What are the malfunctions and abnormal operation of the transformer? What is the difference between them and the line?
working principle:
Transformer is the use of electromagnetic induction principle made of static appliances. When the transformer's original coil connected to the AC power supply, the core will produce alternating magnetic flux, alternating magnetic flux with φ said. The original, the secondary coil φ is the same, φ is also a simple harmonic function, the table for the φ = φmsinωt. By Faraday's law of electromagnetic induction, we can see that the induced electromotive force in the original and secondary coils is e1 = -N1dφ / dt, e2 = -N2dφ / dt. Where N1, N2 is the original, the number of turns of the secondary coil. U1 = j1n1, U2 = E2 = -jN2ωΦ, and the complex value is U1 = -I1 = jN1ωΦ, U2 = E2 = -jN2ωΦ, and the complex value is U1 = Let k = N1 / N2, said the variable ratio of the transformer. U1 / U2 = -N1 / N2 = -k, that is, the ratio of the original value of the transformer and the secondary coil voltage, is equal to its turns ratio and the difference between the original and the secondary coil voltage is π.
And then come to:
U1 / U2 = N1 / N2
In the case of no-load current, I1 / I2 = -N2 / N1, that is, the original and secondary coil current RMS value is inversely proportional to the number of turns, and the phase difference π.
And then available
I1 / I2 = N2 / N1
Ideal transformer original, vice coil power equal P1 = P2. Indicating that the ideal transformer itself without power loss. The actual transformer always has the loss, its efficiency is η = P2 / P1. Power transformers are highly efficient and up to 90%.
Transformer failure: can be divided into the tank failure and tank failure. Fuel tank failure: a short circuit between the windings, short-circuit between the turns, direct grounding system side winding short circuit. Outside the tank failure: There is a short circuit between the casing and the lead wire and the ground short circuit (direct grounding system side). Transformer is not working properly: there are external faults caused by over-current, overload, oil level and due to over-voltage or frequency caused by over-excitation and so on. Line fault: phase short circuit (including three-phase short circuit, two-phase short circuit), two-phase ground short circuit, single-phase ground short circuit, transmission line disconnection.
