There is an extensive wikipedia article on induction motors, so ill try to keep this page simple. Spare parts, installation and maintenance of ac electric induction motors. Manual shall not be considered or inferred to be the official position. Differentiate between the various types of generating electric power stations. Introduction to ac motors ac motors electronics textbook. The cool side is usually located within your furnace. However, should the motor require service, this manual includes a section that assists the. This type of motor operates like a twophase ac motor and is used to drive actuators. Standard for an electrical preventive maintenance epm. Once there is a short in the windings it is time to. Types of ac induction motor rotors there are twotypes of rotor windings. If a company wanted to have reliable production, it should stick with known, proven. Interpret this ac motor control circuit diagram, explaining the meaning of each symbol.
It consists of a group of individual electromagnets arranged in such a way that they form a hollow cylinder, with one pole of. Machine stopped and partially dismantled end covers removed. Open vent holes and check for a continuous stream of air from the motor. It is logical that the least expensive, lowest maintenance type motor should be used most often. An ac motor is an electric motor driven by an alternating current ac. It has brushes like a dc motor, but will operate on ac or dc. Testing and commissioning procedure for electric motors eep. Your brook crompton motor is designed for long life, and. During the installation and operation of motors in heavy industrial applications there is a danger of live electrical parts and rotating parts. Classification of electric motors electrical knowhow.
Explain how this motor can be operated as either a synchronous motor or a plain induction motor. Vfd fundamentals copyright 2003 kilowatt classroom, llc. It was the wicked and insane genius nikola tesla who invented them. The main components of an ac induction motor are the rotor and the stator. The specified repair, maintenance, and overhaul must be carried out regularly by trained service. The motor should be installed in a location compatible with the motor enclosure and specific ambient.
Ac, or alternating current, is the electricity that flows back and forth. The ac motor commonly consists of two basic parts, an outside stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft producing a second rotating magnetic field. But the shaded poles dont provide very much starting torque. Difference between dc and ac motors difference between. Ensure that the connectors are properly used and installed in accordance with manufacturers specifications. Besides this manual, be sure to read other manuals and all danger warning caution name plates. Alternating current motors or ac motors are built on the principle that nikola tesla discovered in the late 19th century. Motor vibration shall be measured in a triaxial direction, i. Provided that the motor rotates easily, each pulse will cause the rotor to turn by a few degrees. Other unlisted or specialized ac motor construction.
Spare parts, installation and maintenance of ac motors mammoet. What is common to all the members of this family is that the basic physical process involved in their operation is the conversion of electromagnetic energy. Reveal answer the difference between the speed of the rotating magnetic field fixed by line power frequency and the speed of the rotor is called slip speed. The ac induction motor is well suited to applications requiring constant speed operation. Over 30 years ago, ac drives were considered new technology. The stator is in the stationary electrical component. I previously covered how dc motors work, but ac induction motors are actually much more useful for homemade machines such as bandsaws. If the copper ring is moved away from the end of the permanent magnet, the direction of force will reverse and become attractive rather than repulsive followup question. This 3 phase motor is also called as an asynchronous motor. An ac controller can also be referred to as a variable frequency drive, adjustable speed drive, frequency converter, etc. Explain what slip speed is for an ac induction motor, and why there must be such as thing as slip in order for an induction motor to generate torque. Ac asynchronous motor sections mvhv voltage ac synchronous motor sections dc motor sections common variance in construction or major accessories stator frame with wound poles stator either wound or permanent magnets yoke, adjustable stator poles no field winding on pm stators horizontal or vertical mounting either wound or squirrel cage rotors. Frame or bracket vents may be clogged with dirt and prevent proper ventilation of motor. An electric motor is a device which converts electrical energy.
Testing of induction motor december 30, 2018 february 24, 2012 by electrical4u demand of energy is growing day by day and along with it cost of energy rising abruptly, so now it is necessary that the health of large motors which consumes maximum power should be taken care off. Both direct current dc and alternating current ac motor types are. It should be noted that the scope of motor testing depends upon the motor type and size, this being indicated on the inspection forms. Instead, the commutation of the windings of a bdc motor is done mechanically. If the motor then operates smoothly, look for the source of noise or vibration in the driven equipment. The induction motor is made up of the stator, or stationary windings, and the rotor. Before we discuss these modifications, here it is essential to discuss what is the need and where do we need to do modifications. Does the issue follow the motor lead or stay in the same phase. Ac induction motors are one of the most common types of motors used in a variety of applications due to the fact that they run off of ac voltage which is readily available at every outlet.
