PS Class CT Knee Point Voltage Clarification

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subhakanta Participant Join Date: Jun 2014 Posts: 1	PS Class CT Knee Point Voltage Clarification 06/01/2014 5:26 AM
	Dear Sir, I am having doubt on PS class CT. My question is: "For a certain PS class CT of Vk >= 220V, Ie<= 30mA @ Vk/2. hence what will be the Ie at Vk, when we will conduct knee point test on the PS class CT by gradually increase in voltage from 0V to 242 Volt i.e upto 110% of rated Vk." Again what is acceptance criteria of the knee point test & excitation current as per standard practice.
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lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#1 Re: PS Class CT Knee Point Voltage Clarification 06/01/2014 8:49 PM
	A simple search got About 224,000,000 results (0.58 seconds) is it so hard to type "PS class CT" into a search engine? Knee Point Voltage of Current Transformer PS Class ...
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Rajesh52 Associate Join Date: Jun 2019 Posts: 50 Good Answers: 1	#4 In reply to #1 Re: PS Class CT Knee Point Voltage Clarification 06/27/2019 9:33 AM
	Easy Explanation with examples Knee Point Voltage Calculation of PS class CT
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raghun Power-User Join Date: Jan 2010 Location: Hyderabad Posts: 343 Good Answers: 22	#2 Re: PS Class CT Knee Point Voltage Clarification 06/02/2014 10:21 AM
	CT with Ie of 30mA at Vk/2 will have more than 60mA at Vk. This because as the CT voltage approaches the knee point, the exciting current increases rapidly. The Vk itself is defined as the point where 10% increase in voltage requires 50% increase in the Ie. This way, the Ie at Vk can be as high as 90mA (60+30). Having said that Ie at Vk/2 is relevant in differential protection (based on high impedance principle) setting calculations and no such significance is attached to the Ie at Vk. __________________ Raghunath
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Rajesh52 Associate Join Date: Jun 2019 Posts: 50 Good Answers: 1	#3 In reply to #2 Re: PS Class CT Knee Point Voltage Clarification 06/27/2019 9:29 AM
	https://sdvelectrical.blogspot.com/2018/09/how-to-calculate-knee-point-voltage-of.html
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lyn (1); raghun (1); Rajesh52 (2)

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