"SLC22/WK1: Advanced Electrical Transformers and the Power Factor."

Source

If I talk about names of transformer that are shown by diagram are below;

A : Step up transformer.
B : Step down transformer.

Reasons

If I talk about A which I called as Step up transformer then it is used for conversion of low voltage to high voltage for more transmission so we can see clearly in first diagram which is A that voltage conversion is from low to high which is 220V to 415V so here transformer is step up.

If I talk about B which I called as step down transformer then it is used aur conversion of high voltage to low voltage and hence final consumption occur in this way so you can clearly see in diagram that there is conversion starting from high voltage to low voltage which is from 415 voltage to 220 voltage.That's why I can say that this is step down transformer.

A :Conservator

If I talk about conservator then this is part of power transformer which is useful for storage of oil and this part is helpful in expanding and contracting with alternation in temperature.

B:Temperature gauge

If I talk about temperature gauge then this is again a part of power transformer which is used for analysing winding temperature ,oil and ambient air so that if there is overheating then it may get detected.

C :Buchholz Relay

If I talk about Buchholz relay then this is a part of power transformer which is just like a device which is useful for carrying out fault detection like if there will be any problem in form of oil leaking and overheating etc then this device will be useful for detecting it and after detection of any problem and alarm will trigger automatically.

D:Radiator

If I talk about another part of power transformer then this is radiator which main purpose is driving out heat which is generated by transformer and for increasing surface area fins and tubes can be used in it.

E:LT Bushing

If I talk about low tension bushing then this is not primary side of power transformer,it's secondary side but it is useful for insulation and connection of low voltage winding to output circuit.

F:HT Bushing

If I talk about High tension bushing then this is primary side of transformer which is useful for insulation, connection and high voltage inputting to high voltage winding of transformer's input circuit.

G:Breather

If I talk about another part of power transformer then this is breather which is useful for permitting entry and exit of air in and out but moisture will remain and it will be done by preventing of oil degradation.

If I talk about type of transformer which is used for my home electricity then this is step down transformer which is typically mounted at poles and it serves as a particular area like neighbourhood or small community.

If I talk about primary coil of transformer then these are connected with powerhouse that supplies 11000 volts of electricity. This is a high voltage which is significant for efficient transmission of electricity to longer distances.

If I talk about secondary calls of transformer then these are connected with homes schools colleges and offices in area. If I talk about the way in which this transformer is stepping down from high voltage to low voltage then it step down from 11000 volt to 220 volts that is safest for household usage.

If I conclude then step down transformer is useful for reduction of high voltage of electricity which is transmitted from powerhouse to low voltage is most safe for using in household and in some businesses and this process is really significant for giving surety of safest and efficient electricity distribution two homes and businesses.

If I talk about calculation of required transformer size in KVA there's need of considering power factor of the load.So if I talk about power factor then this is ratio of the real power (in kW) to the apparent power (in kVA).

If we suppose that a typical power factor of 0.8 for a commercial or industrial load then we may calculate desired transformer size in following way;

Apparent Power (kVA) = Real Power (kW) / Power Factor (PF)
= 5000 kW / 0.8
= 6250 kVA

Now, 6250 kVA transformer may be actually needed for supporting a 5000 kW load by supposing a power factor of 0.8.

Transformer Name: Energypac
Transformer Rating = 2500 KVA
Primary Voltage(HV) = 33000 KV
Secondary Voltage (LV) = 415V
Current(HV) = 43.74 Amp
Current(LV) = 3478.11 Amp

If we have to find out currents in high voltage (HV) and low voltage (LV) sides of the transformer then it's important to use these formulas:

HV Side Current (I_HV) = Transformer Rating in MVA divided by √3 × HV Voltage in kV

= 2.5 MVA / (√3 × 33 kV)
= 2.5 MVA / (1.732 × 33 kV)
= 43.79 A

LV Side Current (I_LV) = Transformer rating in MVA divided by √3 × LV Voltage in kV

= 2.5 MVA / (√3 × 0.415 kV)
= 2.5 MVA / (1.732 × 0.415 kV)
= 3465.22 A

Now after calculation it is clear that currents in the high voltage and low voltage sides of the transformer are below;

HV Side Current (I_HV) = 43.79 A
LV Side Current (I_LV) = 3465.22 A

If I talk about power factor is ratio of actual power which is active power to apparent power in electrical power system. It's basically measurement that how much efficiently current is drawn from grid which is converted in useful work. Power factor is represented as value between 0 and 1.

Power factor = Real Power in kW divided by Apparent Power in kVA

If I talk about Pakistan then power factor value that is highly recommended by electricity supply companies is most probably lies in between 0.85 and 0.95.But, there are some of electricity supply companies that have some particular needs recommendations for power factor.

As an example of I talk about city Karachi Electric Supply Company (KESC) then their recommendations are a power factor of 0.9 or higher for consumers of industrial and commercial level.On other hand in city Islamabad Electric Supply Company is recommending a power factor of 0.85 or more than this for all consumers.

It's most important to note that a low power factor may result in punishment and additional charges from electricity supply company because it may be a cause of less efficient usage of electrical grid.

These are three major and other differences;

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