Induction Motor Rewinding Calculation

Posted By admin On 03/09/21

An electrical motor is one kind of machine which is used to change the energy from electrical to mechanical. Most of the motors work on the principle of interaction among the electric current as well as the magnetic field within a wire winding. This can generate force in the form of shaft rotation. These motors can be powered with DC or AC sources. The DC sources are batteries whereas the AC sources are inverters, power grids, generators. A generator is mechanically similar to the motor but works in the reverse direction by converting the energy from mechanical to electrical. An electric motor can be built with the rotor, stator, air gap, windings, bearings, & commutator. The classification of motors can be done with considerations like the type of power source, construction, motion output type, and applications. This article discusses what is a motor winding, types, and its calculation.

Principle-of-three-phase-induction-motor/ Per-phase equivalent circuit. Motor Slip. R 1 and R 2: stator and rotor winding resistances. X 1 and X 2. Allowable current density is not a random choice. It is directly related to the temperature of the conductor and is dependent on the insulation (on the individual strand, on the turn, and on the completed coil), the method and efficiency of the cooling, the heat transfer properties of the surrounding magnetic materials, and the nature of the current itself (AC or DC). To rewind an electric motor, remove the motor's outer housing and use your hands to pull the armature out of the stator. Then, use a flat head screwdriver to pry open the tabs on the brush pads, and then cut through the wires and pull them out by hand. Induction Motor Equations ENGN1931F – Spring 2017 2 Let ω ω ω L R S and be the angular velocities of the magnetic field (line frequency), rotor, and slip respectively. For convenience we assume that ϕ= 0 at t = 0, which implies ϕ ω= R t and ω ω ω S L R= −. The flux in the single-turn coil on the rotor surface is.

What is Motor Winding?

Induction motor rewinding calculations

The electric motor winding definition is, windings in electric motors are wires that are placed within coils, generally enclosed around a coated flexible iron magnetic core to shape magnetic poles while strengthened with the current. Electric machines are available in two fundamental magnet field pole configurations namely salient pole as well as a non-salient pole. The motor winding diagram is shown below.

Induction

In the salient pole configuration machine, the magnetic field pole can be generated produced with a winding wound approximately under the pole face. In the non-salient pole configuration, the winding can be dispersed within slots of pole face. A shaded pole motor includes a winding which is placed around the pole part that holds up the magnetic field phase. Some kinds of motors include conductors with thicker metal like sheets of metal otherwise bars generally copper, otherwise aluminum. Generally, these are power-driven with electromagnetic induction.

Types of Motor Windings

The motor winding types are two types which include the following.

  • Stator Winding
  • Rotor winding

Based on the motor winding connection, armature windings are classified into two types which include the following.

  • Lap winding
  • Wave Winding

Stator Winding

The slot on stator core of the three-phase motor winding carries stator winding. This winding can be supplied with 3-phase AC supply. The motor winding in three-phase which is connected in star or delta form based on the type of starting method used.


The motor like squirrel cage can be frequently on track by the star to delta stator & thus the stator of the motor can be connected in delta. The slip ring 3-phase induction motor is in progress by including resistances, thus the slip ring induction motor’s stator winding can be associated in star otherwise delta form.

Whenever the stator winding is energized by 3-phase ac supply, then it generates a rotating magnetic field (RMF).

Rotor Winding

In a motor, the rotating part is known as the rotor. The rotor includes the rotor winding as well as rotor core. Download sony vegas pro 12 khg team patch. The rotor winding is energized by the DC supply. The rotor can be classified into two types namely the phase wound and the squirrel cage.

The squirrel cage rotor’s core is made up of cylindrical iron core which has a curved slot over the external surface on which the aluminum or copper conductors are located. These are short-circuited at the endings using the copper or aluminum rings.

Induction Motor Rewinding Calculations

The electromagnetic induction is the occurrence wherein the electromagnetic force is induced within the conductor which carries the conductor due to the variable magnetic field. When the current stimulates in the rotor then it causes the rotor to move.

