These cookies track visitors across websites and collect information to provide customized ads. However, this is actually the speed of the magnetic field, called the synchronous speed, which is not always equal to the shaft speed. The required speed can be achieved by adjusting supply frequency of an AC motor. Synchronous motor: Stator has axial slots which consist stator winding wound for a specific number of poles.Generally a salient pole rotor is used on which rotor winding is mounted. Calculate (1) synchronous speed (2) slip of the motor when speed is 720 RPM. 1.32. Example Synchronous Speed of Electric Motor with Two Poles A motor with two poles is supplied with power with frequency 50 Hz (1/s). To reveal the relationship between slot-pole combination and vibration/noise, the electromagnetic force, vibration and noise in PMSM with six combinations are studied. The basic formula for formula for Synchronous Speed of Induction Machine is: . The rated speed of the motor is mentioned in RPM. Necessary cookies are absolutely essential for the website to function properly. Already a member? A stator is a stationary part (Unmovable) of a synchronous machine. SM-5: Results of application and removal (after the critical clearing time) of a three-phase short circuit The cookies is used to store the user consent for the cookies in the category "Necessary". Slip = Synchronous Speed Actual Speed Using the example above for synchronous speed of a motor with four poles operating at 60 hertz, the value was calculated to be 1800 RPM. Its stator winding is excited by an AC source. In order to find out the synchronous speed roundup the values mentioned on the nameplate to the nearest value in the table below: Speed at 50Hz. Synchronous Motor. 3 How do you calculate synchronous speed? This cookie is set by GDPR Cookie Consent plugin. 12 poles or 6 pairs of poles = 500 RPM. 2 What is the rotational speed of a three phase motor with 6 number of poles and frequency of 60 Hz? Analytical cookies are used to understand how visitors interact with the website. RPM = shaft rotation speed or revolutions per minute. It is common to express the slip as the ratio between the shaft rotation speed and the synchronous magnetic field speed. The actual running speed is the synchronous speed minus the slip speed. The cookies is used to store the user consent for the cookies in the category "Necessary". Because the magnetic poles appear in pairs, the motor can be divided into 2, 4, 6 and 8 "poles. The most common application of synchronous motor is the things that require a constant speed because the power frequency is controlled precisely for the short and long term-for example, Digital and Analog clocks, tape recorders, phonograph turntables, etc. You also have the option to opt-out of these cookies. Motor speed = 60f/p that is 60 times motor frequency divided by motor pole logarithm. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. Where, f = supply frequency and p = number of poles. Note - an induction motor will never reach its . Synchronous motor requires an additional DC power source to initially rotate the rotor near to the synchronous speed. Can a induction motor reach its synchronous speed? How many Poles are there in a 60 Hz power supply? The speed of the induction motor is inversely proportional to the speed; if the load is increased, the speed of the induction motor decreases. However, you may visit "Cookie Settings" to provide a controlled consent. Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a parts function at the center of their design considerations. The RPM is calculated by multiplying the frequency times 60 and dividing by the number of pairs of poles. For a synchronous motor to work, the rotor shaft turns at synchronous speed and the magnetic field produced by the field winding couples with stator . Synchronous motor is mainly consisting of two parts one is Rotor and other is Stator. The actual running speed is the synchronous speed minus the slip speed. A synchronous motor is based on the principle of magnetic interlocking. 60Hz is the most common frequency in the US. Similarly, frequency is the number of positive & negative cycles of input AC supply per second. For example, it is used in watches. Due to that the generator may loss its synchronism and Pole slipping occurs. The poles are laminated by silicon steel and carry the field winding, and the pole faces are generally provided with slots (Provide support) for squirrel-cage winding. A synchronous motor refers to an AC motor that runs at synchronous speed. An AC motor refers to a motor that takes AC supply as an input and converts it to rotational motion (Conversion from electrical energy to mechanical energy). The rotor of a synchronous motor is made up of permanent magnet coils excited by a dc supply. If the magnetic poles are attracted and interlocked the rotor continues to rotate with synchronous speed. . In an induction motor, a changing magnetic field induces currents in the rotor, so the rotor will always rotate more slowly than the synchronous speed of the magnetic field in the stator. In order to vary the speed of a synchronous motor, the supply frequency must be varied. A method of protecting a synchronous machine ( 10 ) connected to an electricity network ( 12 ) against pole-slip comprises the steps of continuously monitoring a power transfer angle () between an electromotive force (EMF) of the machine and a reference voltage V ref . The synchronous speed for an electric induction motor is determined by. Which is the correct formula for synchronous speed? Solution (1) Synchronous speed = 120 = 120 50 8 = 750 R P M = (2) Slip of the motor, when Nr = 720 RPM = = 750 720 750 = 0.04 p e r u n i t Accordingly, the more poles, the slower the synchronous motor turns. 