If the selected abc series is sized to deliver 200% of motor rated current, consider each brake cycle to be 2. Mostafa elshahed objectives learn a brief history of the electrical power systems construction. Jan 06, 2019 ac series motors are also known as the modified dc series motor as their construction is very similar to that of the dc series motor. In order to reduce the chance of personal injury andor property damage, carefully observe the instructions that follow. Synchronous motors are so named because they run synchronously with whatever the frequency of the source is. To some, motor speed control is somewhat of a mystical science, a science that causes motors and machines to sometimes operate in unexpected ways. The threephase ac induction motor is a rotating electric machine that is designed to operate on a threephase supply. Put neither finger nor the thing in the opening of the electric motor. The motor speed is fixed and doesnt change with changes to the load or voltage. This motor was new but after some days it just stops moving and we checked from. Test interphase resistance by disconnecting the leads from each terminal. All ac motors have the same basic components, a stator and rotor. The stator is the stationary coils in the motor where the current is produced to create the. It is logical that the least expensive, lowest maintenance type.
Spare parts, installation and maintenance of ac motors. Condition assessment and life expectancy with 85% confidence 2. The specifications included in this part are only those necessary for the inspection and overhaul procedures which follow. Ac motor, main drive controller assembly, and driveoperator interface 210211. By using an inverter type ac drive, the speed of a conventional ac motor can be varied through a wide speed range from zero through. View and download ford ranger maintaince and repair manual online.
Most central air conditioning systems include a hot side, outside your home, and a cool side, inside your home. Remove the old grease when overhauling the machines. List and describe the more commonly used equipment in an electric substation. A variablefrequency drive is a device used in a drive system consisting of the following three main subsystems. An ac controller sometimes reffered to as a driver is known as the device that controls the speed of the ac motor. Ac motors, controllers, and variable frequency drives. If either is unknown, the correct sequence can be determined in the following. Induction motor theory jerry bednarczyk, pe course content introduction the ac induction motor is well suited to applications requiring constant speed operation. The theory used in the work was collected by studying literature on how electrical motors work, and by simplifying the. The service manual of general motors powertrain is intended for use by professional, qualified technicians.
The ac induction motor is the most used electrical motor in industrial applications worldwide. Motortronics abc series electronic motor brake user manual. The ac motor receives power, which is ultimately converted by the ac controller into an adjustable. This video explains how ac motors work, using a simplified example which uses a permanent magnet as the rotor. Universal universal motors can operate at approximately the same speed and output on either dc or singlephase ac power. On the other hand ac or alternating current electric motors are used in a completely different process drawing upon the kind of ac motor being used. The ac electric motor used in a vfd system is usually a threephase induction motor. The brushless dc motor, actually an ac motor, is replacing the conventional brushed dc motor in many applications. The inner part that moves, called the rotor has no electrical connection to the surrounding stator which does not move. Powerflex 70 adjustable frequency ac drive this document explains the 5 basic steps to install and perform a basic startup of the powerflex 70 ac drive.
In general, the induction motor is cheaper and easier to maintain compared to other alternatives. Figure 81 shows the motor output torque as a function of shaft speed with full rated voltage applied to the motor. Ac motor basic stator and rotor operation diagrams. Standard for an electrical preventive maintenance epm program page 210 andor connectors are used together, examine connections for signs of galvanic action. Cleaning of stator housing varnishing of stator winding heating in oven replacement of bearing testing if required ac motor overhauling overhaul it is. An ac motor of this type may be part of a pump or fan or connected to some other form of mechanical equipment such as a winder, conveyor, or mixer. To show the performance of a motor when connected to a load, a typical speedtorquecharacteristic for a fan is plotted along with the motor speedtorque characteristic in figure 82. This standard specification describes the requirements for the contractor to overhaul ashore in a suitable repair facility an alternating current ac induction or. Oct 06, 2011 the other type of ac motor is a synchronous motor.
