types of faults in transformer and each problem how to solve it and which type of...

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Electrical Engineering

types of faults in transformer
and each problem how to solve it and which type of test foreach problem online or offline

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External Faults in Power Transformer External Short Circuit of Power TransformerThe short circuit may occur in two or three phases ofelectrical power system The level of fault current is always highenough It depends upon the voltage which has been shortcircuitedand upon the impedance of the circuit up to the fault point Thecopper loss of the fault feeding transformer is abruptly increasedThis increasing copper loss causes internal heating in thetransformer Large fault current also produces severe mechanicalstresses in the transformer The maximum mechanical stresses occurduring first cycle of symmetrical fault currentHigh Voltage Disturbance in Power TransformerHigh voltage disturbance in power transformerare of two kindsTransient Surge VoltagePower Frequency Over VoltageTransient Surge VoltageHigh voltage and high frequency surge may arise in the powersystem due to any of the following causesArcing ground if neutral point is isolatedSwitching operation of different electrical equipmentAtmospheric Lightening ImpulseWhatever may be the causes of surge voltage it is after all atraveling wave having high and steep wave form and also having highfrequency This wave travels in the electrical power systemnetwork upon reaching in the power transformer it causesbreakdown of the insulation between turns adjacent to lineterminal which may create short circuit between turnsPower Frequency Over VoltageThere may be always a chance of system over voltage due tosudden disconnection of large load Although the amplitude of thisvoltage is higher than its normal level but frequency is same as itwas in normal condition Over voltage in the system causes anincrease in stress on the insulation of transformer As we knowthat voltageincreased voltage causes proportionate increase in the workingfluxThis therefore causes increased in iron loss and proportionatelylarge increase in magnetizing current The increase flux isdiverted from the transformer core to other steel structural partsof the transformer Core bolts which normally carry little fluxmay be subjected to a large component of flux diverted fromsaturated region of the core alongside Under such condition thebolt may be rapidly heated up and destroys their own insulation aswell as winding insulationUnder Frequency Effect in Power TransformerAs voltageasthe number of turns in the winding is fixedThereforeFrom this equation it is clear that if frequency reduces in asystem the flux in the core increases the effect are more or See Answer

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