Medium Voltage Application Guide

More documents

Recommendations

Info

13752.A SWITCHGEAR flux). The second winding generates a current in the secondary load, which is directly proportional to the measured primary current. This method is very accurate with a tolerance in the order of ±0.02%. A zero flux CT can only be used to measure DC primary current. 1 Current to be measured Magnetic circuit 2 3 4 Secondary winding Secondary circuit current Zero flux detection winding Z Current amplifier 5 6 Page 120 Medium Voltage Application Guide 710-12280-00A
Time (s) SWITCHGEAR Protection Devices Protection devices are used in medium voltage distribution systems to protect line and cable feeders, busbar systems, transformers, motors, generators and power factor correction banks. Abnormal conditions can be detected based on secondary current and voltage measurement, or temperature monitoring using thermal devices. When an abnormal condition is detected, correct coordination of the protection devices will rapidly isolate the fault to a specific zone in the system. Older protection devices relied on electromechanical relays to measure system parameters. Modern protection devices are exclusively low consumption, digital, and microprocessor based, with many communication options available. Modern high-end protection devices incorporate many parameter settings along with programmable logic control which provides not only protection functions, but switchgear control and interlocking. Protection devices are primarily covered by IEC 60255-1. Protection functions Overcurrent This is the most widely used form of protection. In a 3-phase power system, all three line currents are measured using current transformers. The secondary output of a 1 A or 5 A current transformer is connected to the current input of a protection device. Within the protection device, analog signals are filtered and sampled before being converted to digital signals for processing. A trip condition occurs if a preset current level is exceeded for a specific time. There are two basic methods of overcurrent protection: Time-overcurrent protection - provides overload protection similar to a bimetallic thermal overload device, except thermal modelling adjusts the trip curve shape to allow for dynamic heating and cooling conditions. If the measured current reaches a point on the overload curve, a trip will occur. Time-overcurrent is also referred to as "inverse" (I) protection Instantaneous overcurrent protection - provides medium level and high level short circuit protection. If a set current level is exceeded for set time period, a trip will occur. This protection is also referred to as definite minimum time (DMT) protection. Devices may combine time-overcurrent and instantaneous overcurrent protection. Time-overcurrent is normally only applied to electrical machines such as transformers and motors, whereas instantaneous overcurrent is applied to cables, busbar systems etc. Overcurrent protection can be directional, which is sometimes used for more advanced selective isolation of faults. Overcurrent protection 1 Time overcurrent (I) Instantaneous overcurrent (DMT) 2 Current (A) 13753.A 710-12280-00A Medium Voltage Application Guide Page 121
Page 1:
Medium Voltage Application Guide
Page 4 and 5:
CONTENTS 4 Switchgear .............
Page 6 and 7:
INTRODUCTION 1 Introduction This re
Page 8 and 9:
03340.B Current Torque MOTORS magne
Page 10 and 11:
Torque Current MOTORS Typical start
Page 12 and 13:
03340.B Current Torque MOTORS 2.2 M
Page 14 and 15:
13190.A Current Torque 13193.A Curr
Page 16 and 17:
MOTORS How does soft start compare
Page 18 and 19:
MOTORS Soft starters Electronic sof
Page 20 and 21:
MOTORS Bypassed VFD installation 1
Page 22 and 23:
13473.A SOFT STARTERS Open loop sof
Page 24 and 25:
SOFT STARTERS 3.2 Benefits Electric
Page 26 and 27:
13490.A 13489.A SOFT STARTERS Snubb
Page 28 and 29:
SOFT STARTERS Enclosed soft starter
Page 30 and 31:
12996.A SOFT STARTERS Local control
Page 32 and 33:
SOFT STARTERS Key Features MVS soft
Page 34 and 35:
SOFT STARTERS Vibration ...........
Page 36 and 37:
SOFT STARTERS MVX Soft Starter Over
Page 38 and 39:
SOFT STARTERS General Technical Dat
Page 40 and 41:
11083.B 11082.B SOFT STARTERS Power
Page 42 and 43:
13015.A 13013.A SOFT STARTERS Soft
Page 44 and 45:
SOFT STARTERS Predictive Maintenanc
Page 46 and 47:
SOFT STARTERS Medium voltage starte
Page 48 and 49:
STAR T STO P RESET INPU TA INPU T B
Page 50 and 51:
Ready R un Trip Local 11081.C SOFT
Page 52 and 53:
13522.A 13521.A 13513.A SOFT STARTE
