Motors in symmetrical fault analysis
If you have induction motor load you can include it in your short circuit calculation for the sub-transient timeframe.  If you don’t have nameplate data you can estimate the sub-transient impedance of induction loads by assuming their sub-transient current is six per unit.  You can ignore them for transient and synchronous timeframes.

If you have synchronous motors present you would include them just like you would include synchronous generators.

You might find this interesting regarding Utility Reclosing and motor loads.

When you are setting instantaneous protection elements, or calculating maximum fault current, this is when you would consider induction motor loads contribution.  If you are concerned with slower protection elements then you can ignore them as their contribution is gone in a couple of cycles.

Russ 

p.s.  This would be a good place for you to begin studying this topic.