9424200996
84-5
BE1-11
m
Settings Calculation Examples
System Parameters - Sensing Transformers
Phase CT Ratios
The motor manufacturer data for full-load amps (FLA) is 363 A under normal running conditions. Select
phase CTs so that the FLA is 50 percent or greater than the rated phase CT primary current. To minimize
CT saturation, select the phase CT primary current so the FLA is 100 percent of the phase CT primary or
slightly less, never more. IEEE states that “CT saturation is minimized by keeping burdens low (especially
the dc resistive component), by using high-ratio current transformers, and by selecting current
transformers with a high knee-point (saturation) voltage.” (IEEE Std C37.96-2000,
IEEE Guide for AC
Motor Protection
). CTs with a ratio of 80 (400:5) are used in this application example. The secondary
current measured by the BE1-11
m
is 4.54 A when the motor is at full load. Use Equation 84-1 to calculate
the secondary full load amps. A CT with an accuracy class of C400 provides a satisfactory knee-point
voltage for the motor FLA. Enter 80 for CT ratios on the System Parameters, Sensing Transformers
screen shown in Figure 84-5.
363
𝐴𝐴
(
𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹
𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿
𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴
)
80 (
𝐶𝐶𝐶𝐶
𝑅𝑅𝐿𝐿𝑅𝑅𝑅𝑅𝐿𝐿
)
= 4.54
𝐴𝐴
𝐴𝐴𝑠𝑠𝑠𝑠𝐿𝐿𝑠𝑠𝐿𝐿𝐿𝐿𝑠𝑠𝑠𝑠
Equation 84-1. Secondary Full Load Amps
Phase VT Setup
In this example, the phase VT connection is 3-wire, delta. The system voltage is 4 kV. The phase VT ratio
is calculated in Equation 84-2.
𝑆𝑆𝑠𝑠𝐴𝐴𝑅𝑅𝑠𝑠𝐴𝐴
𝑉𝑉𝐿𝐿𝐹𝐹𝑅𝑅𝐿𝐿𝑉𝑉𝑠𝑠
𝑃𝑃−𝑃𝑃
𝑅𝑅𝑠𝑠𝐹𝐹𝐿𝐿𝑠𝑠
𝑁𝑁𝐿𝐿𝐴𝐴𝑅𝑅𝑠𝑠𝐿𝐿𝐹𝐹
𝑉𝑉𝐿𝐿𝐹𝐹𝑅𝑅𝐿𝐿𝑉𝑉𝑠𝑠
𝑃𝑃−𝑃𝑃
=
4000
𝑉𝑉
120
𝑉𝑉
= 33.32
Equation 84-2. Phase VT Ratio
Use the Settings Explorer in BESTCOMS
Plus
to navigate to the System Parameters, Sensing
Transformers screen shown in Figure 84-5. Set Phase VT Ratio to 33.20 and set Phase VT Connection to
3W-D.
Figure 84-5. System Parameters, Sensing Transformers Screen
Summary of Contents for BE1-11m
Page 8: ...vi 9424200996 Revision History BE1 11m...
Page 12: ...x 9424200996 Contents BE1 11m...
Page 21: ...9424200996 1 9 BE1 11m Introduction Figure 1 1 Style Chart...
Page 22: ...1 10 9424200996 Introduction BE1 11m...
Page 40: ...3 6 9424200996 Controls and Indicators BE1 11m Figure 3 3 Front Panel Display Setup Screen...
Page 54: ...5 6 9424200996 Phase Undervoltage 27P Protection BE1 11m...
Page 56: ...6 2 9424200996 Negative Sequence Voltage 47 Protection BE1 11m...
Page 61: ...9424200996 7 5 BE1 11m Phase Overvoltage 59P Protection Figure 7 3 Overvoltage Settings Screen...
Page 62: ...7 6 9424200996 Phase Overvoltage 59P Protection BE1 11m...
Page 68: ...8 6 9424200996 Auxiliary Overvoltage 59X Protection BE1 11m...
Page 80: ...12 4 9424200996 Instantaneous Overcurrent 50 Protection BE1 11m...
Page 84: ...13 4 9424200996 Breaker Failure 50BF Protection BE1 11m...
Page 92: ...14 8 9424200996 Inverse Overcurrent 51 Protection BE1 11m...
Page 105: ...9424200996 18 3 BE1 11m Power Factor 55 Protection Figure 18 2 Power Factor Settings Screen...