10 poles or 5 pairs of poles = 600 RPM. Number Of Poles. What is the slip frequency of an induction motor? The starting of a synchronous motor is the same as an induction motor initially excited by 3 phase AC supply given to the stator. By joining you are opting in to receive e-mail. If you need to purchase motors or learn more, please feel free to, 2019 Nantong Kinchi Motor Co.,Ltd All Rights Reserved. Abstract and Figures The paper presents a new method of pole slipping protection which eliminates the need for complicated calculations of setting, thus greatly simplifies the setting process.. Frequency. 16 poles or 8 pairs of poles = 375 RPM. These cookies will be stored in your browser only with your consent. The stator core is made up of steel lamination sheets which helps to reduce the eddy current losses. An induction motor always runs at a speed less than synchronous speed. Occasionally, if the overload is momentary, the motor will "slip-a-pole" and resynchronize. The synchronous motor needs a separate DC source for rotor excitations, while the other motor doesn't need any separate excitation. The cookie is set by GDPR cookie consent to record the user consent for the cookies in the category "Functional". Join your peers on the Internet's largest technical engineering professional community.It's easy to join and it's free. This website uses cookies to improve your experience while you navigate through the website. Thanks. 60Hz is the most common frequency in the US. It is more expensive to build a slower motor, given equal horsepower. In a synchronous generator, a DC current is applied to the rotor winding, which produces a rotor magnetic field. The 3600 rpm corresponds to 60 revolutions per second. The same formula used to calculate the speed of the induction motor is used to determine the speed of this type of motor. By clicking Accept All, you consent to the use of ALL the cookies. The synchronous motor uses a stator just like an induction motor to generate a rotating magnetic field (RMF). Now while starting of the motor on synchronous mode we are facing problem following issue; 1) While initial starting as a asynchronous mode - motor runs smoothly. Our engineering expertise, and understanding of the complete process, complimented by our . This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. The percentage slip in case of a synchronous motor is (a) 1% (b) 100% (c) 0.5% (d) zero Ans: d. 32. We have received your request and will respond promptly. The construction of a non-salient pole rotor is cylindrical, which contains parallel slots to place rotor windings. Click Here to join Eng-Tips and talk with other members! For a 50 Hz three phase supply: 2 poles or 1 pair of poles = 3,000 RPM (minus the slip speed = about 2,750 RPM or 6 -7% n). Reply. When a larger quantity of poles is required, salient pole rotors are the best choice to be used. Synchronous speed in an electric motor is the speed that is produced by the traveling magnetic filed wave as it rotates around the stator magnetic circuit. Outside of this line, pole slipping becomes a real possibility in the event of a system fault. It has varying speeds. But opting out of some of these cookies may affect your browsing experience. It can be operated with a leading and lagging power factor by just changing its excitation. Because the magnetic poles appear in pairs, the motor can be divided into 2, 4, 6 and 8 "poles. downloads. . A synchronous motor uses cylindrical and round rotors for 6 pole applications. To create a six pole motor use six coils per phase that creates three north poles and three south poles and so on. Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. According to the formula, it is not difficult to see that the more the series, the lower the rotational speed, the fewer the poles, and the higher the rotational speed. *Eng-Tips's functionality depends on members receiving e-mail. In my ongoing project, we have GE make Compressor Synchronous motor of 17.5MW @0.9pf, 11kV, 1500rpm, 4 Pole, DOl Starting Type. What is the rotational speed of a three phase motor with 6 number of poles and frequency of 60 Hz? You also have the option to opt-out of these cookies. A synchronous motor refers to an AC motor that runs at synchronous speed. The synchronous speed of an AC motor is determined by the frequency of the source and the number of poles. Amol . First, it is a highly efficient means of converting AC energy to work. PMSM with other slot-pole combinations are described by such analogy. