Earthing Transformer Size for 5MVA 11KV Transformer | DPV

[DINAKAR P V]

dear all,

can you please suggest the size of the earthing transformer i should be using on HV for a 5MVA, 11KV Trasformer??

thnx
DPV

 

[sophiecentaur]

If you don't know how to find the answer to this sort of question, I should advise you to find (and Pay!) a consultant who can tell you. This is far too serious for 'idle chit-chat' on a forum like this - despite the high calibre of many of the contributors. I doubt that you can find anyone willing to chance his arm on this sort of health and safety question on the basis of so little information.
Sorry.

 

[dlgoff]

I thought I would give other readers of this thread some considerations when designing grounding systems, so I found this course on the subject.

http://www.pe.gatech.edu/courses/integrated-grounding-system-design-and-testing"

Here's what it covers:

Grounding System Design Principles

* Basic Concepts
* Accidental Electrocution Circuit Parameters
* IEEE Std. 80-2000 Edition
* IEC-479-1
* Lightning and EMC

Grounding System Performance

* Ground Potential Rise
* Fault Current Distribution
* Transferred Voltages
* Touch and Step Voltages
* Influenced on Comm/Control Circuits
* Influence on Piplines
* Analysis Methods

IEEE Std. 80 Design Procedure

* Conductor and Joint Selection
* Recommended Design Procedures
* Special Points of Danger
* Comparison of IEEE Std. 80 and IEC-479-1

Soil Characterization

* Soil Structures
* MEasurement Techniques
* Soil Samples
* Wenner Method
* Three-Pin Method
* Theory and Limitations
* Measurement Interpretation
* Computer Workshop

System Modeling for Grounding Design

* General Principles
* Modeling Requirements for GPR
* Design Options for GPR Reduction
* Modeling Requirements for Shielding Analysis
* Computer Workshop

Ground Mat Design for Safety

* Touch/Mesh/Step Voltages
* Metal-to-metal Touch Voltages
* Design Options for Touch Voltage Control
* Safety Assessment
* Computer Workshop

Integrated Grounding System Design

* Cost/Benefit Analysis
* Integreated Design Evaluation
* Transfer Voltages (pipelines, buildings, etc.
* Control Cable Shielding and Grounding
* Wind Farm Grounding
* Design Optimization
* Computer Workshop

Substation Lightning Shielding

* Basic Principles
* Shielding Angle
* The EGM Method
* Risk Assessment
* Design Procedures
* Workshop

Ground Design for Lightning

* Ground Surge Impedance
* Lightning Overvoltages and Propagation
* Transfered Voltage to Control Circuits
* Wind Turbine Protection
* Mitigation Methods

Ground Impedance Measurements

* Fall of Potential Method
* Theory and Limitations
* Factors Affecting Test Accuracy

Grounding System Testing and Evaluation

* Ground Impedance Measurements
* Ground Mat Measurements
* Tower Ground Resistance Mesurements
* Point-to-Point Ground Impedance Measurements
* Ground Integrity Test
* Touch and Step Voltage Measurements
* Transfer Voltage Measurements
* Probe Calibration
* Measurement Confidence Level
* Grounding Audit

 

[sophiecentaur]

Not a one word answer then!

 

[Bob S]

Here is a grounding solution I advise you not to use. I worked at a facility where the ac transformer for providing the 120V ac 60 Hz to my building had a delta secondary. So the engineers chose one of the three delta terminals as building ground. I worked there a year before I discovered the the standard 120 V outlet on my workbench was actually 120V 3 phase. (The facility was a well known university near Boston whose initials included T, I, and M.)

Bob S