How to judge the running state of asynchronous motor according to slip rate?

How to judge the running state of asynchronous motor according to slip rate?

In electrical engineering, slip is generally expressed as S
1. The rotor speed is lower than the rotating magnetic field speed, and the direction is the same, the electromagnetic torque is the driving property, the motor is in the motor state, and the slip is 0

Calculating the rated slip of three phase asynchronous motor
What is the rated slip SN of an 8-pole three-phase asynchronous motor with rated speed n = 720rpm and power frequency f = 50Hz? What is the calculation formula,

First of all, the synchronous speed (motor speed under ideal state) n = 60F / P must be calculated. In this formula, f is the power frequency, which is generally 50 Hz, P is the number of pole pairs of the motor, and 4 is the synchronous speed of 750 rpm When the slip formula s = 750-720 / 750 (the ideal speed is obtained by subtracting the actual speed from the ideal speed), the slip is 0.04

2. There is a three-phase asynchronous motor with frequency of 50 Hz, rated speed = 730 R / min, no-load slip s = 0.002 67. Try to find the number of poles, synchronous speed, no-load speed and slip under rated load

1、 Series: (int is the integer symbol)
p=INT（60f/nN）
=INT（60*50/730）
=INT4.109589041095890410958904109589
=4
P is the number of pairs of poles, 4 pairs of poles (one pair of poles is the opposite two poles)
2、 Synchronous speed:
n=60f/p
=60*50/4
=750r/min
3、 No load speed:
n1=60f/p*（1-s）
=60*50/4*（1-0.00267）
=747.9975r/min
4、 Rated load slip:
NN = 60 * f / P * (1-s rated)
S rated = 1-NN * P / 60 / F
=1-730*4/60/50
≈0.026666666666666666666666666666667
5、 In addition, don't mention the same question twice. It's a waste of points. Ha ha, remember to give points

A three-way asynchronous motor, its rated speed n = 975r / min, power frequency f1 = 50 Hz?
There should be steps

975rpm is close to 1000rpm, so the number of motor poles is very small
P = 60 * 50 / 1000 = 6 poles
The number of poles is 3
Slip s = (1000-975) / 1000 = 0.025

The rated frequency of a three-phase asynchronous motor is 50 Hz and the rated speed is 1440 / min. the synchronous speed, slip and electromotive force frequency of the motor are calculated?

Synchronous speed 1500 rpm. Slip: 60 / 1500 = 0.04
Rotor electromotive force frequency: 50 Hz x 1440 / 1500 = 48 Hz

2. There is a three-phase asynchronous motor with frequency of 50 Hz, rated speed NN = 730 R / min, no-load slip s = 0.002 67. Try to find the number of poles, synchronous speed, no-load speed and slip under rated load

1、 Series: (int is the integer sign) P = int (60F / NN) = int (60 * 50 / 730) = int 4.109589041095804109589041095889 = 4, P is the number of opposite poles, 4 pairs of poles (one pair of poles is two opposite poles), so the motor is an 8-pole motor

Calculate the power factor and slip of the motor and get the solution~
Y200m-6 three-phase asynchronous motor, rated output power P2 = 30kW, rated voltage U1 = 380V, I1 = 57A, efficiency η = 92%, rated speed NN = 960r / min, f = 50Hz, calculate motor power factor and slip
Such as the title, seek expert solution ~ thank you very much

Synchronous speed n = 3000 / 3 = 1000r / min, slip = (n-ne) / N = (1000-960) / 1000 = 0.04
η=P/（√3*U*I*COSφ）
Where p - is the output power of motor shaft, u - is the line voltage of motor power input, I - is the line current of motor power input, cos - is the power factor of motor
COSφ=P/（√3*U*I*η） =0.8692

If the rated speed of a three-phase asynchronous motor is 1470r / min, what is the number of poles, synchronous speed and slip of the motor?

The synchronous speed of 4-pole motor is 1500, and the slip is 0.02

The rated speed of a three-phase asynchronous motor is 1440 R / min, and the power frequency is 50 Hz

S = (N1-N) / N1, where N1 is synchronous speed and N is motor speed
=（1500—1440）/1500
=0.04
There are two pairs of magnetic poles

It is known that the speed of a three-phase asynchronous motor is 1440r / min when the power frequency is 50 Hz under rated condition
It is known that the speed of a three-phase asynchronous motor is 1440 R / min when the power frequency is 50 Hz under rated condition
(1) Please determine the synchronous field speed of the motor?
(2) Frequency of rotor current at rated operation?

Synchronous speed N0 = 60 f / P = 60 × 50 △ pole pair = 60 × 50 △ 2 = 1500 rpm
The rotor current frequency is: F2 = f * s = f * [(N0 NN) / N0]
(Note: N0 synchronous speed, f power frequency, P pole number, F2 rotor current frequency, s slip, NN asynchronous speed)
Slip s = (N0 NN) / N0 = (1500-1440) / 1500 = 0.04 = 4%
Frequency of rotor current F2 = f * s = 0.04 * 50 = 2Hz
The frequency of rotor current F2 = f * s = f * [(N0 NN) / N0] = 50 * [(1500-1440) / 1500] = 2Hz