power factor issue

[zoo123]

power factor issue at my shed , seek advice?

dear friends, i have a commercial power line taken from Govt owned lines, as is usual.

with my new start up, i registered for a min. use of 4kw and connections provided in 2021. I changed the same to permanent conneciton in end of 2023.
Since, then i have been using one welding machine mobile carry type and one hand grinder for weld work related fabrications. The wattage of weld machines never exceeds 2 KW,
and the hand grinding machine 0.5KW.

RECENTLY I WAS levied a heavy penalty for a very low power factor of 0.2. But, when i see the digital meter it shows 0.07 or around that.

I also, use a Capacitor bank unknowing on the conneciton method. but they keep charging me once again.

Now, upon, raising the query, the capacitor bank trader says for 4 to 6kw , this is an issue for low power and it can never be solved.

The govt department adviced me not to keep the capacitor nearr the mains, but shift it to my welding machine and switch it off and swith on during the usage only.

i am perplexed and unhappy that my start up is being robbed for no reason of mine. can i know what i must do to increas the pf and avoid the fines. please advice me.

thank you all.

 

[electricuwe]

From your description of load there is no reason to use a capacitor bank.

Your (small) welder most probably uses power electronics may even provide power factor correction and the grinder has low power and might rune in worst case at a power factor of 0.6 or 0.7.

 

[zoo123]

From your description of load there is no reason to use a capacitor bank.

Your (small) welder most probably uses power electronics may even provide power factor correction and the grinder has low power and might rune in worst case at a power factor of 0.6 or 0.7.

thanks for your inputs. but at the end of the day, the Govt people keep penalising my small start up intentions and heavy penalty levied on me. The power factor of 0.1 , means i utilise a current on a average of 5 to 8 amps, but with the VAR, iT SEEMS they pump in 150 amps. so, how i effectivly change the poor PF of 0.07 or 0.1 to 0.8 ,

 

[crshears]

Hmm, have I not seen threads in these fora relating to commercially available small scale power factor correction units for use at Point Of Common Coupling [ POCC ] ? You might want to do a search . . .

 

[zoo123]

meanwhile not sure what u meant by POCC. aLSO, It would be good to know if the capacitor can be kept on always or how it has to be connected. can you throw some lights. thanks though

 

[waross]

First, you don't supply enough information for an accurate assessment.
There are so many ways that various power companies calculate power factor for the purpose of penalties that just giving us the utility PF is not very helpful.

But here is an example that mat apply in your case;
Load: 1 kW, 1 KVAR, in use 0.5 Hr. per day.
VARHr used = 500 VAR Hr per day.
PF 50% lagging.

Correction of 1 KVAR switched with the load = 100% PF.

Correction of 1 KVAR on the mains = 23 KVARHr per day
(23.5 KVARHr leadinf minus 0.5 KVARHr lagging = 23 KVAR leading) leading current with a power factor of 2.17%

Either correct your welder to 100% with caps switched with your welder or hire an expert familiar with local tariffs.

 

[crshears]

Hello zoo, waross is correct; I agree more with his second recommendation, viz., you should find a local expert in power factor penalties.

My reference was to a power factor correction unit that connects at the point of common coupling, meaning where your electrical services and your power company interface. Such units measure the power factor of your site on an ongoing basis, and use controlled capacitors and/or reactors to adjust your site power factor to very close to unity [ 1.0 ] in real time; that way your utility will never find you with a poor factor, whether it be lagging [inductive] or leading [capacitive], and can therefore never assess such a penalty against you.

This can be very expensive to implement, though, hence the strong recommendation to find a knowledgeable power factor penalty expert for your area to assist you so you will not spend money unnecessarily.

 

[electricuwe]

You have to be aware that poor power factor can be caused by inductive load (lagging) or by capacitive load (leading). Unless you know your power factor without any capacitors connected you can`t decide.

Maybe you just pay the penalty for the capacitorys causing leading power factor.