Switching the polarity of the input voltage will cause a simple DC motor to run in the reverse direction. Once you hear a scroll run backwards you’ll know it’s running backwards. ... You can't wire residential AC hand held power tools backwards and make them run in reverse by doing so. A phase failure is an interruption of a single conductor. Small to medium sized motors are mostly stator critical – this means that only the stator can be damaged. 3-Phase Motors used on Molten Metal Pumps. When changing the motor voltage, that is done on the motor terminal board and no mater how you rearrange those wires, you cannot force the motor to run backwards. Try a battery with a 123 231 312 132 321 213 Three of those are going to make the motor run one way, three will make it run the other. Check external cooling fan to be sure air is moving properly through the cooling channels. If the motor has wires already attached, connect the white wire to the positive end of the battery and the black wire to the negative end. I told him in was probably just spinning backwards. An open rotor can cause a pulsation in the output torque of a motor as the open rotor bar passes under each phase of the motor winding. Easily controlled by an variable frequency drive (VFD) often called an inverter. I am not an expert, but this is what I … Of course that doesn't mean that the single phase loads have not been expanded to the point where they caused the voltage imbalance, but I would expect two legs with a lower voltage if that was the case. The easiest way to prevent 3-phase motors and scroll compressors from running backwards if the power company reverses any 2 legs of the phase to the building is to add a phase monitor to the system. They may be part start or use other “soft” starting strategies and there may be capacitors used for power factor correction but neither of these are the same as the good old single-phase run capacitor… so that’s a plus. A 3 phase AC motor with 2 phases reversed A single phase motor will run either way unless it is 'persuaded' by means of a shaded pole or other method to rotate in a particular direction. I did high resolution and there is no side band which is confirmed there no winding problem. Cleaning and baking the windings may be all that’s needed. If a three-phase motor has been submerged in water but not energized, there’s a good chance it won’t need rewinding or replacing. Single phasing (three phase only) Check the current at all phases. 4 wires coming out of the motor. Now, you have two more pumps so we may be able to check this with a clamp type ammeter (commonly called an amprobe). Excellent torque and power efficiency ratings. This is called Single phasing. if the rpm's look about right, correct the problem with a new fan blade thats meant for the rotation... a little cheaper than a new motor andless work. Swapping phase A with phase B re-orders the fluxes so that the flux rotates in the opposite direction. Is this a problem? The cause is, for example, blown fuse. The motor then continues running with two phases and can suffer damage. Some of the single phase motors have an option to hook up to reverse the run. I have electrical motor three phase, vibration symptoms in this motor as fallows; 1-Twice running speed is excitation with running speed at 1800 rpm. Remember the windings make up an electromagnet. I never said it was a three phase motor I only said that you can reverse the direction of an AC motor if it is 3 phase. Submerged Motor. Fan performance is wrong. A polarity change of one phase in relation to the other two in a typical three phase generator feed system that is functioning properly is impossible. Co woker called and said one condenser fan was running backwards on a 20 ton trane ac causeing unit to trip on high head. 2) Supply Voltage Is Low (Less Than 415 Volt In Any Of 3 Phases). The motor now runs in reverse because two of the phases have been swapped. If due to some reasons, one phase of the motor gets disconnected, the motor will continue to run from the active 2 phase supply. 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. If one phase is lost, it normally will not start, but if it is already running when one phase is lost, then it may continue running under light load. Make sure the rotation is the correct way for the indoor blower motor … Phase failure. Troubleshoot A 3-phase Electric Motor. There are ways, albeit not very efficietnt, to run a three phase motor on single phase 220 volt current, but, if your wall outlet is 115 volts, it is an unworkable situation. All it takes to reverse a 3-phase motor or compressor is to switch any 2 of the power legs. When a three phase motor looses one of the phase supply voltage then it is called Single Phasing. I checked current phase and found the following> phase A is 121A phase B is 118 A phase C is 130 A The local utility calls the two transformers the "lighter" and the "kicker", with the lighter supplying the single phase loads and the kicker adding the third phase for the 3 phase loads. Occasionally an excessive reverse torque will actually make the motor run in reverse. Improper ventilation. Switching the starter winding leads will cause a single phase AC motor to run in reverse. Three phase motors on a three phase three wire system only need two line and motor leads interchanged to reverse the motor rotation. the motor is old, not sure if its original. If the motor does not turn, it's possible that your battery is not sufficiently powerful to run the motor. he said no because its has voltage at motor plus it was pulling a amp draw. Temporarily attach the motor to a battery to make sure everything is operational. What breaker do you have for it, 2 pole? Motors running backwards: A DC motor wired backwards or magnetic field reversed. 