ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Video: Inventor of the GFCI self-testing shocks
by Bill Addiss. 01/17/18 11:11 PM
FPE in Germany
by HotLine1. 01/17/18 07:07 PM
VDE 0100 to introduce AFCIs
by LongRunner. 01/17/18 10:32 AM
Fujifilm Recalls Power Adapter Wall Plugs
by Admin. 01/16/18 07:04 PM
Air Compressor feeder conductor sizing
by Potseal. 01/15/18 09:08 PM
New in the Gallery:
Housebilding DIY wiring
SE cable question
Who's Online Now
0 registered members (), 14 guests, and 14 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
tie breakers #28809
08/31/03 01:49 PM
08/31/03 01:49 PM
E
Eandrew  Offline OP
Member
Joined: May 2002
Posts: 68
seattle, wa, usa
does anyone know the purpose of tie breakers in switchgear.

Lets say you have a 4000 amp tie breaker ( with a spring loaded handle) between two 3000 amp switchboard panels (each 3000 amp switchboard section housing about 600 amp feeder breakers. Why is this tie breaker connected via copper bussing in the switchgear necessary?

Work Gear for Electricians and the Trades
Re: tie breakers #28810
08/31/03 02:56 PM
08/31/03 02:56 PM
B
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
It is likely that the fault duty is too high for insulated cables to withstand without damage. Properly braced busbars may have been specified particularly for the increased fault current when the tie breaker is closed. The fault duty effectively doubles in that situation—with three breakers closed, two transformers are then operating “in parallel”.




[This message has been edited by Bjarney (edited 08-31-2003).]

Re: tie breakers #28811
08/31/03 07:59 PM
08/31/03 07:59 PM
R
Ron  Offline
Member
Joined: Mar 2002
Posts: 582
White Plains, NY
Main-tie-main switchgear is very common in critical facilities. Depending on the application, each of the mains is designed to carry half of the total swgr load on a normal day. In the event of a failure of one source, the main breaker on the "bad" source is opened, then the tie is closed for the "good" main to carry the full load of the SWGR.
Sometimes I design in a main-tie-tie-main. This allows maintenance access to either side of the tie without any live bus to contend with.


Ron
Re: tie breakers #28812
08/31/03 10:51 PM
08/31/03 10:51 PM
W
Winchester EE  Offline
Junior Member
Joined: Aug 2003
Posts: 9
St. Louis
In the 8 years I've been with my current company, we have used our tie breakers more than once. I think they are a good investment for a company.

We melt copper in large induction furnaces which will "freeze up" if you leave power off for too long. When a main lead blows off the 34Kv, we can tie into a secondary incoming line.


Please buy American made Winchester ammunition! Business is slowly going overseas!
Re: tie breakers #28813
09/02/03 06:47 AM
09/02/03 06:47 AM
F
fireftr  Offline
Member
Joined: Jan 2002
Posts: 15
Bucyrus Ohio Usa
At my plant we have 6 indoor substations that we can tie together in case of a xfmr failure in one of them. We have used it a couple times here in the last few years after a xfmr failure. We also use the Kirk key sytem to avoid any kind of mix up when tying subs together.


Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
watersparkfalls
watersparkfalls
Washington...Not DC
Posts: 222
Joined: March 2005
Show All Member Profiles 
Top Posters(30 Days)
sparky 22
Admin 20
Potseal 13
Popular Topics(Views)
243,530 Are you busy
180,334 Re: Forum
170,823 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.020s Queries: 14 (0.003s) Memory: 0.9665 MB (Peak: 1.1068 MB) Zlib enabled. Server Time: 2018-01-18 05:29:57 UTC