Page 8 - Industrial Power Engineering and Applications Handbook

Contents

Prejkice ix 6 Static Controls and Braking of Motors
Ackiiowledgernents xi Speed control in squirrel cage motors . Speed control
...
Technical support Xlll through solid-state technology . Vu control (speed
Introduction xv control at constant torque) . Phasor (vector) control .
Use of phasor control for flux braking . Control and
feedback devices . Application of solid-state
Part I Selection, Testing, Controls technology ' Conduction and commutation . Circuit
and Protection of Electric Motors configurations of semiconductor devices . Smoothing
ripples in the d.c. link ' Providing a constant d.c.
voltage source 4 Providing a constant current source .
1 Theory, Performance and Constructional Generation of harmonics and switching surges in a
Features of Induction Motors static device switching circuit . Protection of
lntroduction . Brief theory of the operation of a semiconductor devices and motors . Energy
polyphase motor. Motor output and torque . Motor conservation through solid-state technology .
ratings and frame sizes . Preferred ratings at different Application of static drives . Speed variation through
voltages . Influence of service conditions on motor variable-speed fluid couplings . Static drive versus fluid
performance . No-load performance . Effect of steel of coupling . D.C. drives Braking . Induction generators
laminations on core losses . Circle diagram . Types of ' Inching or jogging . Number of starts and stops
induction motors . Mounting of motors Enclosures *
Weatherproof motors (WP) . Degree of protection . 7 Special-Purpose Motors
Cooling systems in large motors . Single phase Textile motors . Crane motors . Determining the size
motors Theory of operation of motor . Sugar centrifuge motors Motors for deep-
well pumps . Motors for agricultural application .
2 Motor Torque, Load Torque and Selection Surface-cooled motors 8 Torque motors or actuator
of Motors motors . Vibration and noise level . Service factors .
Motor speed-torque curve . NEMA rotor designs . Motors for hazardous locations . Specification of
Special designs of rotors . Effect of starting current on motors for Zone 0 locations . Specification of motors
torque . Load torque or opposing torque 1 Selection of for Zone 1 locations . Motors for Zone 2 locations .
motors . Time of start-up and its effect on motor Motors for mines, collieries and quarries . Intrinsically
performance . Thermal withstand time safe circuits, type Ex. 'i' . Testing and certifying
authorities . Additional requirements for ciritical
3 Duties of Induction Motors installations Motors for thermal power station
Duty cycles Continuous duty (CMR) (SI) Periodic auxiliaries . Selection of a special-purpose motor
duties . Factor of inertia (FI) Heating and cooling
characteristic curves ' Drawing the thermal curves . 8 Transmission of Load and Suitability of
Rating of short motors . Equivalent output of short Bearings
time duties . Shock loading and use of a flywheel Direct or rigid couplings . Flexible couplings .
Delayed-action couplings . Construction and principle
4 Starting of Squirrel Cage Induction Motors of operation . Belt drives . Checking the suitability of
Direct on-line starting (DOL) . Reduced voltage starting bearings . Suitability of rotors for pulley drives
5 Starting and Control of Slip-ring Induction 9 Winding Insulation and its Maintenance
Motors Insulating materials and their properties . Ageing of
Important features of a slip-ring motor . Starting of slip- insulation . Practices of insulation systems . Procedure
ring motors . Hypothetical procedure to calculate the for vacuum pressure impregnation . Maintenance of
insulation . Monitoring the quality of insulation of HT
rotors resistance. Speed control of slip-ring motors '
Moving electrode electrolyte starters and controllers formed coils during manufacturing