3. Go back to Contents Table ↑ 6. Unbalanced voltage (three phase only) Check the voltage at all phases. If there is excessive dirt build-up, clean the motor. Causes of inadequate airflow to the fan include a backwards installed or running impeller, improper blade angle setting, missing cut-off, an impeller not centred with inlet collars, slow fan speed, dirty or clogged inlet, improper running clearance or improper inlet cone-to-wheel fit. The windings in a 3 phase motor, when activated by a 3 phase supply produce a rotating magnetic field in the rotor area of the motor. Only if a capacitor was replaced and had the necessary terminal connections, then perhaps someone could accidentally rearrange the wiring to get the motor to run backwards. I went to use my 1933 8" jr. for the first time and the motor runs in reverse. Before drawing any conclusion, check the line-to-line voltage. Three phase motors need all three phases to run reliably. Edit: also, if you need to swap the power to the compressor then you’ll most likely have to change 2 legs of power on the indoor blower motor aswell. Edited by Alex the Electrician on 4/10/2010 at 1:17 PM EST. At work we had an electrician come and replace the electrical box out back and when we turned the AC on, it worked, but barely. 3 phase 400V motor run on 230V single phase supply. 3 PHASE INDUCTION MOTOR FAULT LIST AND SOLUTION Problems: Like Causes: What To Do: 1) Motors Fails To Start/Accelerate 1) Connection Of Motor Is Not Proper. A three phase induction motor is a type of AC induction motors which operates on three phase supply as compared to the single phase induction motor where single phase supply is needed to operate it. single phase will not run backwards only 3 phase can. These motors provide: A wide range of power options from 0.5 hp (0.37kw) to 30 hp (22kw.) 1) Check The Connection Of Motor. often most motors the rotation is if you were looking at the butt end of the motor unless it says cwse or ccse that woull be shaft end of the motor. If it is a 3 phase induction motor you can reverse the rotation by switching any two of the three wires. 2) Maintain Proper Supply Voltage By Using Autotransformer Or Transformer Tap Changer. As long as you have the windings grouped correctly (Phase 1 and 3 together and Phase 2 and 4 together) the worst that will happen when you go to run the motor is that it will run backwards. The interaction between the inductance of the motor windings and the capacitor's capacitance causes that winding to be about 90 degrees out of phase with the main winding. i tried wiring it different but to no avail. Remember, there are 6 ways to connect a three wire, three phase motor. Nearly all the electric motors we ship with our pumps are 3-phase induction type motors. Figure 11 – A delta-connected motor that failed because of a single-phase condition, Line 3 is open. The 3 phase motors must be connected to rated voltage and load for proper working. ... Hello .. it is very strange that a 220volt single phase motor would be turning "backwards" as … We went on the roof where the unit is and noticed it was in thermal overload, so we cooled it off, then turned it back on and noticed it was running backwards? By definition three phase power is AC only, not DC. Three-phase motors are normally used in commercial-type operations. Since one of the phases is now disconnected, current through other two phases will increase to produce the desired torque. The direction of rotation of any three-phase motor can be changed by reversing 2 of its stator leads. This causes the direction of the turning electromagnetic field to reverse. With the main winding creating a magnetic field that alternates vertically, and the other winding creating a magnetic field that alternates horizontally but out of phase, the sum of these is a spinning magnetic field. Three-phase motors (also annotated numerically as 3-phase motors) are widely used in industry and have become the workhorse of many mechanical and electromechanical systems because of their relative simplicity, proven reliability, and long service life. These motors have fewer parts and are more sturdily built than their single-phase counterparts. It should be approximately the same. In this video you'll find out how to connect three phase motor to single phase power supply. Restore the power. If it is more than 10% above the motor rated voltage, it could be the cause of the high full-load speed and possibly the high current. It is about 208 volts. its 1/3 hp 1750 rpm's 110/220v. When replacing a motor, many wonder about the color code for the wires. A 3 phase motor will run in reverse by switching one leg of the input power. Test the motor and battery. Single Phasing a case when any one phase out of the three phases fails. When a motor is linked to a device that will not be damaged when its motor rotation is reversed, power can be momentarily applied to the motor to observe its direction of rotation. If it is single phase then the motor usually has a third wire that will reverse rotation. Be careful, running a condenser backwards may cause damage. cause circular saws normally spin counter-clockwise. 3-phase motors don’t require run or start capacitors as having 3 phases solves all those issues.