How to read squirrel cage induction motot data sheet

[MotorPump]

I'm new to electic motor, so I need some help in understanding provided specification. Thank you in advance.

1) I have a data sheet for a squirrel cage incution motor, but I'm not familair with these. This motor is working on 230V now.

From the following information, what is the NUMBER OF TURNS of the stator? 41T or 70T or combination of both?

|| LAP WDG || CONC WDG
=====================================
Turns || 41T || 70T
No. of Group || 6 of 4 || 6 of 2
GRP sequence || Even || Even
Span || 1-9 || 1-12, 2-11
Connection || 2Y-1Y || 2Y-1Y
Space factor || 51% || 41%
No. of leads || 9
HP || 2
Pole || 2
Volts || 230/460
Phase/Freq. || 3/60

2) I also have an 'Equivalent circuit data (3phase 230V)' sheet for same motor as in the above.

----[R1]--[X1]----[X2]---
| |
| |
[Xm] [R2/S]
| |
| |
----------------------------

Provided values in the circuit sheets are 'SLIP, I1, I2, R1, X1, R2/S, X2, XM, TOTAL R, TOTAL X, TOTAL Z, X/R RATIO' for FULL LOAD and LOCKED ROTOR.

From these info, how can I get resistances, (self and mutual) inductances of rotor (each bar) and each phase of stator? I'm planning to give these values to the simulation of the motor.

Thanks again

 

[davidbeach]

The diagram is per-phase. X2, R2/S are the rotor, Xm is the magnetizing reactance and R1, X1 are the stator. I'm not sure how they get 41 turns and 70 turns, but the 41 turn configuration is the 230V and the 70 turn configuration is for 460V.

 

[electricpete]

Actually I think 2Y is 230vac and 1Y is 460vac.

41 turns vs 70 turns has to do with lap vs concentric winding as shown by the table heading.

I agree with davidbeach for most purposes the equivalent circuit with elements R1, R1, X1, X2, XM is used for simulation of the overall behavior of the motor (for example torque vs speed, current vs speed, starting simulation etc). What kind of simulation are you trying to do?

=====================================
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[MotorPump]

Thanks for guidance.

My simulation is about state equations.

For example,...

d(x1)/dt = f(x1,x2,..
...,Rs1,Rs2,Rs3,...
...,Lsa,Lsb,...
...,Lra,Lrb,...
...,Lma,Lmb....)

where, x1,x2,...are states,
Rs1, Rs2, Rs3 are resistances of each phase,
Lsa (Lsb) is stator coil inductacne of alpha (beta) phase after park's transformation,
Lra (Lrb) is rotor coil inductance of alpha (beta) phase after park's transformation,
...and so on

If the 'Equivalent Circuit Diagram' is about PER-PHASE, Does that mean that I can use the value of [R1] in the diagram directly for Rs1, Rs2, and Rs3 in my simulation?

Even though it is true, I think I need to give some modification to the value of X1 , X2, and Xm because my simualtion has parameters for 'alpha' and 'beta' phase inductaces due to park's transformation. Am I correct?

Thanks again,

 

[aolalde]

The winding data you have is for two different types “LAP” and “CONCENTRIC” but they are equivalent. If the winding is lap the turns per coil are 41 and a fix span 1-9. For concentric winding the turns per coil are 70 and two concentric coil per group, that is the reason for different span 1-12, 2-11. Both windings are connected 2Y for 230 Volts or 1Y for 460 Volts operation.

The equivalent motor circuit is per phase. The voltage applied to the input is the line to neutral. The parameters provided could be in ohms or per unit if in ohms you should match them to the voltage. The suffix 1 stands for primary (stator) and 2 for secondary (rotor), the M is for mutual.

The easy and direct way to analyze the motor performance is by the equivalent circuit, the different states could be different slips ( eg s=0, 0.01,.5 etc) or different voltages ( eg V= 1, 0.9, 0.8, etc).

I am not familiar with your simulation equations but yes, the values are per phase and the resistances and reactances are the same for all three phases. Using the equivalent circuit normally you calculate one phase and the other two are exactly the same but 120 and 240 °E out of phase. The total power is 3 times that per one phase. May be some of the inputs in your simulation are zeros for a 3 phase motor.

 

[ijl]

Assume that there are three windings in the stator, and three windings in the rotor, one for each phase. (Does not sound much like a squirrel cage, but seems to be OK in simulations). Use the following notation:

Lss self-inductance of one stator winding
Mss mutual inductance between stator windings. It is negative. It is often assumed that Mss = -0.5Lss
Lrr' self-inductance of one rotor winding, seen from the stator side. That is, the transformation ratio between stator and rotor windings is taken into account.
Mrr' mutual inductance between the rotor windings, as seen from the stator side. Again, typically Mrr' = -0.5Lrr'
Lsr (maximum) mutual inductance between one stator winding and one rotor winding
Rs resistance of one stator winding
Rr' resistance of one rotor winding, as seen from the stator side.

With this notation for the inductances and resistances, and your notation for the parameters of the equivalent circuit, the connection between the inductances and resistances and the parameters of the equivalent circuit is:

R1 = Rs
R2 = Rr'
X1 = j w (Lss – Mss – 1.5 Lsr)
X2 = j w (Lrr' – Mrr' – 1.5 Lsr)
Xm = 1.5 Lsr

See also program motdatpr at

http://pp.kpnet.fi/ijl/prog.htm