Document dD928eM2wZm2RgB8MnB2zdg3Q

692 CHAPTER 35 1949. Guide Table 7. Typical Specifications fob Synchronous Motors Hp,.........RPM,......... Per Cent P.F.,......... Volts, ||j Phase, Cycles, Belted Synchronous Motors of the Coupled Type for Driving. Engine (Application) Motor Shall be Arranged for {verticS^} Operation and Shall Be Provided With A.................... . ..........................Type of Enclosure. Motor Shall be Capable (Open, Splashproof, etc.) of Developing A Starting Torque of........ Per Cent Full Load Torque, A Pull-In Torque of.........Per Cent Full Load Torque, And A Pull-Out Torque of........... Per Cent Full Load Torque. The Motor Field Shall Be Excited From A (Direct Connected Exciter] J Belted Exciter 1M-G Set Exciter I I Which (d-c Bus J Be Included With The Motor. Table 8. Typical Specifications for Single Phase Motors ................Hp.................. RPM, Cycles, {230} Volts, Single Phase Motor of the.......................................Type for Driving ................. ....... Motor Shall (Capacitor, Split Phase, etc.) (Application) Be Arranged for jvertfcS^} Mounting And Shall Be Provided With Wi sa- **01 tas b} i-*** *- {ISv.}8"TM1' Table 9. Typical Specifications for Squirrel-Cage Motor Control Control for Squirrel-Cage............ ..... ........Motors Shall Consist of An Enclosed (Fan, Pump, etc.) ffiSSL) ^ {SeM barter Providing Overload Protection And Low Voltage Control Shall Include A Safety Disconnect Switch {fgrC^^Endosure} With the Starti^ droller. Multi-Speed control may be either manual or magnetic, and at full or reduced voltage. When using automatic magnetic control with two-, three-, and four-speed separate winding or consequent pole motors, con trol may. be obtained from a remote point by means of a push button master switch. The various speeds of the motor are obtained from the master switch by simply depressing the correct push button. This is Motors and Motor Controls ... 693' known as selective speed control. It is commonly used in' the' smaller theater installations where the fan and motor are located backstage and the speed control is located in the lobby. Multi-speed motor controllers may be provided with compelling relays which make it necessary for the operator to press the first speed button before regulating the motor to the desired speed. This insures that the motor is always started at low speed before adjusting to a higher speed. Timing relays which provide for automatic acceleration may be used for control. With this feature the motor will always start at low speed and automatically accelerate to the desired speed. Decelerating relays may be used to reduce the shock effect of the braking action to the motor and drive when the speed is reduced from a higher to a lower speed. Single Phase motor control usually consists only of a linestarter, either ACROSS THE LINE STARTING LINE LINESTARTER REDUCED VOLTAGE STARTING LINE LINE Arrangements 2, 3,-4 and 6 provide automatic push-button starting. Fig. 11. Recommended Controls for Squirrel-Cage Motors manual or magnetic. In some cases it is desirable also to provide a dis connect switch. Fig. 13 illustrates the recommended controls. Typical specifications for single phase motor control are. shown in Table 12. GEAR MOTORS A gear motor is a self-contained combination of any Type of a-c or d-c motor and an enclosed speed-reducing gear, providing a more compact and readily adaptable unit than is obtained by using a motor, coupled to! a gear reducer. Gear motors are available in sizes up to 75 hp with output, shaft speeds from about 4 to 1430 rpm, making it possible to couple or to connect .by gear or chain to nearly any machine. High speed motors are used, generally 1800 rpm on 60 cycles, thus obtaining the advantages of .