Ac motors,motor control and motor protection bill brown, p. Standard for an electrical preventive maintenance epm program. Ac motors work using the interaction of the induced magnetic fields in their two main components. Horizontal squirrel cage mediumvoltage induction motor. Other motors that are included are 1phase induction motors, permanent synchronous motors and synchronous reluctance motors. Because they convert electrical energy to mechanical energy, they are the interface between the electrical and mechanical systems of a facility. Ford ranger maintaince and repair manual pdf download. This standard specification describes the requirements for the contractor to overhaul ashore in a suitable repair facility an alternating current ac induction or synchronous motor removed from a coast guard vessel. A human interface module him is required to perform the basic startup routine that is covered in this manual. Ac series motors are also known as the modified dc series motor as their construction is very similar to that of the dc series motor. If ac motors are not ideal for your application, you may consider brushless dc, brush dc, servo, or stepper motors, and their compatible driverscontrollers. These devices are connected in series with the motor conductors.
If output voltages are balanced, then direct attention to motor. The rotor magnetic field may be produced by permanent magnets, reluctance. These motors are primarily used where the requirement is precise and constant speed. The hot side generally consists of a condensing coil, a compressor and a fan. Roll motor leads be particularly concerned about reversing the motor. The principle of an ac motor is that electric current is applied to electromagnets, creating a rotating magnetic field to convert electrical energy to rotation mechanical energy. Basically, an ac motor is a type of motor that is operated by an alternating current. Dec 30, 2018 testing of induction motor december 30, 2018 february 24, 2012 by electrical4u demand of energy is growing day by day and along with it cost of energy rising abruptly, so now it is necessary that the health of large motors which consumes maximum power should be taken care off. Condition assessment and life expectancy with 80% confidence 2. Cables may also be purchased from anaheim automation. The figure above shows the family tree of the ac motors described in this chapter.
Jun 01, 2017 in this video, you will know how to open a 25kw electrical motor and find out what is the problem with this motor. Place one megger probe to the any mounting bolt on the breaker box to test for grounding continuity, then touch the other probe to a motor terminal. In fact, the torque produced by a stalled shaded pole motor is considerably less than when its running near full speed. Ac motor cables can be custom made with the supplied ac motor connector to fit given specifications.
Motor theory a step motor is a constant output power transducer, where power is defined as torque multiplied by speed. Describe how a squirrel cage motor is built, and classify it as either an induction motor or a synchronous motor. Ac motor manufacturers recommend that each braking cycle over 100% fla be considered as an additional starting cycle when calculating the starts perhour ratings for the selected motor. Apply an antioxidant compound to all aluminumto copper connections. What is common to all the members of this family is that the basic physical process involved in their operation is the conversion of electromagnetic energy to mechanical energy, and vice versa. And, the stepper motor, a digital version of the motor, is driven by alternating current square waves, again, generated by solidstate circuitry. L1 l2 run m1 to 3phase motor power source m1 ol ol. Singlephase induction motor threephase induction motor singlephase induction motor there are probably more singlephase ac induction motors in use today than the total of all the other types put together. Over time electric motors may burn out as heat destroys insulation materials in the windings.
How to test a threephase motor with a megger hunker. Universal motors are also known as an ac dc motors. It shows how a 3phase ac motor works with a rotating magnetic field and a permanent magnet rotor, making it a synchronous ac motor. The squirrel cage induction motor was designed for an extended service life under very demanding conditions. Some types of singlephase motors or synchronous motors can be advantageous in some situations, but. Motor speed relationship the synchronous speed of an ac motor is the speed of the rotating magnetic field set up by the stator winding synchronous speed rpm 120 x frequency divided by the number of poles. This means motor torque is the inverse of motor speed. The above diagram shows the configuration of stator winding. If the vibration stops, look for an electrical unbalance. In this video, you will know how to open a 25kw electrical motor and find out what is the problem with this motor. Dc or direct current motors work in particular situations whereby the speed of the motor needs to be externally controlled.
Ac motor, main drive controller assembly, and driveoperator interface 210211 ac motor. A segmented copper sleeve, called a commutator, resides on the axle of a bdc motor. A special type of overcurrent protection device used commonly in motor control circuits is the overload heater. These devices are connected in series with the motor conductors, and heat up slightly under normal current conditions. For example, the speed of a 4 pole motor operating at 60 hz would be. Drop motor leads and verify output voltage phasetophase. The principle of operation of this motor is based on. A synchronous motor is often used where the exact speed of a motor must be maintained. Lecture 6 three phase induction motors cairo university. This will produce a counterclockwise rotating field, reversing the motor direction.