viii ' CONTENTS
PAGE
giving high current and torque at resonance speed—Calcula-
tion of motor.....................16
12. Equations of motor'—Equation of torque—Speed range, of
maximum torque....................17
13. Numerical instance—Volt-ampere capacity of required con-
denser.........................IS
14. C. Multispeed motors—Fractional pitch winding, and switch-
ing of six groups of coils in each phase, at a change of the num-
ber of poles......................20
15. Discussion of the change of motor constants due to a change of
the number of poles, with series connection of all primary turns
—Magnetic density and inferior performance curves at lower
speeds.........................21
16. Change of constants for approximately constant maximum
torque at all speeds—Magnetic density and change of coil
connection......................22
17. Instance of 4 -f- 6 -5- 8 pole motor—Numerical calculation and
discussion....................... 23
CHAPTER II. MULTIPLE SQUIRREL CAGE INDUCTION MOTOR.
18. Superposition of torque curves of high resistance low reactance,
and low resistance high reactance squirrel cage to a torque
curve with two maxima, at high and at low speed......27
19. Theory of multiple squirrel cage based on the use of the true
induced voltage, corresponding to the resultant flux which
passes beyond the squirrel cage—Double squirrel cage induc-
tion motor......................28
20. Relations of voltages and currents in the double squirrel cage
induction motor....................29
21. Equations, and method of calculation...........30
22. Continued: torque and power equation..........31
23. Calculation of numerical instance of double squirrel cage
motor, speed and load curves—Triple squirrel cage induction
motor........................32
24. Equation between the voltages and currents in the triple
squirrel cage induction motor..............34
25. Calculation of voltages and currents...........35
26. Equation of torque and power of the three squirrel cages, and
their resultant . . . :........*......'. . 37
27. Calculation of numerical instance of triple squirrel cage induc-
tion motor—Speed and load curves............37
CHAPTER III. CONCATENATION.
Cascade or Tandem Control of Induction Motors
28. Synchronizing of concatenated couple at half synchronism—
The two speeds of a couple of equal motors and the three