These losses are further classified as- 1. Before troubleshooting the 3 phase induction motor, we must have to know about the 3 phase induction motor, star delta starter and itâs connection diagram. No responsible discussion of electrical equipment maintenance would be complete without first covering the need to maintain a safe working environment. High cycle operation of a motor also adds heat to the motor. Motors are designed to run during normal operation within the ratings on the motor nameplate. This troubleshooting guide can also be applied to other types of three phase induction motors: Load imbalance — Load imbalance is an additional cause of motor vibration. 78681. ), Load type (constant torque, variable torque, high inertia), Starting method (across the line, VFD etc. three-phase motor winding formula,3 phase motor winding diagram pdf Firma size coil size setting, Full information by Motor Coil Winding Data. Check with your pump manufacturer to ensure the pump is operating within the design capabilities. Metallurgical ContentMotor SwitchesAir MotorsFractional HP and General Purpose MotorsSynchronous Motors Motor Switches Motor starting switches have been developed for a wide variation of load requirements, and special switches are available for operation in damp or dust laden atmospheres with high efficiency. In the April 2006 issue, “Repair or replace? (More advanced testing requires specialized tools. Typical tools used for troubleshooting motor operation problems include an ac voltmeter, ac clamp-on ammeter, ohmmeter and meg-ohmmeter. The motor may also be sized incorrectly for the load requirements. If someone works with AC 3-phase motors, then it is important to know how to connect these motors in Star and Delta connection, and how to detect an electrical problem. 2 contactors burned out in one day but nothing wrong with motor. Check out your facility’s power system and resolve the supply problem. The voltage measurements from phase-to-phase should be very close to the same readings. It should be approximately the same. 2)Check the unbalance voltage and inform to Electricity Board people. Improper ventilation. Numerical Problems Induction Motors . One dynamometer with torque controller . These rules may include personal protection equipment, electrical safety precautions, lock-out/ tag-out procedures and any other established safety requirements and procedures when working around electricity. b)1) Check loose connection. A good motor should read less than 0.5 ohms. The ratings refer to the speed range capability of the motor below the nameplate RPM rating. Find the percentage slip and number of poles of the induction motor. If your motor is not generating the required torque for your operation, first check motor voltages as described previously. The induction motor sound is abnormal. After verifying that the motor voltage and motor resistance are okay, use an ac ammeter to check the motor current. Brush friction losses. So letâs take it one by one: Here we are giving you only overview on 3 phases induction motor. Steven Seiden, Leighton Johnson, Dr. Tony Barber, Djenana Campara, By Timothy H. Tiebert, Senior Electrical Engineer, Kaman Industrial Technologies, Pandemic transforms the system integration industry, Applied Control Engineering Inc., is System Integrator of the Year, 2021, The need for robotic offline programming in a COVID-19 world, Cybersecurity and the rise of IT-enabled OT systems, How collaborative robots’ role is growing on the plant floor, Direct drive vs. geared rotary servomotor: A quantification of design advantage: Part 1. MAINTENANCE AND TROUBLESHOOTING: The very first thing that you should do before starting any type of maintenance on a motor is a visual inspection, a lot of times the trouble can be found just by looking, because if the problem is that bad then it should be very obvious by observation. Any value greater 0.5 ohms indicate trouble with the motor. If there are no resistance problems found using the ohmmeter use the meg-ohmmeter to test the same series of test measurements as described with the ohmmeter. This will decrease the ability of the motor fan to remove the heat produced by the motor. Single phasing (three phase only) Check the current at all phases. These tools are used to measure the motor voltage, current and resistance. Electrical stalling, especially in a 3 phase induction motor, typically is result of a single phase or missing phase condition. At the line side of the motor control device (power supply side of a motor starter), check and record the voltage phase-to-phase and phase-to-ground for each combination. Voltage imbalance is a common and damaging source of overheating. Squirrel cage and induction-type refer to the construction and operation of the rotor. Open the motor connection box, disconnect the motor connections and check the motor windings using the ohmmeter. If the voltage is good, go to Step 2. A low voltage situation does not provide the necessary power to allow the motor to achieve the expected torque rating. Take time when handling a motor failure situation to carefully diagnose the situation and gain a complete understanding of the source (or sources) of the problem. The following steps should assist you in discovering and fixing vibration problems: Misalignment and unbalanced loads — Misalignment between the motor shaft and the load shaft causes unnecessary vibration. If the resistance on the motor is low