How to Size the Correct Protection Px CT for Transformer Fault

2 comments

Rate

liukawa Associate Join Date: Jun 2009 Location: Singapore Posts: 36	How to Size the Correct Protection Px CT for Transformer Fault 01/30/2015 12:24 PM
	Hi Guys, I have bought a protection class Px CT with the following details : 1) CT Ratio : 500/5A Knee Point Voltage > 80V Resistance Of CT < 0.23 ohms Exciting Current < 0.15A This Protection Px CT is used in our switchgear as a transformer feeder panel. The max fault current under short circuit condition going through the transformer will reach up to 21kA. As such, I would like to know whether will my protection Px CT saturate under the max fault condition? How do we perform the calculation to check whether will my CT saturate? Appreciate if any kind souls can help a.s.a.p as we are undergoing commissoning currently. Thanks ! __________________ There is no limit towards how much one can learn.
	Register to Reply

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

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!

RAMConsult Guru Join Date: May 2007 Location: NYC metropolitan area. Posts: 3230 Good Answers: 444	#1 Re: How to size the correct Protection Px CT for transformer fault 01/30/2015 12:36 PM
	I hate to be the bearer of bad news, but you're supposed to check that before you buy it! The other thing you need is the total burden on the CT including all relays, meters, instrumentation, and don't forget the round trip wiring. Ready, fire, aim is not good engineering practice. __________________ “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
	Register to Reply

lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#2 Re: How to size the correct Protection Px CT for transformer fault 01/30/2015 12:50 PM
	You are a fatality waiting to happen. Please go back to school and get a proper education. Then PURCHASE the applicable code books and learn how to apply them. All your questions are sadly lacking in knowledge, and yet you are at a commissioning of equipment about which you KNOW NOTHING??????????? Especially the fact that you have no idea how to hook two 12V batteries into a system. You are a danger to your unwitting customers. Also, what you are doing is unethical and dishonest! You should not be allowed at the worksite. Hire a tutor until such time as you have gained sufficient knowledge to not be a danger to society.
	Register to Reply Score 1 for Good Answer

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!

	Got Something to Say?
	Ask a Question Start a Discussion

	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 (71 right now) Show Members