Purpose of Neutral Grounding:-
Neutral of a3 Phase Star Connected Transformer is to be Earthed Properly to Enable Earth-Fault protection for STATOR Windings & associated Systems & also to Limit Transient Over-voltage during Fault in System or Switching, Lightning, or Heavy Load through-off or long time Unclear fault in the System etc.etc.
In such Faults it limits the Earth fault current to less than Full load Current , for a terminal Earth Fault.
It gives System stability, by providing easy path for Unbalance system Current/Voltage into the ground during fault Condition, thus System got Stabilized..
These are process of Grounding the Neutral :-
1. Connect Neutral with Ground / Solid Earthing ( Small Distribution trafo)
2.Resistance Grounding : - Connect Neutral with Ground through Metal-Grid type Resistor. For Large or Medium Voltage Transformer.Resistors are short time tated for30 seconds.
3.High Impedance Grounding:- Neutral is Earthed through Primary winding of a distribution Transformer & A loading Resistor is connected across low voltage secondary.
4. Ziz-zag- or Star/Delta transformer in the Tertiary Winding to Neutralise Earth fault current into the Ground.
Necessary Relaying against different faults in System When System Neutral is Grounded:-
1) Connect CT in the Neutral of Proper Rating ( Say100/1, 25/1 according System design). Standby-Earth fault Protection, gives100% protection against Earth-Fault.
2) Connect3 PT in Open-Delta , PT Open_Delta is the Sensing of Neutral displacement Relay.
VDG-14. In normal condition Open-Delta point Voltage will be Zero, but in case of Fault There must be some voltage in Open-Delta-point. Typical setting5-20 Volts.
3) Instantaneous Earth Fault Relay.
Chemical earthing Supplier in Noida
Keywords
easy path
short time
Heavy Load
Connect CT
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load Current
Proper Rating
PT Open Delta
Solid Earthing
Connect Neutral
STATOR Windings
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Tertiary Winding
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loading Resistor
Neutral Grounding
associated Systems
time Unclear fault
terminal Earth Fault
Star Delta transformer
Neutralise Earth fault
Open Delta point Voltage
distribution Transformer
Metal Grid type Resistor
Small Distribution trafo
Typical setting5 20 Volts
Instantaneous Earth Fault
Neutral displacement Relay
3 High Impedance Grounding
Star Connected Transformer
Chemical earthing Supplier
Limit Transient Over voltage
Enable Earth Fault protection
Standby Earth fault Protection
Unbalance system Current Voltage
Medium Voltage Transformer Resistors
