I have had many generator related gear issues, i have documented here in various threads in the past so will spare you the detail
Basically generators if they are overloaded, the frequency will dip. Larger sets e.g. Fair grounds you may have noticed the set cough when additional load comes on, you may see a puff of black smoke from the exhaust as the AVR linked to the engine tries to correct the speed to keep the frequency stable. If the set that your venue hires is too small or set up with Freq too low Your gears transformers will experience higher current get hot so your protection circuit may shut it down.
An example -Quote
The lower the operating frequency the more flux lines that are generated. Operating a transformer at 50Hz generates 20% more flux lines than at 60Hz. As the number of flux lines approaches the magnetic material’s limit, the heat in both the transformer’s core and its coil wires increases, and under certain circumstances, unpredictably so. This can result in a transformer that exceeds safe temperature levels. Therefore, a transformer designed to run at 50Hz will simply run cooler at 60Hz. But one designed only for 60Hz may overheat if subjected to 50Hz.