Relationship between System Earthing & circuit protection
Relationship between System Earthing & circuit protection
(OP)
Is there any particular relationship between the type of system earthing and the protection of the circuit?
What are the typical examples.
Regards,
Mithko
What are the typical examples.
Regards,
Mithko






RE: Relationship between System Earthing & circuit protection
Draw a simple circuit yourself and study.
Rafiq Bulsara
http://www.srengineersct.com
RE: Relationship between System Earthing & circuit protection
In addition, different earthing schemes (resistance, zig-zag transformer, etc.) will affect the magnitude of the ground fault current. This must be taken into account when designing protection systems and selecting settings.
RE: Relationship between System Earthing & circuit protection
RE: Relationship between System Earthing & circuit protection
With all due respect, your above statement is incorrect. In two winding transformers, secondary current will not return to primary winding. The current will only "return" to its source winding. Ungrounded delta has no return ground path. (Not withstanding capacitive coupling for large systems or systems with very long cables. That is a separate discussion).
ZCT is not for detecting ground (or earth) faults in ungrounded delta systems. There are other means of detecting first GF in ungrounded systems.
You may want red flag your post and post a revised one if you wish.
Rafiq Bulsara
http://www.srengineersct.com
RE: Relationship between System Earthing & circuit protection
You state this is incorrect, but the priciple is applied currently by multiple manufacturers including Siemans and Schneider Electric, with three phase, three wire systems. And I assure you, they do work. If you wish, I can find one of their drawings for this system utilizing a zero-sequence CT. Though it might be early next week when I can post a file of it (I do not have it with me here in the field).
RE: Relationship between System Earthing & circuit protection