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What would happen to a three phase motor if two of the three phases were reversed?
Wiki User
∙ 14y ago
Yes and no. A motor will continue to run but at a lower efficiency that when three phase is applied but it is not reccommended leaving it in this condition. It is usually demonstrated in electrical course classrooms to show that it will work. A three phase motor will not start by itself with just two phases connected. Another classroom demonstration is connecting the motor in a single phase supply (two of the three phases) and starting the motor with a rope wound around a pully on the shaft. Pull the rope like starting a gas engine and the motor will run. When a phase is lost the other two leg currents will go high, this high current is what can burn the motor out. Contactors today monitor all three phases and are protected with overload heaters. These heater blocks have auxiliary normally closed (N.C.)contacts on them. The start circuit is wired in series through these N.C. contacts which is in series with the contactor's hold in coil. If any of the three phase legs that are monitored draws a higher current than what the heater blocks are rated for the auxiliary contact on the block opens and de energizes the contactor's coil. This action disconnects the motor's supply voltage from the motor and stops the motor before any damage is done to the insulation of motor's coil windings.
Wiki User
∙ 12y ago
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Why is the winding of the second phase reversed in the 3 phase synchronous motor?
That might be to make it run the right way.
What should you do if a three phase motor or compressor is not rotating in the correct direction?
If your three phase motor runs backward, you have two phases swapped. double check a, b and c phase to find which ones are misplaced.
What does the phases on a nameplate of a motor mean?
On a three phase motor, the phases give you direction for how to hook the motor up to make it spin one direction vs. the other. If you hook up such a motor blindly with all three phases, it may spin in the opposite direction you want; to fix, you swap any two of the three phase connections.
Can a 3 phase motor be converted into a single phase motor?
A three-phase motor will not start if one or two phases aren't connected. If while running one or two phases "drop out", it will continue to run for awhile, but will eventually burn out, unless connected to a motor saver.
Why motor burn at single phasing?
A 3-phase motor will not run on single-phase power or if one of the three phases is disconnected. If the motor is not running, there is no back-EMF generated in the coils, and they draw excessive current, thus overheating.
Will an ac motor run backwards if polarity is reversed at the outlet?
No, unless it is a three phase motor and you reverse only two of the phases.
What would cause an electric motor to run backwards?
Motors running backwards: A DC motor wired backwards or magnetic field reversed. 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.
Why three phase motor run in reverse even if it is not wired to run in reverse direction?
If a three phase motor in running in reverse, then one of the phases is reversed, plain and simple. If the wiring is correct at the motor, perhaps the phase reversal occurred someplace else.
What will happen if winding resistances of a motor are different?
The motor will pull different amounts of power on the different phases, which will result in not operating smoothly for three phase motors.
How direction of a split phase motor can be reversed?
reverse wires
Theory for brake test on three phase induction motor?
why three phase induction motor is delta connected
Why is the winding of the second phase reversed in the 3 phase synchronous motor?
That might be to make it run the right way.
What should you do if a three phase motor or compressor is not rotating in the correct direction?
If your three phase motor runs backward, you have two phases swapped. double check a, b and c phase to find which ones are misplaced.
What does the phases on a nameplate of a motor mean?
On a three phase motor, the phases give you direction for how to hook the motor up to make it spin one direction vs. the other. If you hook up such a motor blindly with all three phases, it may spin in the opposite direction you want; to fix, you swap any two of the three phase connections.
What will happen to a 208 volt 3 phase pump motor if one hot lead is not connected?
it will run on two phases but with higher amps. This is called single phasing. The motor will attempt to use the same amount of power, so the current will go up in the other two phases, which can cause the motor to burn out.
Can a three phase motor work on single phase power with out burning up?
A three phase motor will not operate on single phase. The motor will run on two phases but will not start. Motors running on just two phases is called single phasing. The line current of the two legs will go high and it is this factor that the motor controller uses to trip the contactor to open the circuit and isolate the motor from the power source.
Can a 3 phase motor be converted into a single phase motor?
A three-phase motor will not start if one or two phases aren't connected. If while running one or two phases "drop out", it will continue to run for awhile, but will eventually burn out, unless connected to a motor saver.
