Open Circuit Shunt - CR4 Discussion Thread

Home

Products & Services

Engineering News

Standards

Webinars

Engineering Forum

Login

CR4 Home | Electrical Engineering | Electrical Engineering

6 comments

Rate

Comments: Nested

JDriethmuller Member Join Date: Jan 2015 Posts: 8	Open Circuit Shunt 01/21/2015 4:04 AM
	Hi guys this is a follow up to my first question about earth leakage toroid systems. We now have moved both MEN links to upstream of the of the toroids and tested both generators successfully. Both shunts we installed were 24v DC supplied by ABB, the design choice to use 24v was based around not being sure whether if we had a under voltage situation that a 240v shunt would do its job. We always have a 24V DC supply from the batteries to the control panel. ( any comments on this would be appreciated ) The control / display panel has a 6Amp HRC fuse protecting it & we took supply from the protected side to the relay for the shunt. Upon our first test the shunt tripped the main switch but we noticed a nasty smell from the control panel, shunt and we had a blown fuse. Even though the panel stank we found a fuse and got it going again thank god but the shunt was now open circuit. We switched to a 240v shunt and it operated fine. The coil of the shunt is 24v DC or AC, the paperwork is shocking for explanations & you have to decipher pictures. I am not exactly sure what the current draw of the coils are as its not described anywhere on the shunt or paperwork but I would not have thought it was 6 amps. I do not have a part number but its a shunt for a 3 pole ABB main switch, 400amp rated. Did we just get a bung shunt or did we make another make in our install? any thoughts appreciated
	Register to Reply

Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Join CR4, The Engineer's Place for News and Discussion!

lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#1 Re: Open Circuit Shunt 01/21/2015 8:54 AM
	HIRE A COMPETENT ENGINEER!!!!
	Register to Reply

gringogreg Guru Join Date: Dec 2007 Location: Haverhill, MA Posts: 1149 Good Answers: 151	#2 In reply to #1 Re: Open Circuit Shunt 01/21/2015 9:36 AM
	You need more fiber in your diet. Did you read the OP's previous post " I am a young electrician from Australia trying to learn more about what I am doing." He just trying to understand the theory behind the work he is being told to do. Perhaps he needs a better supervisor, one that is willing to explain the reasoning for his instructions. __________________ The older I am, the better I used to be
	Register to Reply

lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#3 Re: Open Circuit Shunt 01/21/2015 11:25 AM
	My fault. I had just read the "please do my job for me and size my mystery cables post" prior to this one. Sorry.
	Register to Reply

jack of all trades Guru Join Date: Sep 2006 Location: Auckland, New Zealand Posts: 8777 Good Answers: 376	#4 Re: Open Circuit Shunt 01/21/2015 1:34 PM
	Sounds like a faulty shunt, but check the 24V power supply and connections going to the shunt just to make sure you weren't overloading it, then get a new replacement. The parts should have enough marking on them to give you an idea what they are and hence if they are suitable for the control voltage you are using. __________________ jack of all trades
	Register to Reply

spades Guru Join Date: Aug 2014 Location: Port Macquarie N.S.W. Australia Posts: 1071 Good Answers: 225	#5 Re: Open Circuit Shunt 01/21/2015 10:42 PM
	Glad to see you fixed the first problem. Without sighting an "as wired circuit diagram" one can only guess at what went wrong with the 24v shunt release unit. My first thought is that it is unlikely to have been a faulty shunt. Is it possible that you somehow injected more than 24v onto that shunt coil? The fact that the coil and the fuse both went - along with the pleasant aroma - tends to point towards excess voltage being applied. You say that you had 2 of these systems installed - did you have the same trouble with both of them?
	Register to Reply

JDriethmuller Member Join Date: Jan 2015 Posts: 8	#6 In reply to #5 Re: Open Circuit Shunt 01/22/2015 12:45 AM
	The answers are what I expected, I thought it would be hard to speculate but I was wondering if we missed something obvious. It sounds silly I know but honestly the ABB paperwork was hopeless and I could not see any current draw written on the shunt. We have some paperwork regarding the generator because we had to work out how to perform the engine shut down via the backup relay. It was a matter of grounding a particular input cable into the control panel. We definitely had 24V DC as well. My supervisor is not a bad electrician but lacks a little of the theory behind some things we install. He has been in business for 30 years and has done well but I like to ask a lot of questions when I don't know or understand what I am installing and they cannot seem to answer a few. And the second install with a 24v DC shunt worked perfectly, it was just that one. Thanks anyway guys for comments.
	Register to Reply

Copy to Clipboard

Users who posted comments:

gringogreg (1); jack of all trades (1); JDriethmuller (1); lyn (2); spades (1)

	Got Something to Say?
	Ask a Question Start a Discussion

	Search this Forum
	Electrical Engineering: Go

CR4 Sections

	Aerospace
	BioMech & BioMed
	Chemical & Material Science
	Civil Engineering
	Communications & Electronics
	Education and Engineering Careers
	Electrical Engineering
	General Discussion
	Instrumentation
	Manufacturing
	Mechanical Engineering
	New Technologies & Research
	Software & Programming
	Sustainable Engineering
	Transportation

	Site Directories
	Forum Directory Blog Directory User Group Directory RSS Feeds CR4 Rules of Conduct CR4 FAQ Site Glossary Who's Online (81 right now) Show Members