May 19, 2003 #1 Darrick Electrical Oct 7, 2002 5 Anyone know the required standard for IDMT Relay Curve? What is the Equation/Formular? Thanks.
May 19, 2003 #2 johnspark Electrical Jul 19, 2001 18 Darrick, there are many many IDMT curves about. You need to ask yourself the question: which one do I want to use? cheers Johnspark Upvote 0 Downvote
Darrick, there are many many IDMT curves about. You need to ask yourself the question: which one do I want to use? cheers Johnspark
May 19, 2003 Thread starter #3 Darrick Electrical Oct 7, 2002 5 I am referring to the 3/10 curve. I would like to check using manual calculation say for a required setting after reading off the graph. Upvote 0 Downvote
I am referring to the 3/10 curve. I would like to check using manual calculation say for a required setting after reading off the graph.
May 20, 2003 1 #4 5P10 Electrical May 18, 2003 5 By 3/10, I believe you are talking about the Normal Inverse (NI) curve. Formulas below:- t = (k.B)/((I/Is)^a - 1) where t = operating time (sec) k = TMS (time multiplier settings) I = measured current value (A) Is= set current value a B Normally Inverse 0.02 0.14 Very Inverse 1.0 13.5 Extremely Inverse 2.0 80.0 Long Time Inverse 1.0 120.0 NI = 3/10, VI = 1.2/10, EI = 0.8/10, LTI = 12/10. You can also refer to BS142.1966 or IEC 255-4. Upvote 0 Downvote
By 3/10, I believe you are talking about the Normal Inverse (NI) curve. Formulas below:- t = (k.B)/((I/Is)^a - 1) where t = operating time (sec) k = TMS (time multiplier settings) I = measured current value (A) Is= set current value a B Normally Inverse 0.02 0.14 Very Inverse 1.0 13.5 Extremely Inverse 2.0 80.0 Long Time Inverse 1.0 120.0 NI = 3/10, VI = 1.2/10, EI = 0.8/10, LTI = 12/10. You can also refer to BS142.1966 or IEC 255-4.
May 20, 2003 #5 piterpol Electrical Jan 12, 2003 35 For more information see: http://www.selinc.com/instruction_manual/551/551_4.pdfRefer to pages 4-2 to 4-6 for different US and IEC inverse-time curves equations and graphics. Upvote 0 Downvote
For more information see: http://www.selinc.com/instruction_manual/551/551_4.pdfRefer to pages 4-2 to 4-6 for different US and IEC inverse-time curves equations and graphics.
May 20, 2003 Thread starter #6 Darrick Electrical Oct 7, 2002 5 Thank you so much for the information guys. Been really helpful. Upvote 0 Downvote
May 20, 2003 #7 piterpol Electrical Jan 12, 2003 35 Oops! My former post has a server error. Let me try again. http://www.selinc.com/instruction_manual/551/551_04.pdf Upvote 0 Downvote
Oops! My former post has a server error. Let me try again. http://www.selinc.com/instruction_manual/551/551_04.pdf
