Deep bar and double cage rotor pdf download

Performance analysis of three phase squirrel cage induction. Introduction as stated in prior research l, 2, while starting up the deepbar and doublesquirrelcage. It is usually designed for fixedspeed operation, larger ratings having such features as deep rotor bars to limit direct on line dol. As the name indicate the double cage induction motor has two winding in rotor. The sliptorque curve for deepbar rotor is shown below along with the deepbar stator. As the name indicates, the double cage induction motors have two cages in the rotor and they have the advantages of both squirrel cage induction motors and wound rotor induction motors. The double cage behaves like a deep bar cage electric. Select current density in rotor bars and end rings depends on ambient temp, cooling conditions, and duty cycle, and from rotor bar and end ring currents get their cross sectional areas. Pdf the model of doublecage induction motor for the. On the other hand, the inner cage consists of rotor bars having high reactance and low resistance. The parameters are estimated either in the transient state or in the steady state by using a curve.

The model of doublecage induction motor for the analysis. The figure below shows a deep bar cage rotor with deep and narrow bars. Both rotor types can be effectively modeled using two windings perphase in the rotor. Can any body advise me of a straightforward method of converting these parameters to the resistance and reactance of a double cage induction motor, which has a torque speed curve similar to that of the deep bar machine. Advantage of double cage rotor over single cage rotor. The induction machines design handbook 2nd edition ion. Torquespeed curves influence of rotor parameters 211 cage rotor 211 double cage rotors 2 deep bar rotors 214 starting and runup of slipring motors 215 influence of supply voltage on torquespeed curve 217 generating and braking 218 generating region overhauling loads 219 plug reversal and plug braking 220 injection braking 221. More emphasis should be put on the acquisition of an inrushstart. Now consider that the bar consists of many number of layers. Now that you know some of the design characteristics of the double cage rotor, are there any special considerations that should be given for testing. A double cage rotor has essentially two parallel rotor bar circuits built into the rotor. The model is based on approximate analysis of the airgap.

There is no constructional difference between stator of seep bar rotor motor and that of ordinary induction motor. Pdf the model of doublecage induction motor for the analysis of. The resistance of the upper cage winding is more than the inner c. The rotor consists of deep bars, short circuited by two end rings one on each side. In some applications, very high starting torquetstarttrated. Current versus speed characteristics, double cage rotor, induction motor. More emphasis should be put on the acquisition of an inrushstartup test as a baseline. Parameter estimation for a deepbar induction motor. This arrangement is used for obtaining high starting torque at a low value of starting current. The starting cage features a large active resistance and low leakage reactance, whereas the operation cage oppositely shows low active resistance. The deep bar rotor has a single cage, usually of copper, formed in slots which are deeper and narrower than in a conventional singlecage design. Based on the influence of the skin effect over electrical rotor parameters can be constructed a mathematical mode.

Double cage rotor of an induction motor a double cage induction motor is that type of motor in which a double cage or two rotor windings or cages are used. Double cage rotor of an induction motor circuit globe. The net reactance of deep bar rotor at standstill is higher than that in a normal bar design. An induction motor or asynchronous motor is an ac electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding.

Introduction as stated in prior research l, 2, while starting up the deep bar and double squirrel cage motors with soldered rotors, the squirrel cage winding is the component most vulnerable to damage. It is usually designed for fixedspeed operation, larger ratings having such features as deep rotor bars to limit direct on line dol starting currents. The deep bar rotor has a single cage, usually of copper, formed in slots which are deeper and narrower than in a conventional single cage design. Pdf electric machines by dp kothari and ij nagrath pdf download. An induction motor can therefore be made without electrical connections to the rotor. The electrical machines ii notes pdf em ii pdf notes em ii notes pdf file to download are listed below please check it. Mar 25, 2017 in some applications, very high starting torquetstarttrated. Double cage induction motor electrical engineers guide. The squirrel cage winding in this design consists of two layers of bars shortcircuited by end rings.

Apr 17, 2015 the sliptorque curve for deep bar rotor is shown below along with the deep bar stator. The deep bar and double cage rotor are used to increase starting torque of squirrel cage induction motor. Dec 27, 2015 an induction motor with two cage rotor is used for high starting torque. As stated in prior research l, 2, while starting up the deepbar and doublesquirrelcage. Double cage rotor induction motor twinslot cage rotor double slot rotors as well as double cage rotors form the category of twinslot cage rotors. If an induction machine with closed or skewed rotor slots is studied, the model for saturation should be extended. An induction motors rotor can be either wound type or squirrelcage. In this small post we will discuss about the double cage induction motor in brief. Double cage and deep bar squirrel cage rotor induction motor. Nema class b design has large and deep rotor bars accommodated. Deepbar model the mathematical approach in terms of modeling for a deepbar and doublecage rotor construction is similar. A twophase dynamic induction motor model is derived which includes the effects of rotor bar eddy currents and leakage inductance saturation. Double cage rotors free download as powerpoint presentation.

