 |
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 |
  |
Restart Of Induction Motor, Starting current in two different situations |
·
·
·
·
·
·
·
·
·
·
·
·
 Apr 11 2009, 07:53 AM
Post
#1
|
|
|
Junior Member  Group: Members Posts: 4 Joined: 3-August 07 From: INDIA Member No.: 3,571  |
If an induction motor is restarted before its rotor stop rotating, then what will be the amount of current drawn?
Is this current will be the same as motor starting current? -------------------- Regads,
Bonny |
 |
 
|
|
Apr 15 2009, 03:22 PM
Post
#2
|
|
 Senior Member Group: Full Member Posts: 213 Joined: 15-March 05 From: Milan, Italy Member No.: 1,068 |
QUOTE (bonny @ Apr 11 2009, 08:53 AM)  If an induction motor is restarted before its rotor stop rotating, then what will be the amount of current drawn? Is this current will be the same as motor starting current? bonny, it is a favourable situation. If the motor is restarted when the speed is high, slip will be low and restarting current will be a little higher than nominal current. If the motor is restarted when the speed is medium, slip will be medium and restarting current will be 2 to 4 times the nominal current. If the motor is restarted when the speed is low, slip will be high and restarting current will be a little bit less than normal locked-rotor current. Regards Mario -------------------- |
|
|
|
|
Apr 16 2009, 07:17 PM
Post
#3
|
|
|
Posting Freak Group: Moderator Posts: 2,383 Joined: 24-April 02 From: Christchurch, New Zealand Member No.: 1 |
In addition to Mario's reply, there is one other consideration.
When the motor is running, there is a rotating magnetic field in the stator which is created by the applied voltage. This induces a rotor current that is dependent on the slip. When the stator voltage is removed, there is still rotor current which will decay at a rate determined by the rotor time constant. If the stator voltage is reapplied while there is residual rotor current, there will be a transient current and torque which is dependent on the magnitude of the rotor current and the phase difference between the rotor current and the stator voltage at the instant of reconnection. Typically, this occurs within 0.5 seconds of switch off, so if you have a minimum OFF time of 1 second or more, the "auto reclose" effect will not occur. 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 |
|
|
|
|
Similar Topics
| Topic Title | Replies | Topic Starter | Views | Last Action | |||
|---|---|---|---|---|---|---|---|
 |
2 | GGOSS | 5,167 | 28th July 2003 - 05:46 AM Last post by: GGOSS |
|||
|
2 | marke | 7,765 | 4th July 2009 - 05:27 AM Last post by: marke |
|||
|
0 | marke | 6,108 | 11th June 2002 - 10:34 PM Last post by: marke |
|||
|
1 | marke | 4,332 | 7th December 2009 - 10:32 AM Last post by: Broshi |
|||
|
0 | marke | 3,031 | 12th June 2002 - 09:24 AM Last post by: marke |
|||
|
Lo-Fi Version | Time is now: 7th September 2010 - 04:17 PM |
