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Design And Application Of Power Transformers

Power transformers Manufacturers India changes the magnitude of voltage and current in a power system. Faraday’s induction principle and the fluctuation in ampere-turns generate this transition (or winding turns). Keep in mind that the amount of electricity delivered remains the same (minus a few core and copper losses).

Design of a Power Transformers 

Six major components make up a Power transformers Manufacturers India. Understanding component design as a power engineer allows you to specify transformers accurately.

What makes a shell-type transformer superior to a core-type Power Transformer?

Although more expensive to manufacture (due to additional material), the shell-type transformer is superior to the core-type transformer for the following reasons.

Has a high short-circuit current withstand rating. When the windings flex or twist during short-circuit, the laminated metal sheets around them act bracing.

The limbs on the outside give an additional way for the leakage flux to flow. Local overheating happens without this escape route, as it does in core-type.

The interleaved disc windings can withstand a voltage surge better.

Winding design

What goes into the design of transformer windings?

The current is goes via the windings. As a result, increasing the turns around the core increases the voltage induced, while decreasing the turns decreases the voltage generated.

Using a continuously transposed conductor (CTC) for primary and secondary windings ensures exceptional mechanical stability (because magnetic fields cancel). The flat copper conductor is use for tertiary or stabilizing windings.

What is the benefit of interlacing the Power Transformers windings?

Mini-capacitors are create by interleaving the turns, which help break down the incoming voltage spike and bury it in the windings. Placing a shield wire (flat copper) between the twists is another approach to channel the surge.

Bushing design

What is the purpose of a Power Transformers bushing?

Bushings let electricity flow from the energized (high voltage) conductor to the inside of the tank’s windings (without energizing the tank). Two places of contact should be on your mind—one, where the conductor lands at the top.

The porcelain insulator maintains the phase-to-ground clearance.  The capacitance or condenser bushing is the name for this sort of bushing.

This is characteristic of transformers operating at high voltages (HV, EHV, and UHV). Resin (dry) bushings can be use at medium voltages and below.

Design of a load tap changer

What is an On-Load Tap Changer use for?

The voltage at the substation either falls or increases as the load grows or decreases. The number of winding spins can be increase or decrease to maintain the voltage steady (remember, adding secondary turns increases voltage or vice-versa).

Design of a tank

Tank design is where you get creative to support site and project needs. Bushings can be specified on any side;

Another important design issue is whether to use three 1-phase transformers or just one 3-phase transformer. Large power plants’ generator step-up transformers, as well as transformers in EHV substations, are three-phase.

Even if one bank is out of service, a single 3-phase transformer will not operate, whether core or shell.

This 3-phase transformer, on the other hand, is less expensive to produce, has a smaller footprint, and performs at a better efficiency.

Design of the cooling system

How does the heat in the tank get distribute?

Heat is generated by the current flow in a copper coil. This heat is extracted by mineral oil. The natural convection movement of oil normally dissipates heat: Hot oil rises to the top, then goes to radiators, then cools, settles, and returns to the main tank, where it heats up and rises again (process repeats).

Connect a bank of fans to the radiators or heat exchangers to improve cooling. Pumps can be used to force oil movement (via the tank or the windings) to enhance things even more.

The effects of Transformer Grounding on Power System Design. 

Without much detail, the star connection is the chosen high voltage transmission connection for cost savings and safety. The neutral — the common point – is grounded or earthed in this circumstance.

The phase to neutral or phase to earth voltage is lowered by 1/sqrt when this is done (3). With a delta (ungrounded) connection, you won’t obtain this reduction.

Only a delta-star Power transformers Manufacturers India near the generating station, with the delta linked to the generator terminals and the star connected to the high voltage transmission lines, makes sense.

The transformer winding can be insulate for lower (phase-to-ground) voltages by using a ground star connection on the high voltage side. The transmission system insulation requirements will be reduced as well. These allow for significant cost reductions in the transmission system’s design and construction.

However, grounding the transformer neutral has a drawback. The grounded neutral of the transformer acts as a return path for the fault current when one or all three lines on the star side short-circuit to the ground.

Third harmonic currents are abundant in ground fault currents. The transmission line’s third harmonics impair all nearby communication channels (for example, power line carrier – pilot relaying).

However, all is not loss with the star-delta/delta-star combo (because of neutral grounding). The delta connection has a high impedance for third harmonics and traps the ground-fault current, preventing it from spreading from one side to the other.

Conclusion

In generating stations and load centers, delta-star Power transformers Manufacturers India applied in transmission substations that is star-delta transformers (765kV, 500kV, 345kV).

Although grounding the neutral results in higher ground fault currents, neutral grounding is acceptable due to the cost savings gained from lower insulation needs.

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