Question

What is active power in delta unbalanced circuit when phase current is 0?

Answer 1

I have a very basic question about three phase system. I am not an electrical engineer hence I might not have a good understanding of the subject. So, please be bit lenient in answering and asking clarifications.

My home receives a 220v (between one phase and neutral) 3 phase connection from grid. From the post comes 4 wires to our home. Each phase is connected to various loads in my house and since not all loads will be switched on, the three phase circuit will be unbalanced.

So, if I draw a very crude schematic diagram with text:

R--------L1---+
|
Y-----L2---+ |
| |
B---L3--+ | |
| | |
N-------+--+--+
R, Y, B are the three phases, N is the neutral and L1, L2 and L3 are the loads (unequal resistive and inductive combined).

What happens when the connection to neutral fails as shown by the following diagram?

R--------L1---+
|
Y-----L2---+ |
| |
B---L3--+ | |
| | |
N-- ---+--+--+
^
|
+------- Neutral disconnection
Some say that the loads L1, L2 and L3 experience high voltages as they will be connected between phases rather than between phase and neutral.

While some say that the entire circuit will self adjust and achieve a balance.

ohk ......i hope help you