transformer connections

[trackatino]

hi every body i'm new to transformers..can anybody send me pics on how to connect tranformers in the various connection types...like delta-y....

 

[davidbeach]

faq238-1287

 

[arnabanindita]

We are using zig-zag transformer for system earthing in 33 kV, 6.6 kV system in an Oil and Gas Industry. Zig-zag transformer is earthed via a resistor to limit the fault current to 200 A. Now, we want to increase fault current to 400 A. Proposal is to connect another zig-zag transformer. This will serve dual purpose of increasing fault current as well as redundancy in system earthing in case of failure of one zig-zag.
My question is - instead of connecting another, cannot we reduce the resistance to increase the fault current to 400 A (zig-zag is rated for 400 A)? If we remove resistance will there be difficulty in segregating faulter feeder from un-faulted one (due to smaller angle difference between faultd and un-faulted one)? If both zig-zag are in service, will there be any change of angle of faulted current from earlier case of one zig-zag due to paralleling of earth fault current?
Another question - can we use directional negative sequence over current protection along with directional earth fault protection to increase reliability in detecting faulted feeder in case of earth fault?

 

[VTer]

arnabanindita,

you should start a new thread for this question

"Throughout space there is energy. Is this energy static or kinetic! If static our hopes are in vain; if kinetic — and this we know it is, for certain — then it is a mere question of time when men will succeed in attaching their machinery to the very wheelwork of nature". – Nikola Tesla