Document KJY2KZ9q1yMJbjGJ8jeMr1rJr

860 CHAPTER 39 1951 Guide motor line contactor to drop out on low voltage, but prevents restarting when the voltage returns to normal except by the action of an operator. This latter type of protection is desirable where it is necessary for the operator to make initial starting adjustments on the machine. Manual control for an alternating or a direct current motor is usually located near the motor. When so located an operator must be present to start and stop or change the speed of the motor by operating the control mechanism. Manual control is sometimes employed only as a device to give overload protection and another device is employed to start and stop the motor. Manual control is used particularly on small motors which operate unit heaters, small blowers, and room coolers in an air conditioning system. In other cases manual control in the form of drums, when used with multi-speed motors, is only used as a speed setting device, while the starting and stopping functions operate automatically through thermostats and pressure switches. Because of the increasing complexity of air conditioning systems, the equipment is operated preferably by automatic control, and less dependence is placed on manual operation and regulation. Automatic control of motor starters may be accomplished by the use of remote push button stations, by a thermostat, float switch, pressure regulator, or other similar pilot devices. An added advantage of auto matic control is that the mam wiring for the starter may be installed near the motor, while the starter may be operated by a control device located elsewhere. TYPICAL MOTOR AND CONTROL SPECIFICATIONS Specification A. Typical Specifications fob d-c Motors (Constant (Shunt (1151 ......... Hp, .... .......RPM. -(Adjustable Speed, -(Compound Wound, 230 Volts [Varying (Series 600 d-c Motors for Driving ........................................... Motor Shall Be Arranged for (Application) {vertical*'^} Mounting and Shall Be Provided with a.............................................. 1' (Open, Splashproof, etc.) Type of Enclosure, NEMA {q|^ g} Insulation, and {gi^?ave} Bearings. \ Specification B. Typical Specifications fob d-c Motor Control Constant Control for Adjustable Speed d-c Motors Shall Be {Magnetic} and ShaI1 Adjustable Varying: Consist of a {circuit^Breaker} and 1111 nclse<f Controller Providing Overload Protection and Low Voltage {j{^ig^'0n}] Specification C. Typical Specifications for Squirrel-Cage Motors '208) ..Hp............. ......... ...RPM, {2} Cycles, m\ VoIts> |J Phase, 550J Motors and Motor Controls 861 Squirrel-Cage Induction Motors of the NEMA 'Design A--Normal Starting Torque, Starting Current Above NEMA Value" Design B--Normal Starting Torque, NEMA Starting Current Design C--High Starting Torque, NEMA Starting Current I Type** Design D--High Slip High Starting Torque J Driving (Application) Motor Shall Be Arranged for {verS^'} Mounting and Shall Be Provided with a ....................................Type of Enclosure, NEMA (Open, Splashproof, etc.) {|"a b} Insu,ation, *d {f^TM} Bearings. Refer to section on Alternating Current Motors for explanation of types. Specification D. Typical Specifications for Wound Rotor Motors 208] .Hp,................RPM, {^} Cycles,- Volts, {1} Phase, Wound Rotor 550j Induction Motors for Driving............................. Motor Shall Be Arranged for (Application) fHomontan Mounting and shall Be Provided with a................................. . \Vertical J (Open, Splashproof, etc.) Type of Enclosure, NEMA {5^ gjInsulation and {|^ve} Bearings. Specification E. Typical Specifications for Synchronous Motors Hp,.........RPM, Percent P.F., .. .Volts, {1} Phase, {go} Cydes, Belted 1 Synchronous Motors of the Coupled ] Type for Driving................................ Engine J (Application) Motor Shall Be Arranged for {vertical^} Peration and sha11 Be Provided with .......................................................... Type of Enclosure. Motor Shall Be Capable (Open, Splashproof, etc.) _ ,_ ,, ,,T of Developing a Starting Torque of ...... Percent Full Load Torque, a Pull-In Torque of .. . Percent Full Load Torque, and a Pull-Out Torque of ......... Percent Full Load Torque. The Motor Field Shall Be Excited from a (Direct Connected Exciter' J Belted Exciter |M-G Set Exciter Which {|j]a|j jjot} Be Included with the Motor. (d-c Bus Specification F, Typical Specifications for Single Phase Motors .......Hp,................ RPM, {j^j} Cycles, {^} Volts, Single Phase Motor of the............. ...................... Type for Driving ................1... Motor Shall (Capacitor, Split Phase, etc.) (Application)