Javascript Disabled Detected

You currently have javascript disabled. Several functions may not work. Please re-enable javascript to access full functionality.

Capacitor Bank On Vfd Output / Soft Starter Output

Started by dip04051978, Dec 18 2008 10:50 AM

Please log in to reply

3 replies to this topic

#1 dip04051978

Intermediate Member

Full Member
20 posts

Location:Anand

Posted 18 December 2008 - 10:50 AM

WHAT WILL HAPPEN IF VFD IS CONNECTED ON MOTOR WHERE ALREADY PF CORRECTION CAPACITOR CONNECTED.
What will be the effect on Soft starter with the same case ??

Back to top

#2 jraef

Posting Freak

Moderator
683 posts

Gender:Male
Location:USA, California

Posted 19 December 2008 - 11:46 PM

QUOTE (dip04051978 @ Dec 18 2008, 02:50 AM) <{POST_SNAPBACK}>

WHAT WILL HAPPEN IF VFD IS CONNECTED ON MOTOR WHERE ALREADY PF CORRECTION CAPACITOR CONNECTED.
What will be the effect on Soft starter with the same case ??

Usually a race between the capacitor or the power switching devices to see which one can fail faster.

"He's not dead, he's just pinin' for the fjords!"

Back to top

#3 dip04051978

Intermediate Member

Full Member
20 posts

Location:Anand

Posted 22 December 2008 - 05:44 AM

Thanks for rpely Jreaf.
We know it is not recommanded to connect capacitor on the output side of the Drive / Softstarter.
But can you please explain in detail how it will fail.

Back to top

#4 marke

Posting Freak

Moderator
2,637 posts

Gender:Male
Location:Christchurch, New Zealand

Posted 23 December 2008 - 12:57 AM

Every time you turn ON the IGBTs in a VFD or the SCRs in a soft starter, they have to carry the charging current to the capacitors which look like a short circuit until charged.
This causes very high currents to flow through the switching device and these high currents damage the switching devices (IGBT SCR)

Best regards,
Mark.