3 phase transformer tap changes savings
3 phase transformer tap changes savings
(OP)
Somebody mentioned that by changing the taps on a three phase transformer, it is possible to have a consumption saving.I do not agree cause, if the voltage goes up, the current will go down equally and supply the same amount of power OR because the load stays the same the voltage goes up and the current goes up- thus power goes up - more consumption? should lower the voltage-lower current - lower power - lower consumption?
Is there an impedance savings or something I am missing?
Is there an impedance savings or something I am missing?






RE: 3 phase transformer tap changes savings
Regards
Marmite
RE: 3 phase transformer tap changes savings
However, energy usage may not change in the same proportion as power demand. An electric water heater operating at a lower voltage will draw less power, but it still takes the same energy to raise a volume of water to a particular temperature, so the heating element just stays on longer.
We work with utilities that routinely reduce voltage to their customers in order to reduce their peak demand charges for wholesale power.
"Theory is when you know all and nothing works. Practice is when all works and nobody knows why. In this case we have put together theory and practice: nothing works... and nobody knows why! (Albert Einstein)
RE: 3 phase transformer tap changes savings
Bill
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"Why not the best?"
Jimmy Carter
RE: 3 phase transformer tap changes savings
The short answer is, it depends on what type of load you are looking at. dpc got it spot on!
If you are talking about resistive loads and lighting, then there are possible savings. If you are talking about induction motors, there are none, in fact if you reduce the voltage for a given absorbed shaft power, then current has to increase to develop that same power and the winding IR losses increase accordingly, so the motor actually generates more heat than at a higher voltage.
Be careful in motor installations designed at say 415V and then later reduced to 400V. The losses in the cabling will also increase because the volt drop will increase and then you might be operating the plant outside of the Regulations it was designed to.
RE: 3 phase transformer tap changes savings
A constant power load will draw the same power regardless of voltage.
A constant current load will draw power proportional to voltage.
A constant impedance load will draw power proportional to the square of the voltage.
While real loads don't fall neatly into these categories, they are typically responsive to voltage.
On some systems when they are close to brownout conditions (heavy system loading), a standard procedure is to drop the distribution system voltages by a few percent in order to reduce loads.
RE: 3 phase transformer tap changes savings