ö eû»jI%Ö`'¡N>BQ^"×îé¦@ ôáîÀCÌÏSî|. Motor operational problems are a common cause of downtime and maintenance headaches. There are three basic types of small induction motors: split-phase single-phase, shaded-pole single-phase, and polyphase. Aninduction motor induces a current in its rotor so that a magneticforcecan existon rotor conductors A magnetic force acts on rotor conductors which, eventually, turns the rotor F (irotor Bstator)Lconductor For a threeâphase AC induction motor, the rotating magnetic field must rotate faster than Typical motor torque curves indicate a constant motor horsepower output and a variable torque operation above base speed. Be sure to take all necessary precautions to protect yourself or your employees from harm. Before you begin, assemble some basic diagnostic equipment for the job. A three phase, 12 pole, salient pole alternator is coupled to a diesel engine running at 500 rpm. If the resistance on the motor is low phase-to-ground, there is a short in the motor, and it must be replaced. Make the right decision on motors” discussed the repair or replace decision. (More advanced testing requires specialized tools. Generally, modern electric motors provide long trouble-free service if care is taken in the initial application and routine maintenance of the motor. Pump cavitation — Pump cavitation is a common cause of excessive pump vibration which may in turn damage the motor. Appendix 47 14.1 HLA7 Horizontal-type Motor Construction 47 The voltage measurements from phase-to-phase should be very close to the same readings. 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. 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. Proper application and preventive maintenance practices can provide reliable production uptime. Heat can be transferred to the motor through the mechanical connection to a hot load. One dynamometer with torque controller . Motors are designed for running near their nameplate RPM and may run above or below this rating depending on the manufacturer’s specifications. 3 phase induction motor have 3 winding; assume U, V and W. Good troubleshooting skills help to identify the root cause of motor problems and avoid their recurrence. This could include a head pressure that’s too low, an impeller that’s too large, a pump running too fast or a discharge pressure that’s too low. It’s no secret that motors produce heat as a byproduct of their operation. For this example, refer to the motor equivalent circuit and calculations described above. Measure and record the amp reading for each phase (T1, T2 and T3). When a motor starts, higher current than the full load rating is typically required to begin motor rotation and bring the motor up to speed. Find the percentage slip and number of poles of the induction motor. Unbalanced voltage (three phase only) Check the voltage at all phases. Proper motor maintenance includes regular bearing greasing (do not over-grease), vibration monitoring, cleaning and conditioning monitoring. One of the most common sources of motor operating problems is overheating. motor is a hi low 3 phase motor on a air compressor. So letâs take it one by one: Here we are giving you only overview on 3 phases induction motor. Affix the ac ammeter clamp around one of the motor wires. Check and record phase-to-phase and phase-to-ground resistances. This will decrease the ability of the motor fan to remove the heat produced by the motor. 78681. Check with your pump manufacturer to ensure the pump is operating within the design capabilities. ... Site and environment for motor installation 3.1.1 ... 3.2.3 The foundation of vertical induction motors: (Also the foundation of pump) (a) Foundation of motor/pump must be rigid and secure to provide adequate support. The motor may also be sized incorrectly for the load requirements. b) Unbalance incoming 3 Phase voltage to motor. Typical motor characteristics may include a motor hum or a motor with very little torque when turning. The ratings refer to the speed range capability of the motor below the nameplate RPM rating. 2 contactors burned out in one day but nothing wrong with motor. One Phase Sequence Indicator . Record all nameplate information for the induction motor. If the motor starter leads are clear, move on to the motor. Open the motor connection box, disconnect the motor connections and check the motor windings using the ohmmeter. 2 << INSTRUCTIONS FOR THREE-PHASE INDUCTION MOTORS This equipment contains hazardous voltages. 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. Since youâll be testing the motor only, itâs best to first remove the connecti⦠The amp reading for each phase should be similar. Alternatives for removing the heat from a motor include a constant velocity blower fan, ducting outside air to the motor and the use of a heat exchanger. 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. Constant losses are those losses which are considered to remain constant over normal working range of induction motor. If the motor takes a long time to reach the nameplate RPM or has little torque check for the following: Low voltage — A basic cause of a poor performing motor is low voltage. Using the ohmmeter, check the resistance of the motor leads at the control equipment. 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. Motors require cooling to remove heat generated during operation. Please explain to me if I must really put a contactor on my 3 phase motor. Another possibility is that the motor may be running too slow. This rating should not be exceeded during normal operation, however occasional and brief occurrences are typically not a problem. 1. resistance values chart also covered in this chart. 2. Mechanical stalling is typically the result of the driven device being unable to move. If the phase-to-ground resistance is low, disconnect the motor at the motor connection box and check the motor leads. Excessive motor vibration is usually a sign of either motor or load problems and can lead to premature failure of the motor and the load. When equipment in your plant malfunctions, you need to isolate the trouble quickly. Load imbalance — Load imbalance is an additional cause of motor vibration. If either of these two problems exists, check the motor lead wiring. Death, ... 13. Electrical stalling, especially in a 3 phase induction motor, typically is result of a single phase or missing phase condition. A low voltage situation does not provide the necessary power to allow the motor to achieve the expected torque rating. 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. 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. Other motor configurations are available for improved heat reduction including totally enclosed non vent (TENV), water cooled and air-to-air heat exchangers. Thank you for purchasing a Panasonic Inverter. 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 ⦠Problems could include an open fuse, incoming utility imbalance, transformer problems or feed-wire sizing. The higher the motor speed above base RPM, the less torque available from the motor. ), Load type (constant torque, variable torque, high inertia), Starting method (across the line, VFD etc. 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. 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