 |
Hello and welcome to LMPForum, like most online communities you must register to view or post in our community, but don't worry this is a simple free process that requires minimal information. Take advantage of it immediately Register Now There are many great features that are not available to guests at LMPForum |
Forgot Password |
  |
Lrc, LRC |
·
·
·
·
·
·
·
·
·
·
·
·
 Jun 5 2009, 06:52 PM
Post
#1
|
|
|
Intermediate Member  Group: Full Member Posts: 15 Joined: 16-December 08 Member No.: 5,027  |
Hello forum members,
I know that the lock rotor current of an inductio motor varies between 7-12 times the flc. My question is as follows: Is the LRC dependent on the mode of starting? Star/delta and DOL application? Thanks. Bob |
 |
 
|
|
Jun 5 2009, 08:55 PM
Post
#2
|
|
|
Posting Freak Group: Moderator Posts: 2,383 Joined: 24-April 02 From: Christchurch, New Zealand Member No.: 1 |
Hello Bob
Yes, the LRC (or LRI) is the current drawn under full voltage starting conditions. If you reduce the voltage, you reduce the current. If you connect a delta motor in star, you are reducing the voltage acros each winding so you reduce the effective LRC also. Best regards, Mark. -------------------- Mark Empson administrator
Skype Contact = markempson | phone +64 274 363 067 LMPForum | LMP Tech Warehouse | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | LMP Software | Mark Empson Website |
|
|
|
 Jun 7 2009, 11:03 AM
Post
#3
|
|
|
Intermediate Member Group: Full Member Posts: 15 Joined: 16-December 08 Member No.: 5,027 |
Thanks Mark, which means that a circuit breaker with a lower magnetic setting could be used instead.
Bob |
|
|
|
|
Jun 7 2009, 07:34 PM
Post
#4
|
|
|
Posting Freak Group: Moderator Posts: 2,383 Joined: 24-April 02 From: Christchurch, New Zealand Member No.: 1 |
Hi Bob
I presume that you are considering an application using a star delta starter. In this case, while the initial current in star is lower, the initial current when you change to delta is commonly higher than the normal delta LRC. This is due to the open transition switching transient. There are other posts on this topic. I would use the same magnetic trip, possibly higher. Best regards, Mark. -------------------- Mark Empson administrator
Skype Contact = markempson | phone +64 274 363 067 LMPForum | LMP Tech Warehouse | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | LMP Software | Mark Empson Website |
|
|
|
|
|
Lo-Fi Version | Time is now: 3rd September 2010 - 07:25 PM |
