MG 2-2001
Page ii
© Copyright 2001 by the National Electrical Manufacturers Association.
5.4
Thermal Protection ............................................................................................................10
5.5 Impedance Protection........................................................................................................10
5.6 Overspeed .........................................................................................................................10
5.6.1 Induction Motors...................................................................................................10
5.6.2 Direct-Current Motors...........................................................................................11
5.6.3 Alternating-Current Series and Universal Motors .................................................12
5.6.4 Synchronous Motors.............................................................................................12
5.6.5 Synchronous Generators......................................................................................12
5.6.6 Direct-Current Generators....................................................................................12
6. SAFETY IN MACHINE APPLICATION..........................................................................................12
6.1 Matching of the Machine to the Load ................................................................................13
6.2 Degree of Machine Enclosure ...........................................................................................13
6.2.1 General.................................................................................................................13
6.2.2 Application in Residences and in Places Regularly Open to the Public ...............13
6.2.3 Applications in Places Restricted to Persons Employed on the Premises ...........14
6.2.4 Application in Places Accessible Only to Qualified Personnel .............................17
6.2.5 AC Motors For Class I, Division 2, Hazardous Locations.....................................17
6.3 Proper Selection of Machines............................................................................................18
6.3.1 Variation From Rated Voltage and Rated Frequency...........................................18
6.3.2 Usual Service Conditions .....................................................................................21
6.3.3 Unusual Service Conditions .................................................................................22
6.3.4 Speed Limitation...................................................................................................22
6.3.5 Operation of Direct-current Motors on Rectified Alternating Current....................23
6.3.6 Shaft Loading .......................................................................................................24
6.3.7 Transient Torques ................................................................................................24
6.3.8 Torsional Vibration................................................................................................24
6.3.9 Torque Pulsations During Starting of Synchronous Motors..................................25
7. SAFETY IN MACHINE INSTALLATIONS .....................................................................................25
7.1 Installation and Protection .................................................................................................25
7.2 Grounding..........................................................................................................................25
7.3 Wiring Connections ...........................................................................................................25
7.4 Flammable Materials .........................................................................................................26
7.5 Rotating Parts....................................................................................................................26
7.6 Maximum Speed of Drive Components.............................................................................26
7.7 Lifting of Machines.............................................................................................................26
7.8 Surface Temperatures.......................................................................................................28
7.9 Hold-down Bolt Sizes.........................................................................................................28