protection of electric motors

... design constraints of explosion-proof motors (such as increased air gap, reduced starting current, and enhanced sealing) have a negative impact on efficiency Geared motors and brake motors are included, ... percentage of total losses, are assumed as in Figure Using (1) and (2), three cases were analyzed in terms of efficiency gains by means of losses reduction: n Case 1: elimination of rotor electric ... 2.1–2.22 chronous motors for cost reasons can [18] M Melfi, S Evon, and R McElveen, “InIMPORTANCE OF duction vs permanent magnet motors, ” IEEE now profit from the advantages of PM Ind Applicat...

Ngày tải lên: 26/11/2015, 09:42

Ngày tải lên: 08/06/2016, 07:12

... 10.51n Kirchhoff’s law, 1.16, 1.91 in analysis of dc series motors, 4.14 in analysis of PMDC motors, 4.42 in analysis of single-phase motors, 6.13, 6.74 in analysis of three-phase motors, 10.107 ... E motors in PMDC motors, 4.45–4.46, 4.115 in polyphase motors, 6.100 in series dc and ac motors, 4.128–4.130 in single-phase motors, 6.56 in switched-reluctance motors, 5.102 in synchronous motors, ... University He has worked in sales of servo electric motors at Moog, Inc., and in sales of specialty motors at Doerr Electric He is currently the vice president of Oven Systems, Inc ANDREW E MILLER...

Ngày tải lên: 27/06/2014, 15:20

... University He has worked in sales of servo electric motors at Moog, Inc., and in sales of specialty motors at Doerr Electric He is currently the vice president of Oven Systems, Inc ANDREW E MILLER ... from the University of Illinois He is a senior member of IEEE and an associate editor of the IEEE Transactions of Industrial Electronics He is the author of numerous articles on motors and motion ... Library of Congress Cataloging-in-Publication Data Handbook of small electric motors / William H Yeadon, editor in chief, Alan W Yeadon, associate editor p cm ISBN 0-07-072332-X Electric motors, ...

Ngày tải lên: 11/08/2014, 07:23

... 10.51n Kirchhoff’s law, 1.16, 1.91 in analysis of dc series motors, 4.14 in analysis of PMDC motors, 4.42 in analysis of single-phase motors, 6.13, 6.74 in analysis of three-phase motors, 10.107 ... E motors in PMDC motors, 4.45–4.46, 4.115 in polyphase motors, 6.100 in series dc and ac motors, 4.128–4.130 in single-phase motors, 6.56 in switched-reluctance motors, 5.102 in synchronous motors, ... Electronically commutated motors: brushless dc (BLCD) motors, 5.1–5.46 step motors, 5.47–5.99 switched-reluctance motors, 5.99–5.107 Electrons: magnetic moment of orbit, 1.62 magnetic moment of spin, 1.5,...

Ngày tải lên: 11/08/2014, 07:23

... Inertia moments of polar moments of Inertia of masses, polar moments of Institute of Electrical and Electronics Engineers (IEEE) Institute of Industrial Engineers (IIE) Instrument Society of America ... quantities of Magnets electropermanent Magnification, closeup lenses Malleability Manganese Mass moments of inertia of complex polar moments of inertia of radius gyration of units of MathCad ... conversion table Conductors electrical electrical clearances of forces in ac circuit forces in dc circuit properties of metals used for Cones frustrum of mensuration of Constants physical Conversion...

Ngày tải lên: 11/08/2014, 07:23

... Electronically Commutated Motors 5.1 5.1 Brushless Direct-Current (BLDC) Motors / 5.1 5.2 Step Motors / 5.47 5.3 Switched-Reluctance Motors / 5.99 Chapter Alternating-Current Induction Motors 6.1 6.1 Introduction ... Induction Synchronous Motors / 7.1 Hysteresis Synchronous Motors / 7.5 Permanent-Magnet Synchronous Motors / 7.9 Performance Calculation and Analysis / 7.16 Chapter Application of Motors 8.1 Motor ... Selection of Short-Circuit Protection and Control for Design E Motors / 10.51 Switched-Reluctance Motor Controls / 10.65 Basic Stepping-Motor Control Circuits / 10.70 Current Limiting for Stepping Motors...

