automatic power correction panel

[lewlec]

hi all

just wondering if any of you know anything about auto power correction? the reason i am asking is i have several 100amp single phase installations that are running at full capacity, so i was wondering if power correction would reduce the full load current? therefore reducing running costs? probably 80 - 90 amps of that are motors and maybe 5 - 10 amps are fluorescent lighting which do have pf capacitors fitted as standard. if any one has any info it will be greatly appreciated as i have no real experience in this field.

regards
gary

 

[IQ Electrical]

How are these supplies metered?
Most 100A supplies are on KW/h meters so you wouldn't make any savings.

 

[lewlec]

HI IQ

Ye they are meterd on kw/h meters, would it reduce the running current of the installation? as these are to their limits.

regards
gary

 

[IQ Electrical]

The current, voltage and power factor at the motor terminals do not change. The current and power factor between the capacitors and the supply are affected by the addition of the capacitors. The power drawn by the motor does not change. In effect, the capacitors are supplying some of the magnetising current of the motor, instead of it coming from the supply.

 

[Knobhead]

If we base the loading as purely inductive 100A @415V = 60KW @ .8PF
Adding 30KVAr of capacitors will lower the current to 87A @415V = 60KW @.95PF. It still equals 60KW that you will have to pay for.
You need to determine the loading of the motors on you system. The PF correction can not be switched in en-mass but needs to come in in stages. Otherwise you will have over correction
To be honest you should look at having your supply up rated and forget PF correction. There’s no financial gain from it with KWHr meters. If you were on KVA meters there would be.
If your thinking of lowering the line current by PF correction so you can add more load then I think your heading down a dangerous road.

 

[snaban]

What are the ratings of capacitors needed to a)correct pf b)reduce starting current of 1ph/3ph induction motors of different hp/rpm.Can someone give a link?.Thanks

 

[lewlec]

thanks for your replies

i thought it wouldnt be that simple, you are right upgrading supply would be the best solution, but the cost can be huge. so i was iust wondering could power correction be used.

many thanks
gary