## Equivalent circuit of a polyphase induction machine, Electrical Engineering

Assignment Help:

Equivalent Circuit of a Polyphase Induction Machine

The inductionmachinemay be regarded as a generalized transformer inwhich energy is converted and electric power is transferred between stator and rotor, along with a change of frequency and a flow of mechanical power. At standstill, however, the machine acts as a simple transformer with an air gap and a short-circuited secondary winding. The frequency of the rotor-induced emf is the same as the stator frequency at standstill. At any value of the slip under balanced steady-state operation, the rotor current reacts on the statorwinding at the stator frequency because the rotating magnetic fields caused by the stator and rotor are stationary with respect to each other. The induction machine may thus be viewed as a transformer with an air gap and variable resistance in the secondary; the stator of the induction machine corresponds to the transformer primary, and the rotor corresponds to the secondary. For analysis of the balanced steady state, it is sufficient to proceed on a per-phase basis with some phasor concepts; so we will now develop an equivalent circuit on a per-phase basis. Only machines with symmetrical polyphase windings excited by balanced polyphase voltages are considered. As in other discussions of polyphase devices, let us think of three-phase machines as wye-connected, so that currents are always line values and voltages are always line-to-neutral values (on a per-phase basis).

The resultant air-gap flux is produced by the combined mmfs of the stator and rotor currents. For the sake of conceptual and analytical convenience, the total flux is divided into a mutual flux (linking both the stator and the rotor) and leakage fluxes, represented by appropriate reactances.

#### Calculate efficiency to load at unity power factor, Q. A 300-kVA transforme...

Q. A 300-kVA transformer has a core loss of 1.5 kW and a full-load copper loss of 4.5 kW. (a) Calculate its efficiency corresponding to 25, 50, 75, 100, and 125% loads at unity

#### Show typical performance parameters for voltage regulators, Q. Show Typical...

Q. Show Typical performance parameters for voltage regulators ? Typical performance parameters for voltage regulators are · Line regualtion · Load regulation · Tempara

#### Explain the properties of low resistivity materials, Explain the properties...

Explain the properties of low resistivity materials. Low resistivity materials: The conducting materials containing resistivity from 10 -8 to 10 -6 ohm-m come under this cl

#### There are many advantages of plc - stepper motor , There are many advantage...

There are many advantages of PLC a.The PLC  was specifically designed for harsh  conditions with  electrical  noise magnetic fields vibration  extreme temperatures or humidit

#### State the nyquist sampling theorem, (a) Which one of the four digital-to-a...

(a) Which one of the four digital-to-analog conversion techniques (ASK, FSK, PSK or QAM) is most susceptible to noise? Explain your answer. (b) Given the bit pattern 01001110,

#### Digital electronics, design a 6 modulo ring counter

design a 6 modulo ring counter

#### Evaluate the travel time of signal, Suppose that the length of a 10Base-5 ...

Suppose that the length of a 10Base-5 cable is 2500 metres. If the speed of propagation in a thick co-axial cable is 60% of the speed of light, how long does it take for a bit to

#### Dc machines, a 400V 4-pole DC generator takes an armature current of 50A wh...

a 400V 4-pole DC generator takes an armature current of 50A when rotating at 626 rpm. the armature circuit resistance is 0,25ohms. determine the generated emf. DOC

#### Determine the laplace transform of the waveform, Q. Determine the Laplace t...

Q. Determine the Laplace transform of the waveform shown in Figure.

#### Clampers.., plz give ans about signs of capicitor, and give detail about cl...

plz give ans about signs of capicitor, and give detail about clampers.

### Write Your Message!  #### Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!