×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

MV Vacuum Contactors & Break Time
3

MV Vacuum Contactors & Break Time

MV Vacuum Contactors & Break Time

(OP)
I find some of the VCU makes have break times like 400 milliseconds (Siemens 3TL8).
I am used to seeing break times of the order of 50ms for the HV/MV switchgear. Any thoughts!!
Thanks in advance.

RE: MV Vacuum Contactors & Break Time

50ms could be for vacuum circuit breakers not contactors. Contactors are inherently slower than breakers.  

RE: MV Vacuum Contactors & Break Time

(OP)
rbulsara,
Why is it so!
The contactors have less gap between the contacts and so I thought less opening time they should have. Is it because of the necessity to be compact!

Thanks for your response.

RE: MV Vacuum Contactors & Break Time

2
The contact separation springs on breakers are several orders of magnitude larger (and stronger) than the separation springs on contactors.  Breakers have springs similar to those used automotive suspensions and contactors have very small low energy coil or leaf springs.

RE: MV Vacuum Contactors & Break Time

raghun:
Laplacian answered the question. Breakers have special mechanism and are "made" to interrupt fault currents, contactors are not. Contactors depend on upstream fuse or breaker for short circuit protection.

Get yourself familiarized with breaker and contractor construction.

RE: MV Vacuum Contactors & Break Time

Very common misconceptions. People use VCBs quite often as contactors, then assume that contactors are the same as VCBs. The bottles inside are often the same, but the difference is in the mechanism.

Nice responses Laplacian and rbulsara.  


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln  
For the best use of Eng-Tips, please click here -> FAQ731-376: Eng-Tips.com Forum Policies  

RE: MV Vacuum Contactors & Break Time

raghun:

Firstly, we were only responding to what you posted (400ms). It may be possible to have fast vacuum contractor. However you may want to ask clarification from the manufacturer on the significance of "100ms minimum closing command for the solenoid".

Regardless, not sure what is your objective or issue but a contactor is no substitute for a breaker.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources