Handbook of Electrical Engineering

390 HANDBOOK OF ELECTRICAL ENGINEERING Figure 14.2 Variable applied voltage with a high resistance rotor design for an induction ...

VARIABLE SPEED ELECTRICAL DRIVERS 391 complicated winding reconnections can be devised to produce more than just two speeds from ...

392 HANDBOOK OF ELECTRICAL ENGINEERING power electronic controllers are available for even the largest motors, the use of wound ...

VARIABLE SPEED ELECTRICAL DRIVERS 393 Figure 14.3 Schematic diagram of a variable voltage and variable frequency rectifier inver ...

394 HANDBOOK OF ELECTRICAL ENGINEERING torque-slip characteristic for operation at various supply frequencies. This method, and ...

VARIABLE SPEED ELECTRICAL DRIVERS 395 when properly selected, operated and maintained, provide an acceptably economic means of l ...

396 HANDBOOK OF ELECTRICAL ENGINEERING 14.5.2.2 The seal or protector The seal (or protector) operates, as its name implies, to ...

VARIABLE SPEED ELECTRICAL DRIVERS 397 14.6 Control Systems for AC Motors In the oil industry the use of variable speed AC motors ...

398 HANDBOOK OF ELECTRICAL ENGINEERING Figure 14.5 Block diagram of the control system for an induction motor fed from a variabl ...

VARIABLE SPEED ELECTRICAL DRIVERS 399 The control of motor speed essentially requires two components, one for varying the termin ...

400 HANDBOOK OF ELECTRICAL ENGINEERING ability of the model to store the non-linear parameters of the motor e.g. stator and roto ...

15 Harmonic Voltages and Currents 15.1 Introduction It is generally understood that the voltages and currents in industrial powe ...

402 HANDBOOK OF ELECTRICAL ENGINEERING The use of rectifiers and inverters for variable speed motor drives is becoming common in ...

HARMONIC VOLTAGES AND CURRENTS 403 Figure 15.1 Circuit diagram of a six-pulse thyristor bridge. Figure 15.2 Voltage and current ...

404 HANDBOOK OF ELECTRICAL ENGINEERING A time delay is incurred until the zero is reached, and the corresponding angle is ‘α’ wh ...

HARMONIC VOLTAGES AND CURRENTS 405 ‘gate’. It cannot be turned ‘off’ by the control signal. It can only be turned ‘off’ by forci ...

406 HANDBOOK OF ELECTRICAL ENGINEERING Table 15.2. Variation of harmonic coefficients with the commutation angleu Harmonic numbe ...

HARMONIC VOLTAGES AND CURRENTS 407 The spacing need not be greater than about 1000 mm unless the parallel route length is very l ...

408 HANDBOOK OF ELECTRICAL ENGINEERING An alternative expression forVdin terms of the commutation angleu,is, Vd= 3 √ 6 E 2 π (co ...

HARMONIC VOLTAGES AND CURRENTS 409 The power factor of the fundamental phase current in the reference phase of the secondary win ...