If the motor doesn’t rotate in two-phase operation, find the reason for phase loss and eliminate it. When a motor is “grounded“, the winding is shorted either to the laminated core or to the motor’s frame. These faults require rewinding or replacing the motor. 3. In this starter motor is running in star winding during start, when motor get full rpm, winding convert in to delta winding. For interlocking with delta contactor also connect NC point of delta contactor (C3). Step1:- line voltage(R,Y,B,) connect in MCB input and then MCB output connect to overload relay input. You should be seeing 240V between all of the wires coming from the wall. I have a 6 leed motor how do I find U V W. First check continuity between wire, Two wire will show the resistance, these two wires are first winding of the motor. Apr 29, 2015 #1 Welcome to ElectriciansForums.net - The American Electrical Advice Forum Head straight to the main forums to chat by click here: American Electrical Advice Forum. They can be repaired, recast, or rebarred (if it’s economical). Here overload relay is use for protection from heavy current. A rotor with the same diameter but longer than the original will work, but some efficiency is lost. If we found continuity between earth and winding, motor is faulty. Check mechanical load on motor, Load should be smooth or not in jam condition. Some motors (up to 5 horsepower) are wound with no insulation separating the phases. For cost cutting and easy maintenance we always use 220v operated items. Insulation also separates the coils of each phase in the slots. Testing and inspection of surge protection devices. The increased amperes are similar to a misaligned rotor and stator iron. Motor faulty. These winding problems may be found in a three-phase motor: Shorted turns; Ground (winding shorted to frame) Phase-to-phase short; Open winding; Burned windings from operating on single phase; Submerged motor; Assorted rotor problems: Open rotor bars; Open end rings; Misaligned rotor/stator iron; Rotor dragging on the stator; Rotor loose on shaft Once you have tested a few 3-phase motors, the process will come easily. Then again check remaining 4 wire, then two wire will show the resistance it is 2nd winding and rest of two wire is third winding. Possible causes of a misaligned rotor include: If the rotor drags on the stator and the bearings aren’t worn, it’s common practice to “skim” the rotor on a lathe. For example, if the motor is drawing 30 amps at 250 volts, you have 30 x 250 x sqrt 3 (about 1.73) = 12,975 watts). Most induction motors are started using direct online starter, but when very large power motors are started using DOL, they take large starting current. Motor, rotor and physical movements are ok. Pump keeps giving same watee out put. Among the causes of interphase breakdown are contaminants, tight fit (in the slot), age, mechanical damage, and high-voltage spikes. The cutting head and rotor are one piece, just swapping motors is not an option. Being a 3 phase there are no condensers or start switches to check. This dust is oxidized iron, caused by the rubbing action between the shaft and the rotor iron. The coils don’t share the slots with other poles in some concentric-type windings. See Figure 12. Figure 5 is an end coil phase-to-phase short. 6 wire of winding is coming from motor as U1, U2, V1, V2, W1, W2. If the motor has ball bearings, they should be replaced. By checking the supply voltage, current, and frequency first, you can rule out problems that might affect the motor drive or breaker circuits. In addition, by identifying over or under voltage conditions, you can avoid nuisance tripping of drive fault circuits and eventual damage to the motor drive itself. Calculate three-phase motor power consumption by multiplying amps by volts by the square root of three (W = AV(sqrt 3). Due to large current, they cause disturbance in supply voltage.