ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
Photo Editing Software?
by Fridayrack - 12/03/21 05:05 AM
Square D "All-In-One" Panelboard
by NORCAL - 11/30/21 12:48 PM
Where is Everyone?
by luckyshadow - 11/21/21 10:14 AM
It's been an interesting career
by The Watt Doctor - 11/19/21 09:56 AM
Well I am back to stay (nearly 6 years)
by The Watt Doctor - 11/19/21 09:17 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
1 members (Scott35), 13 guests, and 18 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Joined: Jul 2004
Posts: 783
L
LarryC Offline OP
Member
Thought experiment:

Three single phase pole mount transformers 4160/240 CT

High voltage is 4160 Wye, Low votage 120/240 CT delta.

High voltage and low voltage share common neutral/earth.

Car accident isolates neutral from rest of power distribution network. The three 4160 lines are still intact, the earth connection via building bonds still intact.

Q1) If transformers are equally loaded, no shift on high voltage side. Correct?

Q2) Assuming stable transformer loading, no shift on low voltage side too?

Q3) What happens when most of 3 phase loads dissapear, leaving a significant single phase load?

Thanks

LarryC

Joined: Jul 2004
Posts: 9,672
Likes: 7
G
Member
The line to neutral loads will balance, just like in a regular120/240. If one side is more heavily loaded, the magic smoke will be coming out of the other side. Motors on both sides are in danger.


Greg Fretwell
Joined: Jul 2004
Posts: 783
L
LarryC Offline OP
Member
Would the HV "neutral" shift with the unbalance and difference between this "neutral" and the rest of the power company "neutrals" in the area, result in current thru all available paths like the plumbing and the earth itself?

Joined: Jul 2004
Posts: 9,672
Likes: 7
G
Member
If you are talking about losing the neutral on the line side of the pole pigs, it would really depend on where you lived. Some places have a better "ground" than others. If this was metal water piping, all the way back to the pumping station, you might not even notice the neutral was gone. If you are in Florida with plastic piping and sand around the electrodes, you are still going to balance the loads and the neutral will track that ratio. This is where you could be saved by diversity. The more customers you have on the load side of the break, the better chance you have that the loads will balance. It is still going to be pretty unstable.


Greg Fretwell

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
Vlado
Vlado
Croatia
Posts: 28
Joined: February 2011
Top Posters(30 Days)
Admin 3
dsk 2
Popular Topics(Views)
286,517 Are you busy
218,948 Re: Forum
205,072 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5