Capacitor bank

[sahan026]

I need to implement capacitors to improve power factor im my factory. there are 50% of AC motors, and the rest are DC.

01. which is more effective in following 2?
# implementing capacitor bank for the whole system or
# implementing individual capacitors for AC motors only.

02. What i Thyristor Control?

03. Pro's and Con's in using Capacitor bank and Thyristor Control.

 

[LionelHutz]

It's impossible to recommend the way to do it considering the lack of information and the fact it would need to be studied in detail.

I will say that any power factor capacitor banks may need special attention due to the potential for harmonics from the thyristor controls. De-tuning reactors and higher voltage rated caps may be necessary.

 

[mayanees]

Your first choice, or the "low hanging fruit", will be larger AC across-the-line (atl) started motors with 0.8 power factor.
Beyond that, the addition of pf correction caps in any electrical system needs to pay attention to harmonics that could cause problems.
And I shouldn't even make the blanket statement that the 0.8 pf atl motors are a safe bet for improvement because if the environment is dirty enough with harmomnics, it could still be problematic.
It really comes down to a requirement to model the system to account for THD, and pf correct accordingly, perhaps with tuner caps if required. But they're so expensive that they compromise the payback period.
PF correction is no longer routine, as it was prior to the prevalence of harmonics.
John M