typical Locked rotor/Nominal current ratio for synchronous motor 3

[ta5531871]

I have no vendor data yet and I need to model a synchronous motor, so I need a Typical Ilr/In ratio and reactance for 4500HP motor

 

[aolalde]

The manufacturing standards like NEMA MG1 do not define the starting current of Large Synchronous Motors. The manufacturer provides the “Code Letter” which means the kVA per HP demanded at starting with full voltage.

Expect around 5.7 kVA/HP (Code G) for a motor 4,500 HP. This will result in
25,600 kVA starting at full voltage.

For 4160 volts, I start = 25,600/(1.732*4.16) = 3560 amperes.

The synchronous reactance depend on the PF design (1.0 or 0.8)
Typical reactance values are:

Xd =1.25 to 1.3 p.u.
Xq = 0.75 to 0.8 p.u.

 

[jbartos]

Suggestion: Reference:
Charles Concordia "Synchronous Machines Theory and Performance," General Electric, 1951,
often uses:
Xd=1.25 pu
Xq=0.75 pu

If there is a symmetric rotor, then Xd=Xq=1.25pu, for example

 

[thinker]

The ratio of starting current can be estimated as a value
inversely proportional to sub-transient reactance X", e.g
for X"=0.2 the ratio is 5.