Page 106: ...18 4 9424200996 Power Factor 55 Protection BE1 11m...
Page 110: ...19 4 9424200996 Resistance Temperature Detector 49RTD Protection BE1 11m...
Page 118: ...20 8 9424200996 Thermal Curve 49TC Protection BE1 11m...
Page 122: ...22 2 9424200996 Starts per Time Interval 66 Protection BE1 11m...
Page 124: ...23 2 9424200996 Restart Inhibit Protection BE1 11m...
Page 140: ...28 4 9424200996 Breaker Control Switch 101 BE1 11m...
Page 148: ...29 8 9424200996 Setting Groups BE1 11m...
Page 156: ...30 8 9424200996 Metering BE1 11m Figure 30 11 RTD Meter Screen...
Page 158: ...31 2 9424200996 Digital Points BE1 11m Figure 31 2 Digital Points Monitor Screen...
Page 177: ...9424200996 34 5 BE1 11m Motor Reporting Figure 34 9 Learned Motor Data Screen...
Page 178: ...34 6 9424200996 Motor Reporting BE1 11m...
Page 184: ...35 6 9424200996 Alarms BE1 11m...
Page 186: ...36 2 9424200996 Differential Reporting BE1 11m...
Page 196: ...38 4 9424200996 Demands BE1 11m...
Page 198: ...39 2 9424200996 Load Profile BE1 11m...
Page 208: ...41 6 9424200996 Trip Circuit Monitor 52TCM BE1 11m...
Page 212: ...42 4 9424200996 Fuse Loss 60FL BE1 11m...
Page 218: ...43 6 9424200996 BESTnet Plus BE1 11m Figure 43 8 Power Quality Page...
Page 221: ...9424200996 44 3 BE1 11m Mounting Figure 44 3 Case Side Dimensions...
Page 235: ...9424200996 45 5 BE1 11m Terminals and Connectors Figure 45 7 Example of Reversed CT Polarity...
Page 236: ...45 6 9424200996 Terminals and Connectors BE1 11m...
Page 269: ...9424200996 48 15 BE1 11m BESTlogic Plus Figure 48 4 Logic Page 1 for Default Logic...
Page 288: ...49 10 9424200996 Communication BE1 11m Figure 49 14 Modbus Mapping Screen...
Page 306: ...52 4 9424200996 Device Information BE1 11m...
Page 314: ...53 8 9424200996 Configuration BE1 11m Figure 53 3 Display Units Screen...
Page 318: ...54 4 9424200996 Introduction to Testing BE1 11m...
Page 330: ...56 6 9424200996 Commissioning Testing BE1 11m...
Page 336: ...58 4 9424200996 Phase Undervoltage 27P Test BE1 11m...
Page 340: ...59 4 9424200996 Phase Overvoltage 59P Test BE1 11m...
Page 352: ...60 12 9424200996 Auxiliary Overvoltage 59X Test BE1 11m...
Page 360: ...61 8 9424200996 Frequency 81 Test BE1 11m...
Page 364: ...62 4 9424200996 Instantaneous Undercurrent 37 Test BE1 11m...
Page 376: ...63 12 9424200996 Instantaneous Overcurrent 50 Test BE1 11m...
Page 396: ...65 16 9424200996 Inverse Overcurrent 51 Test BE1 11m...
Page 408: ...67 6 9424200996 Power 32 Test BE1 11m...
Page 412: ...68 4 9424200996 Loss of Excitation Reverse Var Based 40Q Test BE1 11m...
Page 426: ...70 10 9424200996 Thermal Curve 49TC Test BE1 11m...
Page 432: ...72 4 9424200996 Starts per Time Interval 66 Test BE1 11m...
Page 436: ...73 4 9424200996 Restart Inhibit Test BE1 11m...
Page 440: ...74 4 9424200996 Virtual Control Switches 43 Test BE1 11m...
Page 450: ...75 10 9424200996 Logic Timers 62 Test BE1 11m...
Page 464: ...79 8 9424200996 Troubleshooting BE1 11m...
Page 480: ...80 16 9424200996 Specifications BE1 11m...
Page 600: ...84 56 9424200996 Settings Calculation Examples BE1 11m Figure 84 70 Logic Page 4 Part 1...
Page 602: ...84 58 9424200996 Settings Calculation Examples BE1 11m...
Page 608: ...85 6 9424200996 BESTCOMSPlus Settings Loader Tool BE1 11m...
Page 609: ......