The three windings are made the same to maintain a balance in the motor.
Resistance of stator winding is the resistance of the copper conductors being used for building the windings of three separate phases, i.e. R-Y-B. These windings are marked like U1-U2, V1-V2 & W1-W2 at the motor terminals (6 nos.) for the three phases, i.e. R-Y-B respectively. We have simply to measure the resistance of each winding by using a multimeter by connecting the terminals (2 no.) to U1 & U2 and so on. The resistance should be in ohms not milliamps [amps is form of measuring current not resistance] milliamps to microamps in case of large motors, it may be in amps in case of small sized motors. But resistance of each winding should be nearly same to each other. This shows the electrical balance among windings & also proves the healthiness of the winding.
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.
The higher-voltage winding has more turns (therefore its conductor will be longer) than the lower-voltage winding and, because it will carry less current, its conductors will have a lower cross-sectional area. Consequently, the higher-voltage winding will have a higher resistance than the lower-voltage winding.
That sounds quite good since the main winding should be insulated from the case. 10Mohm is a very large resistance it is well within normal range of the motor.
hi.. this is pankaj working as power engineer. we have a 11 kw induction motor which is used in fluidising blower. its no load current i sarround 9.5 to 10.6 amp. and under load its ampere does nt exceed 15 amp. its winding resistance is 1.4 ohm.
Resistance of stator winding is the resistance of the copper conductors being used for building the windings of three separate phases, i.e. R-Y-B. These windings are marked like U1-U2, V1-V2 & W1-W2 at the motor terminals (6 nos.) for the three phases, i.e. R-Y-B respectively. We have simply to measure the resistance of each winding by using a multimeter by connecting the terminals (2 no.) to U1 & U2 and so on. The resistance should be in ohms not milliamps [amps is form of measuring current not resistance] milliamps to microamps in case of large motors, it may be in amps in case of small sized motors. But resistance of each winding should be nearly same to each other. This shows the electrical balance among windings & also proves the healthiness of the winding.
Reverse resistance should be infinite.
You test an ignition coil by checking the resistance with an ohm meter. The resistance values should be something like, Primary winding .3 to 1 ohms, Secondary winding 8,000 to 11,500 ohms.
Dc voltage level should not exceed the current carrying capacity of the winding. since winding resistance is very small. We need to be careful in giving the dc voltage to transformer winding.
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.
The higher-voltage winding has more turns (therefore its conductor will be longer) than the lower-voltage winding and, because it will carry less current, its conductors will have a lower cross-sectional area. Consequently, the higher-voltage winding will have a higher resistance than the lower-voltage winding.
Zero ohms.
The primary and secondary windings of a mutual transformer are electrically isolated, and should have 'infinite' resistance between them when measured appropriately (which depends on voltage ratings of the windings).
If an Alternating Current (a/c) motor is bad. The resistance will read very hi as in an open winding. ie: meg ohms Or very low as in a shorted winding. ie: 0.01 ohms It must not read any resistance to the housing or shaft. The resistance between leads should be a reasonable value and can be determined with : electromotive force divided by inductance equals resistance. example: 215 volt alternating current with name plate full load amperes of 10 should read very near 21.5 ohms resistance between leads.
A megger is an electrical instrument that is used to measure the resistance of insulation by applying a DC voltage to the conductor. One lead is connected to the conductor and the other lead is connected to ground. Safe insulation reading to ground should be above 2,000,000 ohms or 2 megs.
That sounds quite good since the main winding should be insulated from the case. 10Mohm is a very large resistance it is well within normal range of the motor.
Actually, measuring winding resistance with a multimeter is an iffy situation at best. This is because the multimeter will not tell you if one of the turns is shorted, causing Q to drastically suffer, it will really only tell you if the winding is open, or if it is shorted to something it should not be shorted to, such as the frame. This is especially true for larger windings, in larger transformers and motors, because their DC resistance is so close to zero that you might not be able to tell if they are shorted or normal. Using a multimeter is a good start, to make sure that basics are covered, and it might tell you if the winding is dead shorted, but you need to know for sure what the expected DC resistance is, and you need to know that you multimeter is very good in the low Ohms scale.