Why We Used Relay Curve,SI,VI,EI For Relay Setting?

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SATCHHIKARA Active Contributor Join Date: Jan 2010 Posts: 19	Why We Used Relay Curve,SI,VI,EI For Relay Setting? 10/15/2010 10:16 PM
	IN MY PLANT FOLLOWING CURVE ARE USED IN RELAY SETTING SIMPLE INVERSE, VERY INVERSE ,E I CVRVE ARE USED, PLEASE GIVE DETAIL. MY PLANT POWER DISTRUBUTION 33KV,6.6 KV,415 KV.
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Mizuti Guru Join Date: Jun 2010 Location: New York Posts: 972 Good Answers: 23	#1 Re: Why We Used Relay Curve,SI,VI,EI For Relay Setting? 10/15/2010 10:37 PM
	The first trick is turning off the Caps Lock, or stop holding down 'shift'. Whichever you're doing. __________________ The first law of thermodynamics is you do NOT talk about thermodynamics.
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mountk2 Power-User Join Date: Jun 2010 Posts: 348 Good Answers: 10	#2 Re: Why We Used Relay Curve,SI,VI,EI For Relay Setting? 10/16/2010 3:14 AM
	A simple explanation is to create backup function to instantaneous relays, without compromising on system stability by avoiding delayed tripping. __________________ Knowledge sharing is a WIN-WIN situation
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PeterT Guru Join Date: May 2010 Location: Liverpool, NY Posts: 961 Good Answers: 131	#3 Re: Why We Used Relay Curve,SI,VI,EI For Relay Setting? 10/18/2010 9:16 AM
	The different time characteristic curves are used to allow relays to be coordinated with each other, with other protective devices (fuses for example), and with equipment to be protected (transformer thermal damage curves, motor damage curves, etc.). The characteristics are chosen to give the most flexibility and selectivity between relays, so that (hopefully) the one nearest the fault will trip first, before a more distant relay takes out more of your facility's electrical system. __________________ To get the right answers, first you need to ask the right questions.
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electricalexpert65 Guru Join Date: Oct 2009 Posts: 2061 Good Answers: 169	#4 Re: Why We Used Relay Curve,SI,VI,EI For Relay Setting? 10/18/2010 9:17 AM
	If you are an industry with short cable lengths, please go for Simple Inverse Curve only. Very Inverse is used for long cable lengths and Extremely Inverse for loads with high peak currents.
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