phase-to-ground, there is a short in the motor, and it must be replaced. b) Unbalance incoming 3 Phase voltage to motor. THREE PHASE INDUCTION MOTORS TECO-Westinghouse Motor Company 5100 North IH-35 Round Rock, Tx. If the phase-to-phase resistance is high, there may be an open winding in the motor, open wire to the motor or a bad connection in the motor connection box. Check external cooling fan to be sure air is moving properly through the cooling channels. Be sure to take all necessary precautions to protect yourself or your employees from harm. Motor operational problems are a common cause of downtime and maintenance headaches. Generally, modern electric motors provide long trouble-free service if care is taken in the initial application and routine maintenance of the motor. The resistance from phase-to-ground should be very high for each combination of measurements. Follow the steps below to check for the most common problems for three-phase motors. Power Supply Test For single phase motors, the expected voltage is about 230V or 208V depending whether you are using the UK or America voltage system. Typical motor characteristics may include a motor hum or a motor with very little torque when turning. The three phase supply current produces an electromagnetic field in the stator winding which leads to generate the torque in the rotor winding of three phase induction motor having magnetic field. ... understanding of electrical principles and the efficient use of test equipment is important to the electrician in this phase of troubleshooting. Check and record phase-to-phase and phase-to-ground resistances. Initial Data . If the amperage reading for each phase is larger than the full load nameplate reading, the motor is overloaded. Mechanical stalling is typically the result of the driven device being unable to move. Since youâll be testing the motor only, itâs best to first remove the connecti⦠In two-phase operation, there is a buzz sound. Determine if the problem is the motor or the feed wires. Before you begin, assemble some basic diagnostic equipment for the job. 2 << INSTRUCTIONS FOR THREE-PHASE INDUCTION MOTORS This equipment contains hazardous voltages. Replace the bad wires or reconnect and insulate the motor connections in the motor connection box to eliminate the short circuit. Make the right decision on motors” discussed the repair or replace decision. (Telecommunication Engineering), Southwest Jiaotong University, China, 2005 Check the load for problems such as a jammed load, too much material or bearing failure. 4) Motors runs and then stops a) Check loose connection to the line of fuses and starter in the motor Terminals. Starting Current, sometimes abbreviated as I start in electrical engineering, is a measure or rating of how much current required for a single or three phase AC motor to ⦠This is why motors are designed to dissipate heat during normal operation by use of their external surfaces and typically a cooling fan. HUÉnA½÷WÔ)ÂRhº{z=ñ$Æ While a single-phase motor is normally resilient and can operate unhindered for decades, there will come a time when it will break down and cause problems. Measure and record the amp reading for each phase (T1, T2 and T3). To determine if a voltage imbalance exists, first check the supply voltage to the motor control device when the motor is not running. ö eû»jI%Ö`'¡N>BQ^"×îé¦@ ôáîÀCÌÏSî|. The amp reading for each phase should be similar. Appendix 47 14.1 HLA7 Horizontal-type Motor Construction 47 If the amp readings for each phase are very different, this may indicate a problem with the voltage or a failure in a motor winding or connection. Cavitation is present when the pump is running outside its capabilities. If the motor resistance to ground is high on the motor leads, check the feed wires. Those are described below. The table below gives the commonly encountered problems in 3 phase squirrel cage induction motors, cause of problems and what remedy to apply to bring the motor back to production. Accumulation of dust and dirt on a motor insulates the motor. Then check the motor voltage and resistance readings as described earlier. If the motor is overheating, check the area around the motor for high ambient temperature conditions. With a multimeter, measure the resistance between motor frame (body) and earth. Correct motor selection and application criteria include: Mounting requirements (Foot mount, C-Face mount, etc. One 208 Volt, 0.75 HP, 3-phase induction motor . Check the motor starter leads for a phase-to-phase or a phase-to-ground short. Constant losses are those losses which are considered to remain constant over normal working range of induction motor. The nameplate has a full-load amp rating. Motor fails to start or not accelerate (Faults in starting supply circuit) Motor Switch ON but does not start 1.Blowing of fuse/tripping of MCB 2.Terminal voltage too low 3.Defective starting mechanism 4.Protection devices has been tripped 5.The motor controller will not operate 6.Open circuit in supply cable. If not, check supply circuitry, breakers and condition of the motor's power cord. The motor is not designed to remove the heat that is generated at levels above the full load amp rating except for starting and intermittent load surges. When running a motor with a variable frequency drive, motors have a speed range rating at which it effectively removes the heat at the rated load. larger motors. 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