power factor

[Besoeker]

Okay I first try give a outline of principles involved.We have to agree first.

%voltage increase = KVAR of capacitor x% impedance of transformer
............................. KVA of Transformer

% impedance of transformer may be 2 to 9% and depending on the low lagging power factor of load, KVAR of capacitor may be equal to KVA of Transformer.So a voltage rise of 9% can exist.By selection of cable with suitable voltage drop/meter,the entire voltage increase of 9% may be dropped along the cable connecting the load so that rated voltage is available across the loads terminals.But if permissible voltage variation across loads terminal is 5%,it may be exceeded at very light load condition.

Bit of a muddle, old chap.

This:
" %voltage increase = KVAR of capacitor x% impedance of transformer
............................. KVA of Transformer"
might have been taken as a rule of thumb from anywhere. It takes no account of the transformer impedance components, supply impedance or other connected loads. I prefer to work from actual values.

% impedance of transformer may be 2 to 9% and depending on the low lagging power factor of load

Transformer impedance is what it is.It's usually stamped on the nameplate. It doesn't depend on loading.

So a voltage rise of 9% can exist. By selection of cable with suitable voltage drop/meter,the entire voltage increase of 9% may be dropped along the cable connecting the load 9% may be dropped along the cable connecting the load

Not in the real world.

 

[T.M.Haja Sahib]

Bit of a muddle, old chap.

This:
" %voltage increase = KVAR of capacitor x% impedance of transformer
............................. KVA of Transformer"
might have been taken as a rule of thumb from anywhere. It takes no account of the transformer impedance components, supply impedance or other connected loads. I prefer to work from actual values.

The above formula takes into account % impedance of transformer.It does not take into account supply impedance or other connected loads because the voltage rise in secondary circuit of transformer only is considered and capacitor is assumed to be connected across the secondary leads of the transformer respectively.This formula is not rule of thumb and it was taken from link at post#14.

Transformer impedance is what it is.It's usually stamped on the nameplate. It doesn't depend on loading.

I am afraid you misunderstood.% impedance of a transformer is a fixed quantity.Depending on the design,it may vary from to 2% to 9%. Please read my post again.

Not in the real world.

Only principles are examined now for applicability.

 

[Besoeker]

Removed

 

[Besoeker]

The above formula takes into account % impedance of transformer.It does not take into account supply impedance or other connected loads because the voltage rise in secondary circuit of transformer only is considered and capacitor is assumed to be connected across the secondary leads of the transformer respectively.This formula is not rule of thumb and it was taken from link at post#14.

And clearly called an estimate.

A definition for you:

A rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination.

Yeppers. Rule of thumb it is.

 

[srinivasan]

Good observation, the wording is too exact to be coincidental, I think you are right, or at least someone has plagiarized something somewhere in this.

While I agree with most of what is said in that course, I think the issue of voltage rise is at best overblown as to importance and in some aspects just incorrect. For example I'm sick and tired of hat "conductor size" argument. Conductor sizing is based on code rules, not power factor correction, it's a spurious argument.

i have that article when i read that article only doubt arise to me... power factor improvement is advantage one but that article describe voltage rise problem when higher power factor correction .... sorry if i did any mistake ... and thanks because i asked one doubt but you teach me lot ....