Ngày tải lên: 11/08/2014, 07:23

... five of the flux paths for a typical air gap between two pieces of steel The total permeance of the air gap is equal to the sum of the permeances for the parallel flux paths The permeance of each ... (see Fig 1.1) The thumb of your right hand is pointed in the direction of the current, where current is defined as the flow of positive charge from + to − The fingers of your right hand curl ... length l In the electrical analogy, a voltage V provides the electromotive force that pushes an electrical current I through a region The amount of magnetomotive force required per unit of magnetic...

Ngày tải lên: 11/08/2014, 07:23

... the final annealing of laminations punched from semiprocessed electrical sheets Other types of annealing that enhance the quality of laminations are the stress relief annealing of laminations punched ... loss of 29-gauge silicon-iron electrical steels at 60 cps MATERIALS FIGURE 2.55 Core loss of 26-gauge silicon-iron electrical steels at 60 cps 2.39 2.40 FIGURE 2.56 CHAPTER TWO Core loss of 24-gauge ... silicon-iron electrical steels at 60 cps MATERIALS FIGURE 2.57 Core loss of 29-gauge silicon-iron electrical steels at 50 cps 2.41 2.42 FIGURE 2.58 CHAPTER TWO Core loss of 26-gauge silicon-iron electrical...

Ngày tải lên: 11/08/2014, 07:23

... dry ice temperature of −75°F and an oven temperature of 650°F This allows for the extremely fast warming of the shaft and cooling of the rotor while assembling A minimum of 0.003 in clearance ... consists of inserting a first layer of wire into a slot, compacting or deforming the wires into the back of the slot to fill all of the void spaces between wires, then inserting a second layer of wire ... designs Producing finished stacks of rotor and stator laminations in the die has many advantages to the manufacturers of electric motors, particularly the elimination of downstream manual or mechanical...

Ngày tải lên: 11/08/2014, 07:23

... distance Ra2 = radius of the circle on which the arc segments of the bottoms of the slots are centered Nat = number of armature teeth Lstk = length of the armature stack θpole = angle of pole arc 4.50 ... mechanical output + rotational losses electrical power output Electrical efficiency = ᎏᎏᎏᎏᎏ electrical power output + electrical losses (4.32) (4.33) DIRECT-CURRENT MOTORS FIGURE 4.17 4.17 Losses in ... circuit, the transient response of the series motor can be calculated 4.1.3 Permanent-Magnet DC Motors (Shunt PM Field Motors) The general equivalent electrical circuit of a PMDC motor and its physical...

Ngày tải lên: 11/08/2014, 07:23

... between electrical and mechanical degrees for any four-pole design Degrees electrical = degrees mechanical × number of pole pairs ∴ Degrees electrical = 24° × = 48° electrical (5.7) A 48° electrical ... the number of phases, which is three here Next in importance is the number of poles The use of two poles is waning, and the use of six or eight poles is increasing Four-pole BLDC motors are among ... variable winding pitches: number of stator slots VSP1 = ᎏᎏᎏ + number of poles number of stator slots VSP2 = ᎏᎏᎏ − number of poles (5.3) VSP1 = and VSP2 = The average of these two variable-pitch coils...

Ngày tải lên: 11/08/2014, 07:23

... diameter of stator D2 = outside diameter of rotor Da = diameter of mean air gap Di = inside diameter of resistance ring Dr = mean diameter of end ring Dring = diameter of resistance ring at center of ... pole of primary tooth ATt2 = ampere turns per pole of secondary tooth At1 = area of primary tooth At2 = area of secondary tooth B = coil span Bt1 = density of primary tooth Bt2 = density of secondary ... = physical length of air gap Lmet = length of mean end turn Lt1 = length of primary teeth Ly1 = length of primary yoke Ly2 = length of secondary yoke lg = effective length of air gap MTL = mean...