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. What is synchronous speed when F 60hz P 6? What is the synchronous speed of a 6 pole motor supplied at 60 Hz? This rotating magnetic field induces a three-phase set of voltages within the stator windings of the generator. The cookie is used to store the user consent for the cookies in the category "Other. October 25, 2020 by Electrical4U. The synchronous speed of a motor is equal to 120*f/p where f = the system frequency in Hz and p is equal to the number of poles in the motor. The RPM of the motor rotor, i.e. Already a Member? RPM = shaft rotation speed or revolutions per minute. A dc generator can be converted to a D.C. Motor and used to accelerate the synchronous motor rotor This article discusses an overview of the asynchronous motor like its . the power supply frequency, and; the number of poles in the motor winding. Therefore, value of the slip is 1. The theory of these motors has been developed on the basis of synchronous reactance, which takes care of leakage reactance and armature reaction.A salient pole machine, which has a non-uniform air gap, is described by direct and quadrature axis reactances. The synchronous speed of a motor is equal to 120*f/p where f = the system frequency in Hz and p is equal to the number of poles in the motor. Synchronous motor consists of two Primary part; Stator and Rotor. A generator is most susceptible to this problem when it has a low excitation, as this produces a weak magnetic field. The air gap in the salient pole rotor is non-uniform, and the poles are projecting in outward direction to the rotor surface. Because of the large torques that occur on the turbine-generator during pole slipping, synchronous machines in the United States are designed with protection to prevent its occurance. In the inventive method, measured signals of current and voltage of the synchronous machine (2) and assumed constant parameters are the . the synchronous speed N, is: N = 120f/P = 60 f/P. The winding of the starter is 3 phase winding which is excited by the 3 phase AC supply. Login. A 3-phase source is attached to the armature winding, and the armature develops a rotating magnetic field that rotates with a synchronous speed of 120f/P. Synchronous motor work. It is also known as an asynchronous motor. When the rotor's speed, as well as the speed of the magnetic field within the stator, varies, then these motors are called asynchronous motors. The number of poles of the motor is the number of magnetic poles in each phase of the motor, and the number of poles corresponds to the rotational speed. Rather, the speed of the wave is dependent upon the properties of the medium such as the tension of the rope. This cookie is set by GDPR Cookie Consent plugin. 4-6 poles synchronous motors - FACT SHEET. The variation within the speed can be called as the slip. This series of motors is rated at 6000V . The stator comprises a cast iron core which is known as a yoke provide strength to the machine. 1 What is the synchronous speed of a 6-pole motor supplied at 60Hz? For the convenience of description, PMSM with 2 poles/12 slots and 2 winding layers is abbreviated as P2S12C2. The speed of a synchronous motor is dependent on the frequency of the power source and the number of poles the stator has. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. The slots are connected in series to the slip rings, which are excited by the DC source supply. 6 Can a induction motor reach its synchronous speed? A synchronous motor works on the principle that the poles of a DC excited rotor will lock onto the poles of opposite polarity, which are created by the three phase stator winding. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. What is the synchronous speed of a 6-pole motor? 4 poles or 2 pairs of poles = 1,500 RPM. These cookies will be stored in your browser only with your consent. But during some extreme fault condition such as heavy line fault, lightning impulse, switching transient etc. Synchronous motors run at synchronous speed. The magnitude of the variable magnitic rotating field pole is controlled by excitition current. A 4 pole, 60 Hz Induction Motor Has a Slip of 5%. It is usually expressed as a fraction or percentage of the synchronous speed. The data convincingly show that wave frequency does not affect wave speed. The RPM is calculated by multiplying the frequency times 60 and dividing by the number of pairs of poles. It is the notches that let. An AC (Alternating Current) induction motor consists of a stator and a rotor and the interaction of the currents flowing in the rotor bars and the rotating magnetic field in the stator generates the torque that turns the motor. The rotating magnetic field which is produced in the stator will generate flux in the rotor which will make the rotor rotate. The 8- to 40-pole synchronous motor high-pressure mine synchronous motor is suitable for working in an indoor environment where the altitude does not exceed 1000 m, the temperature of the cooling medium does not exceed 40 degrees, and there is little dust, no corrosive gas such as steam, acid or alkali. The subject of the invention is a method for protecting a synchronous machine (2) against damage caused by pole slipping, applicable during the operation of the synchronous machine in a power generating unit or a drive unit (1) in an electric power network. Where f is the frequency of the ac supply in Hz, P is the number of poles (per phase), and p is pair number of poles per phase. What is the synchronous speed of a 6-pole motor? After entering the required data from the nameplate, click on the "Calculate" button to find out the number of poles.