The acceptance criteria depends on test procedure but normally should not be more than +/- 2° celsius. Shaft Condition: Manually rotate the motor shaft to assess its condition. The stator core is usually constructed of iron to reduce load losses. The steel laminations, squirrel cage, and bearings, are all mounted onto the rotor shaft. However, this problem has been mitigated significantly in recent years due to the advancement and application of variable speed frequency drive technology. Light: 1 pound, hand-held. Polarity Test of a Transformer – Circuit Diagram and Working. Field testing & inspection of 3-phase squirrel cage motors - Resource Library. This process is continued until 60% of rated voltage, and several data points are taken. What is a Squirrel Cage Motor and How Does it Work? The other side will have terminals labeled T1, T2 and T3 or Load 1, Load 2 and Load 3.
Block Rotor Test of Induction Motor. The course has a quiz, handbook, and you will receive a certificate when you finish the course. This test can also be used to balance 3 phase motors, as the phase-to-phase resistance of each winding can be compared to see how they differ from one another. Diagnose ground faults, test stator windings, test cables, and induction motor abnormalities and receive results all on one screen within minutes. Motors and Transformers Final Exam Flashcards. Much like a multimeter, a megger has two leads where one connects to ground and the other to specific motor leads. So, the equivalent circuit of this test is shown in the figure below. While induction motors exist in numerous forms, this article focuses on the 3-phase squirrel cage induction motor design because it is by far the most common type of induction motor.
The motor overload operation is caused by the unreasonable configuration of the motor and load. Insulation to ground faults. Types of Motor Controllers and Drives. Did you find this article useful?
The power supply test can be done by checking the voltage being applied to the motor with a multimeter. How to test a squirrel cage motor for furnace. Bearing Vibration test is performed when the rotor running at the no-load condition and the velocity vibration amplitude shall be measured in horizontal, vertical and axial directions. As the supplied voltage is zero, the stator copper loss and core loss become zero. PRECAUTIONS: - TPST switch is kept open initially.
A. direction of the turning force. The insulation resistance test is the next test that must be done to determine the overall health of the motor. The connection diagram of the no-load test of an induction motor is shown in the figure below. This article will go over the basics of motor testing and what types of motor testing are provided. These include: - Wearing protective safety gear: This safety gear may include grounding straps, gloves, and any other relevant protective gear for the environment. Are used as defined in the IEC60034-1 and IEC60034-2. In this test, the rotor is locked and it cannot move. Sources: - - - - - - - - Other Motors Articles. 20-30% of rated current) and the slip is extremely small (in order of 0. Then, the voltage is increased to the 120% of the rated value at the rated motor speed. This curve is illustrated in the below figure. The resistances are measured by the Voltammetric method at ambient temperature. How to test a squirrel cage motor mount. In the case of a wound rotor motor, the stator and rotor resistances are separated by dividing equivalent resistance R01 in the ratio of DC resistance of the stator and rotor windings. Then be sure to check out our Induction Motor Video Course!
Other sets by this creator. This back-current is a function of the motor's poles and slip frequency (if slip is present), and will appear on spectrum analysis graphs as "side-band" peaks around the supply line frequency (60HZ in North America, 50Hz in Europe). Understanding the basics of electric motors can help you understand where the problem may be coming from, while proper diagnostic tools can help you identify and clarify the issue. The induction motor shall run at the rated voltage and frequency, and each bearing temperature is measured periodically. The test involves positively charging the motor conductors and negatively charging the frame for ~10 minutes. The detection method is to use a megohmmeter to test the DC resistance of each winding of the motor, if the resistance is too small, the motor winding is damp; if the resistance is equal to zero, the motor winding is completely grounded. This paper presents a way of exact core losses determination in full-load motor. Hence, for this type of motor, the no-load test is convenient to determine performance parameters. Squirrel cage motor applications. Phase systems are alternating current power supplies that are defined by the number of phases in the power supply. Stator windings are usually manufactured from copper, although other materials are available e. aluminium. The windings receive three-phase AC power, which causes a magnetic field around each of the windings to expand and contract when current is flowing.
While electric motors may be complex, diagnosing them doesn't have to be. The new ALL-TEST PRO 34™ empowers technicians to efficiently and accurately evaluate motors whether they are in the field or on the shop floor – improving motor reliability, increasing technician and asset productivity, and reducing energy consumption. This test has become increasingly difficult to use as a standalone acceptance test because of newer insulation systems but is still useful in conjunction with other tests to verify results. Squirrel Cage Rotor Testing - Resource Library. The ALL-TEST PRO 34™ is extremely portable and easy to operate, and it can assess the health of virtually any squirrel-cage rotor mower <1000V within a 1, 000-foot range. Depending upon the design, a rubber dust seal may sit in this space.
Note: Route feature will only work with Enterprise Software. A previously-broken motor will never run at the same efficiency, even if repaired, so testing can make sure that the motor retains its performance over the maximum value of its useful life. Know in a few minutes what the problem is: connections or cable, electrical or mechanical, coil, internal fault or ground fault. After thermal stabilization (bearing temperatures), the motor is stopped, and hot stator resistances is measured, and temperature rise is calculated based on following parameters: The stator temperature rise level shall be verified based on acceptance criteria addressed in the induction motor routine testing protocol /test procedure. All variable such as current, voltage, power, stator temperature, bearing temperature are measured at the start and also in each 30min based on the test procedure. Hence, the input power at zero voltage and no-load is given by OA and it represents the friction and windage loss. The reading must be taken as quickly as to avoid overheating. When the test facility is not capable of conducting a full load temperature rise test, the test is carried out at reduced power with results extrapolated to rated values.