Question { Oracle, 395899 }

transformers parts & function of each parts

Answer

Transformer Parts and their Functions

• CONSERVATOR
Conservator is a cylindrical tank, situated at upper portion of power transformer and is connected to transformer tank through pipe. It provides adequate space for expansion of oil whenever transformer internal temperature rises or ambient temperature changes. It also facilitate for filling of oil in transformer’s tank.

• MAIN TANK
This part of transformer contains the assembly of core and both primary and secondary windings immersed in insulating oil.
• RADIATORS
These are tube like structures, connected with transformer tank and provides circulating path for transformer oil for cooling purpose.
• BUCHHOLZ RELAY
It is a very sensitive gas and oil operated instrument which is used to protect transformer windings, safely detect the formation of gas or sudden pressure inside the oil transformer. This is a double ended device one end is connected to conservator other is connected to tank. There are two float switches inside the relay one is connected to alarm circuit for warning and other is connected to trip circuit to protect transformer against damage.
• BREATHER
Breather is a device which contains a chemical material (Silica Gel) and is used for air take in/out of the sealed transformer
• SILICA JEL
Silica Gel Blue semi-transparent glassy substance containing an indicator as “Cobalt Chloride” a heavy metal salt. When free from moisture the Granules or beads are dark blue in color. As the beads takes up moisture, they turns to light blue gradually & finally turn to pink.
• OIL LEVEL SCALE
This part is situated on the side of conservator tank for verification of specific oil level at specific temperature.
• PRIMARY WINDING
Copper wound coils places of the limbs of core, used as primary winding (circuit) to transmit power to secondary winding via magnetic circuit. No of turns of coils depends upon the rating of transformer.
• TAP-CHANGER
A tap changer is a connection point selection mechanism mounted on transformer main tank at HT winding that allows a variable number of turns to be selected in various steps. A transformer with a variable turns ratio is produced, enabling stepped voltage regulation of the output. The tap selection may be made via an automatic or manual tap changer mechanism.
SECONDARY WINDING
Copper wound coils used as secondary winding (circuit) to transmit power to Loads. No of turns of coils depends upon the rating of transformer. Primary and secondary windings are electrically isolated from each other but magnetically coupled via iron core.
• IRON CORE
The primary and secondary windings are wrapped around a core (made by thin, soft laminated layers of steel). The purpose of the iron core is to provide low reluctance path to the magnetic flux generated by primary winding, to link with the secondary winding for induction.
• PRESSURE RELIEF PIPE or EXPLOSION VENT
To avoid Critical situation due to extreme pressure developed in transformer tank, a pipe is mounted on transformer tank called pressure relief pipe, containing bursting plate breaking device which burst to discharge the pressure and protect transformer.
• DRAIN VALVE
This valve is situated under the oil tank and is used for taking out transformer oil. (For purpose of dehydration and purification, transformer maintenance or replacing with new oil etc).
• HT/ BUSHINGS
Porcelain insulated device that allows the connection terminals of primary and secondary winding to pass safely through the (earthed conducting) tank for connection purpose. Bushings prevent unwanted leakage of electricity.

Question { 4007 }

what is the contact resistance of Air circuit breaker??

Answer

contact resistance should be always less than 35 micro ohm.

Question { L&T, 18187 }

What is the problem, if a circuit breaker is not closing.

Answer

if u provide me the drawing of the panel i shall guide u in step by step