Generator calculation?

The motor when running is 3.6MW, 0.85 PF, so its MVA is

3.6MW/.85 = 4.2353 MVA

When starting, it pulls 6 times full load current, assuming that the power source is stiff enough to maintain rated voltage at the motor's terminals. (We will assume that.) So the MVA when starting is:

Starting MVA = 6 x 4.2352MVA = 25.4118 MVA

The starting PF is 0.23, so that starting MVA consists of:

Power = 25.4118MVA x 0.23 = 5.84MW

The reactive factor RF is calculated from the power factor PF as follows:

RF = (1-PF^2)^(1/2)

RF = (1-.85^2)^(1/2) = 0.5268

The motor starting reactive load is:

MVar = 25.4118MVA x RF = 25.4118MVA x 0.5268 = 13.37MVAR

The total load on the power system when the motor starts is the sum of the standing load plus the motor load:

Total load = (6+5.84)MW +(4+13.37)MVAR

= 11.84MW + 17.37MVAR

(We have assumed that the standing load and the motor load VARs have the same sign.)

Both active and reactive total power are less than the generator's rating, so the generator has the capacity to start the motor and maintain the standing load.

Generators have protection devices which allow short term overloads.

As long as the 3.6Mw motor runs up to speed with-in the time limits of the overload device, the generator is more than capable of accepting that extra load.

You do not say if the motor is direct on line start, or soft start.