, even a transformer because no device is 100% efficient, and to boost power would mean it is more than 100% efficient thus above unity gain. Another word or Red Flag is Perpetual Motion Machine. Ever here some clown ask if he takes a battery and uses it to turn a motor which turns an alternator which keeps the battery charged and run your house lights? A real popular one today is water for gas con.

What a transformer does do is convert one voltage to another voltage, or simple isolation. When used to change one voltage to another, voltage and current are inversely proportional to each other, minus transformer Q losses (power). For example if you have a 2:1 ratio transformer with a input of 240 volts @ 10 amps, on the output you have 120 volts @ 20 amps. Note power is equal on both sides of 2400 watts. In real life practice the output power will be just slightly less than input from power losses (Q) in the transformer.

Another example but exact same physics apply is the Step-Up transformer say 1:2 with 120 volts @ 20 amps input, and 240 volts @ 10 amps output. The exact same 2400 watts on input and output. Again in real practices will be some slight power loss from Q.

Q is a number less than 1 or unity gain. No transformer will have a Q rating or 1 or more. It is impossible. Well it is possible using a special transformer that has a secondary power source like from an inverter used in a UPS, but that is just power being supplied from batteries in a buck/boost configuration. .
 

kwired

Electron manager
Location
NE Nebraska
Now if you insert another "source" you can change power, that source could be inserted via a transformer.

With AC power you also add to that the task of keeping both sources in phase with one another or you may not increase output power and could even decrease it, though technically that power doesn't disappear it is lost as heat - and probably damage to some components that couldn't take that heat.
 

Besoeker

Senior Member
Location
UK
In general, no.

To be pedantic, the CURRENT could be increased but not the available power.
The question to which I was responding:
existing service is: 400A, @ 120/240v, 1-phase, 4-w Can he convert or make it to 500A @ 120/240V, 1-phase, 4-w through boosting xfrmers
There is nothing to be pedantic about.
The answer is an unequivocal no.
 

Toros

Senior Member
Location
Tujunga, CA
In general, no.

To be pedantic, the CURRENT could be increased but not the available power.

Or the service might be at MV with a customer owned transformer bank (and the so called "service" being in fact a feeder) in that case changing out the transformers could give more power, subject to the POCO having enough capacity at MV.
Would you explain me diffrent way and more that I could understand. Thank you
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Would you explain me diffrent way and more that I could understand. Thank you
Go back to the basic principle that you cannot get more power out of a transformer secondary than you put into the primary.
That means that to increase the current you have to drop the voltage or vice versa.

If you have a 200A service at 480V, you can get more power out by having POCO change it to a 300A 480V service by changing THEIR service transformer and increasing the wire sizes.
 

drktmplr12

Senior Member
Location
South Florida
Occupation
Electrical Engineer
The service transformer would need to replaced or a second transformer connected in parallel to the main panel. The problem with this is if one of those transformers is taken out of service, the other will be expected to provide power for more that is it rated for. I am unaware if connecting two separately derived systems to a single bus is against NEC, but it is not a recommended practice.

If the customer wants more power, he needs to replace the service transformer, its primary conductors, secondary conductors, panelboard bus, and any associated OCPDs. Simply inserting a transformer will not increase power, as others have stated.
 

jtinge

Senior Member
Location
Hampton, VA
Would you explain me diffrent way and more that I could understand. Thank you
A mechanical equivalent to a transformer is a gear set. You can input a given power at a specific torque and speed and output the same power (minus losses) at a different torque and speed proportional to the gear ratio. Like a gear set, a transformer cannot increase power. Think of torque and speed in a gear set as analogous to current and voltage in a transformer. Power stays the same for both.


Sent from my iPhone using Tapatalk
 

kwired

Electron manager
Location
NE Nebraska
Would you explain me diffrent way and more that I could understand. Thank you
Go back to basic electricity 101.

Power is the product of voltage and amps. (VA) if power factor is 100% then VA = Watts

That is what power is for electrical applications, power is also equal to amount of work being done, and this view of power is seen on the prime mover that is driving the generator. You can not get more power from the prime mover then it is able to deliver, you can change output voltage to any level you want, but the current is also going to change proportionally at any power level.

If you have 200 amps @ 240 volts(single phase) you have 48,000 VA of power.

If you transform to 480 volts at the same level of power you will only have 100 amps of current.

If you transform to 120 volts at the same level of power you will have 400 amps of current.

Power in all three examples above is still the same, voltage and current is what has changed.

A generator (or other source) doesn't generate volts, it doesn't generate amps, it generates power which is the sum of the volts and amps. All you have to do to change volts is change the number of turns in the windings, and the amps will change accordingly. The size of conductor used for the windings and amount of insulation necessary will depend on how much voltage/amps the unit is designed for. But for the generator to be able to deliver more power at any voltage you must also have a prime mover capable of delivering that power. Carry this to the distribution equipment in question here and you still have a lot of the same things. The conductors can carry higher power if the voltage is increased, but the source transformer is still limited to same maximum output power no matter what you do for conversions on its output side. If you changed the source transformer to a bigger one then you have a stronger link in the chain and can get more power, but there eventually becomes a point where you can only go so much larger and then the supply side of that transformer will reach it's limitations
 

Jraef

Moderator
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
It's possible, in my opinion, that the FIRST statement may have been misinterpreted by the OP, who is obviously NOT an electrician, then HE made a leap to his second statement based on that. So yes, the second statement is absolutely untrue. But another interpretation of the first statement may be as follows:

Electrician: You are limited to 400A at 120/240V
User: Can I get 500A somehow?
Electrician: Not without changing the transformer.

What he may have meant was that the LIMITING factor in the size of the service drop is the transformer feeding it. You cannot increase the service capacity without increasing the capacity of the transformer.
 

kwired

Electron manager
Location
NE Nebraska
What he may have meant was that the LIMITING factor in the size of the service drop is the transformer feeding it. You cannot increase the service capacity without increasing the capacity of the transformer.
It is possible there is some misunderstanding here, but use of proper terminology can help straighten some things out as well. You do not boost power with a transformer, you only change characteristics of that power (primarily volts and amps and if you change one you will effect the other) within the power rating of the transformer, as well as the supply to the transformer.

Hi, my friend, an electricion also said to his client who was worried about the existing service: 200A power (@ 124-240v-3-ph., 4w) available in his commercial bldg; that it might not good enough. " We can boost the available 200A power to more through transformers"
 

kingpb

Senior Member
It is possible there is some misunderstanding here, but use of proper terminology can help straighten some things out as well...
Touche, and it's why I stress that stating voltage as 480Y/277V, 208Y/120V, 120/240V, 240/120V and 120/208V is so important. Stated correctly removes all doubt and needless interpretation.:D
 
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