Dave Bradley, PE, LEED AP Understanding Time Current Curves and Coordination Studies Restricted © Siemens Industry, Inc. 2015 All rights reserved. usa.siemens.com In This Elective • Time Current Curve Basics • Uses of Time Current Curves • Coordination Study Basics Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 2 How will this help me next week? • Better understanding circuit breakers • Understand what TCCs can be used for, and for what they shouldn’t be used • Understand general differences between coordination and Selective Coordination Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 3 Where did it all start? Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 4 In the beginning... Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 11 Inverse Time Element Current Time Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 12 How It Works Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 13 How it Works – Thermal Magnetic Tripping “foot” Contacts Load Connection Line Connection Electromagnet Bi-Metallic Strip Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 14 How it Works – Solid State Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 15 Time Current Curves Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 16 0 TIME How to Show a Wide Range on a Small Paper 0 CURRENT Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 17 Logarithmic Time 1,000s 100s 10s 1s 100ms 10ms Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 18 Logarithmic Current 10A 100A 1,000A 10,000A 100,000A Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 19 Time Current Curves in the Real World 14 Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 20 Time Current Curves in the Real World 20 14 Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 21 Time Current Curves in the Real World 20 M 14 10HP 14 Inrush Currents • 20x for ½ cycle • 4-8x for several seconds Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 22 Time Current Curves in the Real World 20 30 M 14 10HP 14 Inrush Currents • 20x for ½ cycle • 4-8x for several seconds Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 23 Time Current Curves in the Real World 36 30kVA 30 20 M 14 10HP 14 Inrush Currents • Worst case: 14x + • Average: 5x for a couple of cycles Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 24 Time Current Curves in the Real World 90 36 30kVA 30 20 M 14 10HP 14 Inrush Currents • Worst case: 14x + • Average: 5x for a couple of cycles Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 25 Time Current Curves in the Real World 250 90 100 30kVA 20 36 30 M 14 Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 26 14 10HP Time Current Curves – Thermal Magnetic 1985 Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 27 2006 Time Current Curve Details Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 28 Changes to New TCCs OLD NEW Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 29 Molded Case Switches Motor Circuit Protectors Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 30 Thermal Magnetic vs Electronic Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 31 Time Current Curves – Electronic Long Time • Handle Rating • Overloads Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 32 Time Current Curves – Electronic Long Time Delay • Normal Inrush Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 33 Time Current Curves – Electronic Short Time • Coordination • Curve Matching Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 34 Time Current Curves – Electronic Short Time Delay • Coordination • Curve Matching Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 35 Time Current Curves – Electronic Instantaneous • Faults Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 36 Uses of TCCs Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 37 Time Current Curve Software – EasyTCC Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 38 Time Current Curve Software – SKM Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 39 Coordination Studies Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 40 Uses of TCCs - Coordination Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 41 Selectivity Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 43 Coordination 0.1s 800 250 100 Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 44 Selective Coordination 0.01s 800 260 100 Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 45 Behavior in the Field Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 46 Uses of TCCs For application and coordination purposes only. Based on 40°C ambient cold start. Connected with 4 feet of rated wire (75°C) per terminal. Tested in open air with current in all poles. Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 47 Uses of TCCs - Operation and Testing Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 48 Uses of TCCs - Operation and Testing Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 49 40ºC 25ºC NEMA AB-4 (104ºF) Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 50 Same Device, Different Settings The purple time current curve (TCC) reflects how the breaker is set when it leaves the plant The blue TCC shows one possibility for how the breaker could be set. This leave a fairly wide range of possible settings Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 55 Effect of Incorrect Settings Add in the feed to the air conditioner and you can see why the main breaker tripped out Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 56 Summary Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 58 Summary • You know how loads and circuit breakers interact, and how the time current curve shows that • You understand what TCCs can be used for, and for what they shouldn’t be used • You can now better address initial questions about breaker performance in the field • You know the general differences between Coordination and Selective Coordination Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 59 Questions? Restricted © Siemens Industry, Inc. 2015 All rights reserved. Page 60