Ngày tải lên: 11/08/2014, 07:23

... way Other PM synchronous motors are essentially PM stepper motors run as PSC motors The motor shown in Fig 7.19 has a stator consisting of two sets of coils with the teeth offset from each other ... length of air gap Lmet = mean end-turn length of coil Ls = stator stack length lg = effective length of air gap Lt1 = length of teeth Ly1 = length of yoke MTL = mean turn length m = number of phases ... distribution of magnetic stator poles FIGURE 7.19 Permanent-magnet synchronous motor SYNCHRONOUS MACHINES FIGURE 7.20 Half-tooth-pitch offset consisting of two sets of coils with offset teeth...

Ngày tải lên: 11/08/2014, 07:23

... Classification of insulation systems DC motors and generators AC motors and generators AC generators and synchronous motors Single-phase motors Motors for hermetic refrigeration compressors Small motors ... percent of peripheral speed of core 8.19 APPLICATION OF MOTORS TABLE 8.9 Weights and Thermal Properties of Materials Pe lb/in3 Material Aluminum, commercial Copper, commercial Steel, solid, electrical ... 8.16 Dissipation of heat from the surface of a 25-in-diameter 36in-long rotor (From Packer, 1951.) 8.24 APPLICATION OF MOTORS FIGURE 8.17 Dissipation of heat from the surface of a 25-in-diameter...

Ngày tải lên: 11/08/2014, 07:23

... IP Nomenclature—Degrees of Protection Indicated by the Second Characteristic Numeral Degree of protection of equipment Second characteristic numeral Degree of protection of equipment Brief description* ... operation of the machine 6§ Machine dust-tight No ingress of dust * This description should not be used to specify the form of protection † Machines assigned a first characteristic numeral of 1,2,3, ... application of the tests in IEC Publication 68 to simulate the effects of storage IEC 529 Degrees of protection provided by enclosures (IP code) DRIVES AND CONTROLS IEC 34-5 10.5 Classification of degrees...

Ngày tải lên: 11/08/2014, 07:23

... The slope of the curve in this region is called the recoil permeability This is the normal region of use of the magnet (along the line of recoil permeability, through and on both sides of Br) If, ... passing a pulse of electrical current through a conductor of copper wire, producing a magnetic field in the vicinity of the wire for a short time The wire may be coiled in a number of turns, to ... in spite of the high cost of this material The magnetizing information of the part of the B-H curve may be redrawn in intrinsic form (that is, the coercive field times the permeability of free...

Ngày tải lên: 13/08/2014, 05:20

... common type of winding for PMDC motors The lap winding is also used in motors having more than two poles, but one pair of brushes is required for each pair of poles The number of pairs of brushes ... the sides of the straight edges of the magnet and into the housing: Plma = (1.04)KmlLma (4.407) The leakage factor is the ratio of the sum of all permeance factors to the sum of all of the useful ... length (thickness) of the magnet Lg = length of the air gap in the radial direction Am = area of the magnet Ag = area of the air gap (4.378) DIRECT-CURRENT MOTORS 4.99 The area of the magnet is...

Ngày tải lên: 13/08/2014, 05:20

... section provides examples of the value of sound, vibration, and current spectral analysis for electric motors Since spectral analysis encompasses a tremendous range of diverse technical areas, ... potential field failures Regardless of the type of test, documentation of failed parts should include the percentage of adhesive or substrate failure and the percentage of adhesive coverage at the joints ... less than a third of single-shift test duration Manual spectral analysis can require hours or days of detailed analysis on a limited number of motors, especially for brush dc gear motors In contrast,...

Ngày tải lên: 13/08/2014, 05:20

... repair, and rewind of horizontal and vertical induction motors and synchronous machines.” Recognizing that there are certain specialized niche categories of electric motors, each of which has unique ... Members of the IEEE Bonnett is a Life Fellow of the IEEE Lockley is a Fellow of the IEEE This article first appeared as “Revisions to IEEE 1068: Standard for the Repair of AC Electric Motors in ... Practice for the Repair of Rotating Electrical Apparatus, ANSI/EASA AR100-2006 [10] C Yung, “Opportunities to improve reliability and efficiency of existing medium-voltage electric motors, ” in Proc...

Ngày tải lên: 26/11/2015, 09:41