Power Factor Correction - Capacitor Sizing wrt Motor Speed

[QwertyXP]

Please have a look at the following links:

http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/sa02607001e.pdf
(Table 3)

http://www.electrical-installation.org/enwiki/Power_factor_correction_of_induction_motors
FigL24)

- For power factor correction, why would the capacitor size (kvar) depend upon an induction motor's speed; does a motor with larger number of poles have a lower power factor?

- When power factor correction capacitors are used in industries, does a capacitor's power factor rating specify the total reactive power (Q) supplied for all three phases or is it Q supplied per phase?

 

[Baluncore]

Power factor is the end result of the analysis. At the supply frequency, the inductive load current is being largely canceled by the correction capacitor current. The PF of an uncorrected motor will depend on the mechanical load being driven. Rather than considering PF, I think you need to look instead at the fixed inductive characteristics of the different motor configurations.

 

[jim hardy]

Old thread, but interesting question..

does a motor with larger number of poles have a lower power factor?

this would suggest so

source: http://publish.illinois.edu/grainger-ceme/files/2014/06/CEME1109HarleyGeorgiaTech.pdf

though one has to choose his compromises when designing
he could achieve high power factor in a multipole machine by making it large enough to reduce magnetizing current, at the expense of higher cost for material(more iron and copper).

old jim