Lap Winding

Lap winding is the one kind of armature winding. The conductor connection can be done where the lanes and poles are similarly connected. The final part of each armature coil is associated with the commutator. The number of brushes within winding is the same as the number of parallel lanes. These are divided equally into two polarity windings like positive & negative. The lap winding applications mainly involve in high current and low voltage machines. These windings are categorized into three type’s namely simplex, duplex and triplex type winding.

Wave Winding

Wave winding includes parallel lanes among the two brushed like positive & negative. The primary armature coil’s end part can be associated with the starting part of the next armature coil commutator part with some distance. The conductors in this type of winding can be connected with two parallel lanes in a machine pole. The number of parallel ports can be equal in the direction of the number of brushes, which is used for high-voltage, and low-current machines. Please refer to the link to know more about Lap Winding & Wave Winding.

Induction Motor Winding Calculation

Motor Winding Calculation

The motor winding wire calculation can be done using an ohmmeter. Connect the positive terminal of the multimeter which is in red color to the positive terminal of the windings of the motor. Similarly, connect the negative terminal which is in black color to the negative terminal of the windings of the motor. The reading of the motor winding machine can be displayed on the multimeter screen that is resistance in ohms.

With the help of Ohm meter, detach the power supply from the motor. Place meter on ohms and generally the range can be expected from 3 to 2 ohms. If we observe the reading like zero, and a short among phases occurs. Generally, if it is open then it will be above 2K ohms or infinite.

Thus, this is all about an overview of the motor winding theory. From the above information finally, we can conclude that windings are made with copper wires which are wound around a core to make or obtain electromagnetic energy. The wire utilized within the windings should be protected. But in some cases, we can see the windings like bare copper but it’s simply coated with enamel. The most commonly used material for winding is copper. Aluminum can also be used but it should be thicker to hold a similar load securely. The copper winding allows for a tiny sized motor.

These motor windings are very important components within an electrical machine. It includes a set of coils in the slots as well as consistently spaced in the region of the winding’s margin. Here is a question for you, what is cooler motor winding?

Whena motor burns out, do you rewind it or replace it? Back in Issue 3 of Smart Energy User we introduced this important topic, and here andin our next issue we explore some of the key questions in more detail.

Sometimes — for one of the reasonsdiscussed in this article — the obvious best approach is to rewind themotor. If the magnetic core of a failedmotor is undamaged and appropriate procedures are followed, a rewound motorwill retain its original efficiency. Properly repaired, a “standard” efficiency motor will have its original“standard” efficiency, and an energy-efficient (EE) motor will have itsoriginal high efficiency.

On the other hand, those times when amotor has failed are also opportunities to upgrademotor efficiency. Especially if thefailed motor is 10 or more years old — perhaps with unknown efficiency, andpossibly having been improperly rewound in the past — you will want toseriously consider all the options,and look into the economics of replacing it with a new EE motor.

THE PAYBACKISSUE

The more horsepower a motor delivers, andthe more hours per year it runs, the greater the operating cost and the moreimportant the motor’s efficiency turns out to be. Small motors, and motors that are used infrequently or only forshort periods, don’t cost a lot to run even if they are inefficient. But when a large horsepower motor operatesfor thousands of hours per year, the operating cost is substantial. And, that motor’s efficiency can have asignificant effect on the company’s bottom line.

If a standard efficiency motor has failed,you face

adilemma: Should you spend x dollars tohave the motor rewound, and keep the operating cost the same — or potentiallyhigher? Or should you spendsignificantly more than x dollars for a new EE motor, and reduce the operating cost? It is possible to arrive at rational answers to these questions by doingsome simple calculations. For informationon how to do this, see the article in the last issue (Issue 17), Calculating What it Costs to Run a Motor,and the article in our next issue (Issue 19), Easy Comparison of Motor Cost/Payback Options. (If you don’t have copies of these issues,call us.)

STATOR COREDAMAGE

Induction motors employ an armature that rotates within a fixed stator, with a small air gap between thetwo. A typical motor stator is shownbelow.

Typical induction motor stator

Itconsists of a core of stacked, insulated, iron laminations, with windings ofinsulated copper wire