Start with a load schedule, not a target generator model. Separate continuous loads, intermittent loads and the largest motor or transformer inrush that may occur during the operating sequence.
Confirm whether the generator is for standby, prime or continuous duty and define the acceptable voltage and frequency dip during step loading. Altitude and ambient temperature may reduce the available rating.
A useful RFQ includes the load list, starting method, voltage, frequency, duty, site conditions and required reserve. The final selection must be checked against the confirmed engine and alternator data.