Transformer Taps & OLTC

Dear Reddy,

All Transformers normally having OLTC on its Primary side to avoid high current and easy to control.

As you said, 13th Tap having three a,b & c , because it is the center pint of Taps, where you can precisely maintain the ideal voltage level.My understood is you have to keep the any one tap at a time, either of three. you have press three times to surpass the 13th tap.

for more details you need to contact manufacturer and refer manufacturer's manual.

bye

Dear Sir,

Thank you very much,

BVREDDY.

Hyderabad,

The OLTC is placed on the HIGH VOLTAGE side of the transformer to minimize the physical size ( resulting in smaller motor to operate or smaller forces to turn the crank handle manually) and cost of manufacturing since the current is lower on that side and copper contacts will be smaller.

At this level , we don't normally speak of primary and secondary especially as in your substation application where the transformer is coupling two high voltage transmission lines of different voltages. The power flow can be bi-directional hence there is technically no true primary and secondary.

The 13th tap is the midposition. I can't seem to figure of why they will have a 13A,13B and 13 C .

Dear BVREDDY,

I'll try to answer your questions as best as I can since I have some confusions with them.

OLTC is preferably/usually installed in the primary side. This is done to have a lower current in the diverter switch as it changes taps. The arcing will be lesser compared to an arcing with higher current. To put it directly, the OLTC will be costlier if it is designed to operate at higher currents.

For your second question, if your OLTC has three diverter switches, one for each phase, then you could say that three tap changes happens for every tap position number. 13A - diverter switch for tap position number 13 phase A, 13B - diverter for tap position number 13 phase B and 13C - diverter for tap position number 13 phase C.

Dear Sir,

Thank you...for reply.

Regards

BVREDDY

please see www.reinhausen.com this is the world biggest OLTC manufacturer.

Here you can download a lot of information:

www.reinhausen.com/en/desktopdefault.aspx/tabid-56/