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Basis of Stator-GroundFault Protection The year of Profitable Growth
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Power Transmission and Distribution
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Generator Protection Basis of Stator-Ground-Fault Protection Presenter: Dr. Hans-Joachim Herrmann PTD PA13 Phone +49 911 433 8266 E-Mail:
[email protected]
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Test Results showing Effects of Arc Burning on Stator Core Laminations during Ground Faults Power Automation Progress. It‘s that simple.
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Power Transmission and Distribution
Methods of Neutral-Point Connection (1) Power Automation Progress. It‘s that simple.
? Isolated or high ohmic grounded
Advantage: Disadvantage:
Small fault currents High transient overvoltage at intermittent ground faults (2.5 – 3.5 ) Vph-E
< 10 A
Standard application ? Compensated or reactive grounded
Advantage: Disadvantage:
Small fault currents on the fault location Transient overvoltage (, 3I0> ? Direction (? 3V0, 3I0)
3V0
Ohmic current boost
IR
3I0
VL1
VL2
ICL2 IC ICL1
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Power Transmission and Distribution
Fault Currents in Case of a Direct Connection Power Automation Progress. It‘s that simple.
G1
IMess
G2
IMess
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Power Transmission and Distribution
Fault Currents in Case of a Direct Connection with Grounding Transformer Power Automation Progress. It‘s that simple.
G1
IMeas
Grounding transformer
G2
Ohmic current RB
IMeas
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Power Transmission and Distribution
Ground Current Detection via a Toroidal Current Transformer and Holmgreen Connection Power Automation Progress. It‘s that simple.
Toroidal Current Transformer IE 3
per phase
? magnetic addition of ground currents, ? principle is sensitive
I´E
Holmgreen connection (separate cores) IE 3
Holmgreen connection (common neutral return connector
L1 L2 L3
IE
per phase L1 L2 L3
I´E
(IE = 3 I0)
3~
?I
Sensitivity is limited Problem: Large CT ratio leads to small currents on the secondary side
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Power Transmission and Distribution
Directional Stator Ground Fault Protection Directional Characteristic Power Automation Progress. It‘s that simple.
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Power Transmission and Distribution
Directional Stator Ground Fault Protection - Logic Power Automation Progress. It‘s that simple.
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