Electrical PreDesign, SBU Rally - 2010Presented by,
Anoop Tiwari
Solutions
2. Directional earth fault protection devices for outgoing feeder
3. Earthing transformer
Power Plant Systems, Singapore
* | Presentation title, *
* | Presentation title, *
* | Presentation title, *
Power Factory Example- Line to Ground Fault Result in Ungrounded System
* | Presentation title, *
Transient overvoltage Problem
Earthing Transformer
* | Presentation title, *
* | Presentation title, *
* | Presentation title, *
Earth Fault protection Requirement For Unearthed Networks
S No.
Residual overvoltage protection (ANSI code 59 N)
This protection used to detect phase to earth and carried out via a voltage transformer with three windings whose tertiary is connected in an open delta.
7SJ62,7SN60,7SG13,REU610, 7SK80,REG670,7RW80
This protection function used to protect ungrounded system for line to ground fault.
If this protection function trips, it will result in tripping of all the other outgoing feeders which are connected to the collector bus.
2
Sensitive directional earth fault protection devices for outgoing feeder
To avoid spurious tripping, the outgoing feeders must be fitted with directional earth fault protection
7SJ62,7SN60,7SG13,REF543 7SK80,REG670,7SJ63,7SJ80, REF541,REX521
directional earth fault protection allows the capacitive current of a healthy feeder to be distinguished from the capacitive current of a faulty feeder Directional earth protection provide coordination with upstream protection.
In ungrounded system ground fault current is very small, for providing protection to such small current, we create a more sensitive system and this results in false tripping, seldom.
3
Earthing Transformer
It is used to provide a ground path on either an ungrounded Wye or a Delta connected system.
The fault current in the event of a grounded phase may be limited by the insertion of a grounding resistor with either a zig-zag scheme or a wye delta scheme
This solution is expensive.  
Power Plant Systems, Singapore
Copyright Notice
The documents are created by Vestas Wind Systems A/S and contain copyrighted material, trademarks, and other proprietary information. All rights reserved. No part of the documents may be reproduced or copied in any form or by any means—such as graphic, electronic, or mechanical, including photocopying, taping, or information storage and retrieval systems without the prior written permission of Vestas Wind Systems A/S. The use of these documents by you, or anyone else authorized by you, is prohibited unless specifically permitted by Vestas Wind Systems A/S. You may not alter or remove any trademark, copyright or other notice from the documents. The documents are provided “as is” and Vestas Wind Systems A/S shall not have any responsibility or liability whatsoever for the results of use of the documents by you.
Power Plant Systems, Singapore