ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
Linear Power Supply Quits Under Load
by sabrown. 10/17/18 05:06 PM
220/230/240V 60Hz Systems
by dsk. 10/17/18 01:25 PM
PLC/HMI Enclosure C2, D1
by ghost307. 10/16/18 03:31 PM
Tingle off the water spigot
by dsk. 10/15/18 02:36 PM
New in the Gallery:
What is this for?
Plug terminals
Who's Online Now
0 registered members (), 34 guests, and 25 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
transformer grounding #165690
07/03/07 11:57 AM
07/03/07 11:57 AM
L
lite bulb  Offline OP
Member
Joined: Feb 2006
Posts: 78
wilm,de.
a 480-120/240 50kva dry transformer, i am doing the bonding in the trans. do i ground the trans. frame with the 480 ground and remove the 120/240 strap to the frame. all raceways are pvc with on the 480 side i have 2 phases and a ground. also this trans is mounted on a portable plant with the 120/240 volt panel, the trans and panel are on the same steel frame. what is the proper grounding and bonding.

2017 / 2014 NEC & Related Books and Study Guides
Re: transformer grounding [Re: lite bulb] #165701
07/03/07 03:36 PM
07/03/07 03:36 PM
E
earlydean  Offline
Member
Joined: Dec 2003
Posts: 751
Griswold, CT, USA
Leave the strap to the frame in place.

Bond the green wire from the 480 volt side and the green wire on the 120/240 side and the building steel and any metal water pipes in the vicinity served by the secondary to the enclosure. the strap will connect the equipment grounding system to the neutral connection of the transformer.

The objective here is to clear any ground faults by ensuring a low impedance path back through the equipment ground to the neutral connection at the transformer.

On the 480 volt side, the equipment grounding conductor needs to also be connected to the enclosure to create a low impedance path back to the 480 volt distribution center, then to the service and back to the utility transformer to clear any faults to the transformer enclosure.

We cannot clear any ground faults without a complete low impedance path through the equipment grounding system.


Earl
Re: transformer grounding [Re: earlydean] #165713
07/03/07 08:13 PM
07/03/07 08:13 PM
L
lite bulb  Offline OP
Member
Joined: Feb 2006
Posts: 78
wilm,de.
thanks for the help

Re: transformer grounding [Re: lite bulb] #165714
07/03/07 11:02 PM
07/03/07 11:02 PM
R
resqcapt19  Offline
Member
Joined: Nov 2000
Posts: 2,148
IL
Make sure that the neutral on the secondary side is bonded to a grounding electrode system and to the EGCs for the loads. Many of the bonding straps in the transformer only bond the frame of the transformer to the case. Sometimes they bond the secondary neutral, but that is somewhat rare nowdays.
Don


Don(resqcapt19)

Featured:

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

 

Member Spotlight
Potseal
Potseal
Saskatchewan
Posts: 264
Joined: February 2013
Show All Member Profiles 
Top Posters(30 Days)
sparky 11
Popular Topics(Views)
250,393 Are you busy
187,999 Re: Forum
177,567 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.024s Queries: 15 (0.005s) Memory: 0.9601 MB (Peak: 1.0936 MB) Zlib enabled. Server Time: 2018-10-18 18:35:02 UTC