This includes the starting and running values of the rotor single cage equivalent circuit. It has been proved that it behaves like a deep bar cage, but it produces even higher starting torque at lower starting current. Classes a and b have similar torquespeed characteristics. Double cage induction motor introduction diy electrical. Double cage rotor a rotor design, which though more expensive gives still better starting, and running performances than the deep bar design, is the double cage rotor. Nov 01, 2004 broken bars cause torque and speed oscillations in the rotor, provoking premature wear of bearings and other driven components. Cage rotor 211 double cage rotors 2 deep bar rotors 214 starting and runup of slipring motors 215 influence of supply voltage on torquespeed curve 217 generating and braking 218.

Torqueslip characteristics covering motoring, generating and braking regions of operation, induction generator, noload and blocked rotor tests, circle diagram and therefrom performance evaluation of the motor, cogging and crawling, equivalent circuit and performance of doublecage and deepbar motors. Deep bar rotor the deep bar rotor in an induction motor is used to obtain high rotor resistance at starting and low rotor resistance at the running condition. What are the merits and demerits of singlecage and double. The invention relates to a cage rotor for an asynchronous machine 1 comprising starting bars for improving the starting behavior. Harley and yao duan georgia institute of technology november, 2009. The higher valued rotor resistance results more torque to be developed at the starting. The double cage rotor has two cages in which rotor winding is accommodated. Starting performance torque of induction machine has improved.

Pdf electric machines by dp kothari and ij nagrath pdf. The model of doublecage induction motor for the analysis of thermal fields in transient operations. The changes are made keeping the original flavor of the book intact, that is, indepth coverage of fundamental concepts. One set is deeper closer to the shaft and the other set is commonly smaller and shallower closer to the. The rotor of of an induction motor can be designed in two types. Class b has large and deep rotor bars, that is, the skin effect cannot be neglected during startup. Pdf skin effect modelling in induction motors rotor deep bars. Electric machines by dp kothari and ij nagrath now in its 5.

This simplest form of ac induction motor or asynchronous motor is the basic, universal workhorse of industry. Electrical machines 2 pdf notes em 2 pdf notes smartzworld. The rotor is connected to the mechanical load through the shaft. What is a double cage rotor, part 2 in the january 5, 2010 tip we discussed what a double cage rotor is. The skin effect is mostly relevant in the case of deep rotor bars and a doublecage structure. When the speed of the rotor of the deep bar double cage induction motor increases, the frequency of the induced emf and current in the rotor gets gradually decreased. These machines, because of their rotor bar design, exhibit a high rotor resistance to the flow of negative sequence currents and produce extreme heating during unbalanced conditions. Electric motors and drives fundamentals, types and applications third edition austin hughes. Double cage equivalent of deep bar rotor motor electric. The model of double cage induction motor for the analysis of thermal fields in transient operations. The model of doublecage induction motor for the analysis of. The sliptorque curve for deep bar rotor is shown below along with the deep bar stator. A triple cage circuit of a deep bar induction motor is numerically identified in the time domain. A doublecage rotor has essentially two parallel rotor bar circuits built into the rotor.

Dec 26, 2015 in this small post we will discuss about the double cage induction motor in brief. The magnetic leakage flux lines are shown by dotted lines. An induction motor model with deepbar effect and leakage. Double cage and deep bar squirrel cage rotor induction. This paper presents a doublecage induction motor model for analysis of thermal fields in transient operation. Three phase squire cage induction motor, fully enclosed. Smallsignal model for saturated deepbar induction machines. Squirrel cage motors are the most commonly used induction motors, but the main drawback in them is their poor starting torque due to low rotor resistance. Massachusetts institute of technology cambridge, massachusetts, 029, usa. The outer bars consists of rotor bars having low reactance and high resistance. Mar 04, 2016 the squirrel cage induction motor is widely used rotor copper losses are high and hence less efficiency less rotor copper losses and hence high efficiency speed control by rotor resistance method is possible speed control by rotor resistance method is not possible slip ring induction motor are used where high starting torque is required i.

