Question { 23959 }

why transmission voltages are in multiple of 11kv?

Answer

IT is due to the form factor which equal to 1.111111.
therefore the transmission voltages are in multiple of 11.

Question { 5800 }

What's an AVR? What's its purpose in Generators?

Answer

AVR-Automatic voltage regulators. alos they are called line
drop compensators. they are used to regulate the supply
voltage to the distribution network. thay r used in
transformers and generators. they sense the secondary PT
voltage and correspondingly change the tap position of OLTC
to regulate the secondary output voltage.

Question { 11504 }

1)Why potential transformer primary site grounded?
2)can be loop between neutral & body for grounding?
3)What is the difference between ELCB &RCCB?
4)Why we use iron core in transformer insted of wooden core?
5)what is the principle of excitation?
6)Why we test the core balance test for transformer?
7)what is creepage?What is the creepage length for
insulators at different voltages?
8)How much type of relays used for differential protection
of generator,transformer & busbar protection?

Answer

1. Here the HV or LV of THE TRANSFORMER is not concerned.
The star side of the transformer is grounded. i.e the
neutral of the star side is grounded for detecting the
earth fault current in case of earth fault in the protected
zone of the transformer.

2. No the body and the neutral should be grounded
separately . because huge fault current can flow in the
body and other auxilliary protection in case of a earth
fault.

8. Differential protection relays are used. eg ABB
SPAD346C1,c2,c3, Siemens 7ut612 etc .