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<< Click to Display Table of Contents >> Earth fault calculation considering conductor capacitances |
A a special report for calculations regarding earth fault management in impedance earthed medium voltage networks is available.
This type of calculation is optional and is conducted after selecting Extended earth fault analysis in the Advanced settings tab of the network calculation start form.
A simple text report and can be found as an extra report when right-clicking on a calculation in the Results/Administration form.
Description of calculation method and earth fault report.
Fault locations and printout points are limited to the following places.
Fault locations for earth faults will be calculated for every:
•Secondary side busbar in the primary sub station for 0 Ohm impedance, and for high Ohm (normally 3000 Ohm unless other value has been set)
•End point in radial. The node point located far out in each radial / feeder (lowest earth-fault current) for 0 Ohm, and for high Ohm
•Every node point that has a given reference earth point value.
Printout of earth fault values will be done for:
•The node point that is far out in every radial / feeder (lowest earth-fault current)
•The secondary side busbar in the primary sub-station
•The first section in every outgoing radial/ feeder
•The node point for every neutral point reactor located in the network outside of a primary substation.
•The system neutral point
Example Fault location.
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Fault position :SST005/ Resistance (ohm) :0.0
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Zero sequence current (A/dgr) 9320.9 / -31.4
Positive sequence current (A/dgr) 9320.9 / -31.4
Negative sequence current (A/dgr) 9320.9 / -31.4
Phase-A current (A/dgr) 27962.6 / -31.4
Phase-B current (A/dgr) 0.0 / 0.0
Phase-C current (A/dgr) 0.0 / 0.0
Zero sequence voltage (kV/dgr) 5.8 / 156.5
Positive sequence voltage (kV/dgr) 6.1 / -10.9
Negative sequence voltage (kV/dgr) 1.3 / -120.0
Phase-A voltage (kV/dgr) 0.0 / 0.0
Phase-B voltage (kV/dgr) 8.3 / -164.0
Phase-C voltage (kV/dgr) 8.3 / -164.0
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For every fault location the following is written:
Example Bus bar
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Print-out node Bus bar : DST01/
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Zero sequence voltage (kV/dgr) 0.7 / -176.2
Positive sequence voltage (kV/dgr) 6.7 / 0.0
Negative sequence voltage (kV/dgr) 0.0 / 0.0
Phase-A voltage (kV/dgr) 0.7 / -0.4
Phase-B voltage (kV/dgr) 6.7 / -124.7
Phase-C voltage (kV/dgr) 0.0 / 125.2
Input zero sequence current (A/dgr) 0.8 / 143.8
Input positive sequence current (A/dgr) 0.0 / 0.0
Input negative sequence current (A/dgr) 0.0 / 0.0
Input phase-A current (A/dgr) 0.8 / 143.8
Input phase-B current (A/dgr) 0.8 / 143.8
Input phase-C current (A/dgr) 0.8 / 143.7
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Example First section
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Print-out section (First line) :DST01/<->DST01/02
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Zero sequence current (A/dgr) 3.2 / -103.8
Positive sequence current (A/dgr) 2579.0 / 122.7
Negative sequence current (A/dgr) 2579.0 / 122.7
Phase-A current (A/dgr) 5155.7 / 122.7
Phase-B current (A/dgr) 2581.2 / -57.4
Phase-C current (A/dgr) 2581.2 / -57.4
Example Outer point
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Print-out node Outer node : DST01/02
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Zero sequence voltage (kV/dgr) 6.5 / 169.2
Positive sequence voltage (kV/dgr) 6.5 / -5.3
Negative sequence voltage (kV/dgr) 0.6 / -105.1
Phase-A voltage (kV/dgr) 6.5 / 0.0
Phase-B voltage (kV/dgr) 6.5 / -157.4
Phase-C voltage (kV/dgr) 0.6 / 141.4
Example Neutral neutral point reactor located outside of primary substations
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Printed point Local compensation : SST002/
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Zero sequence voltage (kV/deg) 6.7 / 180.0
Positive sequence voltage (kV/deg) 6.7 / -0.0
Negative sequence voltage (kV/deg) 0.0 / 0.0
Phase-A voltage (kV/deg) 6.7 / 0.0
Phase-B voltage (kV/deg) 6.7 / -150.0
Phase-C voltage (kV/deg) 0.0 / 150.0
Zero sequence current (A/deg) 1.4 / 90.0
Positive sequence current (A/deg) 0.0 / 0.0
Negative sequence current (A/deg) 0.0 / 0.0
Phase-A current (A/deg) 1.4 / 90.0
Phase-B current (A/deg) 1.4 / 90.0
Phase-C current (A/deg) 1.4 / 90.0
Current through reactor (3I0) (A/deg) 5.8 / 90.0
Current through capacitor (3I0)(A/deg) 1.4 / -90.0
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System Neutral Point
For every system neutral-point, the following is printed:
Node-point ID, zero sequence voltage, Currents
I0 Trf-Neutral point = Current per phase from transformer busbar through transformer and to neutral point
3*I0 Resist = Current through resistor
3*I0 React = Current through reactor
3*I0 Capac = Current through capacitor that represents other measured capacitive current
Example System Neutral Point.
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System neutral point Neutral point : DST01/
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Zero sequence voltage (kV/dgr) 6.7 / -180.0
Phase current trf-busbar (I0) (A/dgr) 7.5 / 140.0
Current through resistor (3I0 (A/dgr) 17.3 / -180.0
Current through reactor (3I0 (A/dgr) 17.3 / 90.0
Current through capacitor (3I0 (A/dgr) 2.8 / -90.0
Current Directions
References for positive current-directions
Fault location: Out from the network into the fault location
Printout point's busbar: Out from the busbar and towards the feeding-point (through the transformer)
Printout point's system neutral point and local reactors: Towards earthing
Printout section: Out from the busbar and towards the first point on the radial/ feeder