Page 54 and 55:
09593.A Current SOFT STARTERS AC53
Page 56 and 57:
09678.B Current Torque (% motor ful
Page 58 and 59:
13634.A 13633.A Current (%FLC) Torq
Page 60 and 61:
SOFT STARTERS Example Calculate the
Page 62 and 63:
SOFT STARTERS Operating Sequence NO
Page 64 and 65:
13530.A SOFT STARTERS Typical multi
Page 66 and 67:
SOFT STARTERS AuCom multi-motor sta
Page 68 and 69:
13531.A SOFT STARTERS Slip ring mot
Page 70 and 71:
SOFT STARTERS 3.8 Common standards
Page 72 and 73: 11158.A SWITCHGEAR 4.1 Switchgear C
Page 74 and 75: SWITCHGEAR ANSI-defined switchgear
Page 76 and 77: 11165.A 11163.A SWITCHGEAR 4.2 Stan
Page 78 and 79: 11169.A 11166.A SWITCHGEAR Bus Coup
Page 80 and 81: 11174.A 11173.A SWITCHGEAR Metering
Page 82 and 83: SWITCHGEAR Design Busbar system des
Page 84 and 85: SWITCHGEAR Resonant frequency The b
Page 86 and 87: SWITCHGEAR Interlock scheme 1: Two
Page 88 and 89: SWITCHGEAR Causes of internal arc T
Page 90 and 91: 13716.A Current 13680.A SWITCHGEAR
Page 92 and 93: 11163.A SWITCHGEAR When a withdrawa
Page 94 and 95: 13720.A Percentage DC component SWI
Page 96 and 97: 13722.A Voltage SWITCHGEAR Transien
Page 98 and 99: 13681.A SWITCHGEAR Medium Voltage C
Page 100 and 101: 13684.A Maximum cut-off current (kA
Page 102 and 103: 13688.A 13689.A 13691.A 13690.A 136
Page 104 and 105: SWITCHGEAR IEC Ratings Disconnector
Page 106 and 107: Pre-arcing time (seconds or minutes
Page 108 and 109: SWITCHGEAR Nominal current, In (A)
Page 110 and 111: 13745.A Fuse rating (A) 13697.A Fus
Page 112 and 113: SWITCHGEAR Current Transformers A c
Page 114 and 115: Flux () SWITCHGEAR Exercises 1. A C
Page 116 and 117: SWITCHGEAR Class type Use a meterin
Page 118 and 119: SWITCHGEAR Exercise 2: Protection C
Page 120 and 121: SWITCHGEAR NEMA/IEEE Ratings These
Page 124 and 125: 13761.A 13760.A 13758.A 13759.A SWI
Page 126 and 127: 13754.A SWITCHGEAR Distance This pr
Page 128 and 129: Incomer feeder panel Transformer Mo
Page 130 and 131: SWITCHGEAR Many manufacturers use a
Page 132 and 133: 13766.A SWITCHGEAR Motor Line Induc
Page 134 and 135: Magnitude of overvoltage /p.u. Line
Page 136 and 137: SWITCHGEAR Exercise A 17.5 kV secon
Page 138 and 139: 13807.A 13808.A SWITCHGEAR Power Fa
Page 140 and 141: SWITCHGEAR Exercise Calculate the t
Page 142 and 143: 13812.A SWITCHGEAR Calculations: pe
Page 144 and 145: SWITCHGEAR Step 3: Calculate the eq
Page 146 and 147: 13847.A SWITCHGEAR The calculated s
Page 148 and 149: SWITCHGEAR Transformer internal imp
Page 150 and 151: SWITCHGEAR Exercise For a motor run
Page 152 and 153: SWITCHGEAR The total coefficient fa
Page 154 and 155: SWITCHGEAR Short-time withstand cur
Page 156 and 157: 14009.A SWITCHGEAR Mechanical stren
Page 158 and 159: SWITCHGEAR Resonant frequency The b
Page 160 and 161: Current 13850.A SWITCHGEAR Synchron
Page 162 and 163: 13854.A 13852.A 13853.A SWITCHGEAR
Page 164 and 165: SWITCHGEAR 4.6 Switchgear Inspectio
Page 166 and 167: SWITCHGEAR Commissioning Tools and
Page 168 and 169: SWITCHGEAR 62271-302 High voltage s
Page 170 and 171: 13856.A 13855.A SWITCHGEAR 4.9 IEC
Page 172 and 173:
SWITCHGEAR 4.10 Protection index IP
Page 174 and 175:
SCHEMATIC DIAGRAMS 5 Schematic Diag
Page 176 and 177:
14043.A 14042.A SCHEMATIC DIAGRAMS
Page 178 and 179:
14046.A 14045.A SCHEMATIC DIAGRAMS
Page 180 and 181:
14049.A SCHEMATIC DIAGRAMS 5.5 MVS
Page 182 and 183:
14051.A SCHEMATIC DIAGRAMS 5.6 MVX
Page 184 and 185:
RESOURCES 6 Resources 6.1 Equipment
Page 186 and 187:
CONTENTS Contents Introduction ....
Page 188 and 189:
2. ENVIRONMENTAL SPECIFICATIONS Env
Page 190 and 191:
LOGIC CONTROL CONFIGURATION 3.2 Ope
Page 192 and 193:
LOGIC CONTROL CONFIGURATION 3.6 Met
Page 194 and 195:
SPECIFICATION: MVX Solid State Redu
Page 196 and 197:
1. 1. INTRODUCTION Introduction 1.1
Page 198 and 199:
ENVIRONMENTAL SPECIFICATIONS The eq
Page 200 and 201:
LOGIC CONTROL CONFIGURATION 3.2 Ope
Page 202 and 203:
LOGIC CONTROL CONFIGURATION 3.6 Met
Page 204 and 205:
SPECIFICATION: Power factor Correct
Page 206 and 207:
1 INTRODUCTION Introduction 1.1 Sco
Page 208 and 209:
3 SUPPORT AND SERVICES Support and
Page 210 and 211:
CONTENTS Contents Introduction ....
Page 212 and 213:
2. DOCUMENTATION Documentation 2.1
Page 214 and 215:
3.2.2 MV Equipment a) Circuit break
Page 216 and 217:
ELECTRICAL SUPPLY 9. Circuit breake
Page 218 and 219:
RESOURCES 6.2 Metric/Imperial Conve
Page 220 and 221:
RESOURCES 6.4 Incoterms Internation
Page 222 and 223:
RESOURCES kW Active power unit LRC
show all

Medium Voltage Application Guide

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?