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You use a megger. This allows you to check what the condition of the insulation of the motor windings are. An ohms check on each phase should be an easy way if it reads OPEN then there's your bad phase. Otherwise there are diffrent types of 3 phase motors, could be the brushes, commutator, sliprings, many many things.
Wiki User
∙ 14y ago
Wiki User
∙ 12y agoThere should be around .1 ohms of resistance from any winding lead to any of the others. But there should never be any reading of resistance from any lead to ground (motor case).
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What are the advantages of three phase induction motors over the other motors?
A Single phase induction motor includes a main winding, an auxiliary winding, a run capacitor, & a subsidiary star device. The auxiliary winding is configured such that the number of turns of the aauxiliary winding through which a current flows, varies according to the operating mode of motor. When the motor starts, the number of turns of the auxiliary winding through which a current flows is reduced there by increasing the start efficiency of the motor. when the motor runs in normal mode, the number of turns of auxiliary winding through which a current flows is increasing there by increasing the operations efficiency of motor
What is three phase winding?
they are winding wound in such a way that they deliver three times the power
What are the possible causes if load is not same on all the three phases?
You may have single phase loads on one winding, turn to turn faults within one winding, the three phase voltage applied to the transformer may not be balanced, and so on. If you have only three phase loads attached, and the load impedance is not balanced, you may have a partially failed piece of equipment. Part of one of the motor windings may be shorted out, for example.
What is the use of centrifugal switch in single phase induction motors do all single phase motors gave them?
To stop a three-phase motor dead ('plugging'), rather than allowing it to slow to a stop, the motor controller interchanges two of the three lines -which applies a reverse torque to the machine. But before the motor then gets a chance to reverse direction, the centrifugal switch trips the starter and removes the supply. <<>> The centrifugal switch that you refer to and can see in an open frame motor, is used to open the start winding of small HP single phase motors. Once the motor gets up to a certain RPM, the switch opens and the motor continues to operate on its run winding. When the motor stops, the switch goes back to its normally closed position in the start winding and awaits the next start operation.
Can you run a star motor in delta?
Delta motors should have more starting current than Wye (Star) motors because Delta motors have two windings to take current per phase -- they are wired Phase to Phase. Star motors have only one winding per phase -- they are wired Phase to Neutral.
What is three phase winding?
they are winding wound in such a way that they deliver three times the power
What are three phase motors?
Three phase motors are motors which operate under three phase supply.Each phase is displaced from one another by 120 degrees.It produces three fluxes which are also 120 degrees displaced.
What are the advantages of three phase induction motors over the other motors?
A Single phase induction motor includes a main winding, an auxiliary winding, a run capacitor, & a subsidiary star device. The auxiliary winding is configured such that the number of turns of the aauxiliary winding through which a current flows, varies according to the operating mode of motor. When the motor starts, the number of turns of the auxiliary winding through which a current flows is reduced there by increasing the start efficiency of the motor. when the motor runs in normal mode, the number of turns of auxiliary winding through which a current flows is increasing there by increasing the operations efficiency of motor
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.
What are the possible causes if load is not same on all the three phases?
You may have single phase loads on one winding, turn to turn faults within one winding, the three phase voltage applied to the transformer may not be balanced, and so on. If you have only three phase loads attached, and the load impedance is not balanced, you may have a partially failed piece of equipment. Part of one of the motor windings may be shorted out, for example.
Why would three phase be used instead of single phase?
Three phase electricity is used instead of single phase for industrial situations. Industries use three phase electricity instead of single phase to operate electric motors driving heavy machinery. Three phase electrical motors produce more power from the same amount of electricity and maintain steadier speed. Small portable motors such as drills and mixers use single phase. Motors used around the house are single phase. Motors used to run large industrial machines use three phase.
What is a y configuration on a 3 phase circuit?
On a wye connection all three ends of the phase winding coils are connected together and grounded. The other end of the three phase winding are connected to the supply voltage.
What is the use of centrifugal switch in single phase induction motors do all single phase motors gave them?
To stop a three-phase motor dead ('plugging'), rather than allowing it to slow to a stop, the motor controller interchanges two of the three lines -which applies a reverse torque to the machine. But before the motor then gets a chance to reverse direction, the centrifugal switch trips the starter and removes the supply. <<>> The centrifugal switch that you refer to and can see in an open frame motor, is used to open the start winding of small HP single phase motors. Once the motor gets up to a certain RPM, the switch opens and the motor continues to operate on its run winding. When the motor stops, the switch goes back to its normally closed position in the start winding and awaits the next start operation.
How does a star winding shifts to a delta winding in a three phase motor?
u can change in the terminal box..
Can you run a star motor in delta?
Delta motors should have more starting current than Wye (Star) motors because Delta motors have two windings to take current per phase -- they are wired Phase to Phase. Star motors have only one winding per phase -- they are wired Phase to Neutral.
How do star and delta configured three phase induction motors perform differently?
Star Delta starter control wiring ensures that initially the Motor winding is connected in Star and after set timer (few seconds) the winding gets connected in Delta automatically. There three power contactors and timers to make it happen.
What is open phase in induction motors?
The field windings of a three-phase motor are termed 'phase windings'. An 'open phase' means that one of these windings has become open-circuited -i.e. there is a break in the winding. Unfortunately, however, 'line conductors' are often incorrectly referred to as 'phase conductors', so a break in a line conductor could (incorrectly) be called an 'open phase'!
