Double speed three phase asynchronous motor winding classification A single layer winding: Single-
layer windings is each embedded in the stator slot only buy a coil winding, on the edge of
effectively, so it only total coil motor half of the total number of slots. The advantages of the
single layer winding is winding coil number less process is simple; Utilization of the interlayer not
denied because trough increase; Single layer does not happen and breakdown failure, etc. Drawback is
the winding of the electromagnetic wave shape is not ideal, motor iron
ac synchron motor loss and noise are large
and starting performance also is a bit poor, so the single layer winding asynchronous motor only commonly used for small capacity. In accordance with the single layer winding coil shape and arranged termination local arrangement is different, can be divided into chain winding, cross chain,
concentric windings and intersection concentric winding winding types, etc. 1 chain chain windings
is by having the same shape and width of single coil components, due to its winding ends each coil
like set up the link of the name. Should pay special attention to single chain winding of the coil
pitch necessary for odd number, otherwise will not be able to arrange the winding arrangement. As
per each phase 2 cross chain winding slot number nine is greater than 2 odd number will not be able
to arrange the chain winding arrangement, at this time will need to use the intersection with single
and double coil winding.
Three concentric winding in the same group of extremely all coil around the
same circle. When each ac synchronous motorphase slot number per level 4 Q is greater than 2 even can adopt the form of cross
concentric winding. The advantages of single-layer concentric winding and cross concentric winding
for winding, is relatively simple, embedding a long use wire end of faults is too much. Now except
for useful in small capacity of 2, 4 pole motor, is now rarely use this winding form. Double
cascading winding Single and double layer composite winding Star connection relationship with the
Angle joint When the star of by change Angle: the original star connection wire diameter total
cross-sectional area divided by 1.732 is equal to the Angle of the wire diameter total cross-
sectional area. The Angle of by change star: when the original Angle joint line diameter when the
total cross-sectional area multiplied by 1.732 is equal to the star connection wire diameter of the
total cross-sectional area. The difference of star connection with nature Angle joint When star
connection line voltage equals 1.732 times the phase voltage, phase current is equal to the line
current. Angle joint when the phase voltage is equal to the line voltage and line current is equal to
the phase current of 1.732 times. With the power of the motor, when the star connection, wire
diameter thick, less number of turns, the Angle joint, fine wire diameter, number of turns. When the
Angle joint sectional area is 0.58 times of star connection. When the Angle joint line diameter when
the total cross-sectional area divided by 0.58 is equal to the star connection wire diameter of the
total cross-sectional area. When the star connection wire diameter total cross-sectional area
multiplied by 0.58 is equal to the Angle of the wire diameter when total cross-sectional area)
cross-section of wire diameter calculation formula: cross-sectional area S = square multiplied by
0.785 is the diameter of the motor internal connection with salient pole and ordinary pole, salient
pole and ordinary pole is determined by the design properties of the
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not be changed motor no-load current coefficient calculation.
Lack of phase operation reason (1) the star connection broken a phase power supply.(a) as shown in figure 8,when the motor is running,for some reason,there is a phase circuit (such as W phase winding in the L3 disconnect),then in the W phase winding current,two phase winding become series relationship between rotor and stator U and V,pick up on the 380 V voltage,while two flows winding the same current,which is lack of phase operation.The motor still can continue to operate,but the work of the two phase winding,on both ends of each phase voltage is 190 v (phase voltage 220 v) in normal working conditions.Due to the phase voltage is reduced,rotating magnetic flux are reduced accordingly.But the load constant,the output torque of the motor is constant,so the stator current will increase.In addition,according to the analysis of power Angle of the normal work of the motor,three-phase winding average burden of power will increase,the winding current must be increased.In short,a phase winding,when the power is the single phase asynchronous motor burden of the remaining two phase winding.At this point in the winding current value is greater than the motor overload current,but smaller than short circuit current.
(2) delta connection broken a phase power supply.(b) as shown in figure 8,if L3 disconnect,then pick up the entire winding between two phase,which is lack of phase operation.Although the three-phase windings are working at this time,but they ac geared motor have not symmetric winding,but M phase winding facies V phase winding in series,and then winding parallel with U.In this case,the current in the winding,power is not tight and normal power current,power is different at work.Two branch current is not balanced.The theory and practice have proved that winding to delta connection,once broken a photograph,can form large circulation inside the motor winding,a very short time will burn out motor winding,the harm than y connection of motor open phase running is more serious.(3) delta connection within a phase of winding circuit.(c) as shown in figure 8,when the two phase of the motor winding form v-shaped connection,this connection,the starting torque is too small.The original ban motor starting; The motor is running,and the cut-off current is 0,is not to do work,the rest of the two phase winding load is aggravating,current increases,increased winding temperature rise.
