# Synchronous Speed to Shaft Speed

1. Oct 2, 2016

### Sirsh

Hi All

I have a standard induction motor torque vs. synchronous speed diagram and I want to calculate the shaft-speed at any point along the curve (from 0% synchronous speed to 100% synchronous speed). I know that the synchronous speed is 1500 rpm at 95% synchronous speed (which is also at full-load), at full-load the induction motor experiences 5% slip.

Now, I know that the equation nshaft = nsynch*(100-%slip) will give me the shaft speed at full-load, but I also know that the slip changes as per the amount of torque/synchronous speed.

At 0% synchronous speed there is 100% slip and at 100% synchronous speed there is 0% slip.

Is there any method to how you can calculate the shaft speeds on the information i've presented? 1500rpm synch speed and 5% slip at full-load.

2. Oct 5, 2016

### Hesch

Yes, I think you can calculate it, at least by numeric methods ( computer simulation ).

You may find an approximate result, using circle diagrams.