Let me share my school knowledge with you.
A protection marge as 1.15 is selected. This is the ratio of a voltage level and the protection voltage level.
The voltage level is the strength level of the protected device.
The protection level is:
V2 = Va (arrester voltage) + Vb (connection...
Hi Tarek, I worked on a commissioning of a SEL 300G relay. You can download its manuel and find reasonable knowledge over protection of generators...
http://www.selinc.com/sel-300g.htm
Do you mean the codes related to generator protection?
These can help you:
25 : synchronism check
40 : under excitation
55 : power factor correction
66 : motor start
87 : differential
-Said-