Traditional design of cage rotor induction motors ronald g. Slip ring rotor for both of them the stator part connection is same. An induction motor with two rotor windings or cages is used for obtaining high starting torque at low current. The invention further relates to a method for producing such a cage rotor. As the name indicates, the double cage induction motors have two cages in the rotor and they have the advantages of both squirrelcage induction motors and wound rotor induction motors. One set is deeper closer to the shaft and the other set is commonly smaller and shallower closer to the stator.

These drawbacks are removed by a double squirrel cage motor, which has high starting torque without sacrificing efficiency. Sep 18, 2019 the deep bar and double cage rotor are used to increase starting torque of squirrel cage induction motor. Detecting broken rotor bars prevents catastrophic damage. Indirect vector control of multi cage induction motor citeseerx. Redistribution of current in deep bar cage rotors as a result of. Generally in induction motor related operations, squirrel cage induction motors are widely used.

Study of double cage induction motors with different rotor bar materials. This reduces the evidence of a faulty rotor bar and may. The squirrel cage with deep rotor bars can be equivalent with a double cage, one of these cages having constant parameters 8. Designing squirrel cage rotor slots with high conductivity james l. Deep bar or double cage rotors are used in squirrel cage. Diagnosis and fault detection in electrical machines and. Three double rotor bar induction motors have been simulated and their. The parameters are estimated either in the transient state or. Deep bar or double cage rotors are used in squirrel cage induction motor to obtain published on 27 oct 15. Consequences of broken rotor bars rotor windings in squirrel cage induction motors are manufactured from aluminum alloy, copper, or copper alloy. Jul 06, 2017 squirrel cage motors are the most commonly used induction motors, but the main drawback in them is their poor starting torque due to low rotor resistance. Another phenomenon that is usually omitted within the smallsignal analysis is the skin effect of rotor bars. Designing squirrel cage rotor slots with high conductivity. For the case when skin effect can be neglected in both cages, let us.

Construction is simpler and therefore cheaper than in a doublecage rotor, as shown on the right in fig. At startup, the reactance of these bars is large compared to the resistance, resulting in. It is seen that the top most layer element a is linked with minimum leakage flux and therefore its leakage inductance is minimum. In pdmas january 5 tip, the company discussed what a doublecage rotor is. Improvements in deep bar rotor induction motors us3290526a. Im design above 100kw and constant v and f size your own im high voltage stator design. Deep bar cage rotor figure below shows a cage rotor with deep and narrow bars. A bar may be assumed to be made up of number of narrow layers as shown in fig. The double cage behaves like a deep bar cage electric equipment. In this paper, a new diagnostic index that allows the extraction of rotor fault components issued from axial vibration signals, is defined to improve the fault quantification procedure. Construction is simpler and therefore cheaper than in a double cage rotor, as shown on the right in fig. Large air pockets in diecast aluminum alloy rotor windings can cause nonuniform bar expansion leading to rotor bending and imbalance that causes high vibration levels from premature bearing wear.

One can not even add external resistance for starting of purposes, as the rotor bars are permanently short circuited construction of a squirrel cage rotor is here. Introduction as stated in prior research l, 2, while starting up the deep bar and double squirrel cage. A triplecage circuit of a deepbar induction motor is numerically identified in the time domain. In a slip ring induction motor, the rotor resistance is a. May 02, 2016 before answering the question we have to know about types of rotors in induction motors. The stator of a double cage induction motor is similar to that of ordinary induction motor. This article presents a way to analyze the skin effect, in the deep bars of induction motors im. Before answering the question we have to know about types of rotors in induction motors. High during starting and low at normal operating speed. The rotor of the three phase induction motor are further classified as squirrel cage rotor, slip ring rotor or wound rotor or phase wound rotor. Gersh, finite element calculation of double cage rotor equivalent circuit parameters, ieee trans. Ac motors, heating, induction motors, squirrel cage motors, temperature rise 1.

Deepbar cage rotor figure below shows a cage rotor with deep and narrow bars. The slotting arrangement for double cage induction motor is as shown in above figure. Us20120187796a1 us391,147 us2010391147a us2012187796a1 us 20120187796 a1 us20120187796 a1 us 20120187796a1 us 2010391147 a us2010391147 a us 2010391147a us 2012187796 a1 us2012187796 a1 us 2012187796a1 authority us united states prior art keywords operating bars operating bars cage rotor material prior art date 2009. Vibration signature analysis for rotor broken bar diagnosis. This paper presents a doublecage induction motor model for ana lysis of thermal. The stator of a double cage rotor of an induction motor is same as that of a normal induction motor.