Generator Power Factor drops to 0.3 On Inductive Load.

Dear Everyone,
Good Day,

I am posting this thread to seek advice from you guys on one issue I am facing in a hospital power system. We have standby Generator and when we run the standby generator it trips the Main Distribution panel boards Main Air Circuit breaker. It happens after 18 minutes when it continuously operating some pumps and 2 chiller load almost 390KVA. I notice sometimes when the chiller is active the generator power factor drops to 0.3.
The interesting thing in Normal Supply everything is working fine and the only problem comes when system load is shifted on Generator supply.

Generator Rating 1000KVA.
Main ACB 3200A.
Pumps Load in Amps 200A
Chiller Load 700A.

Please seek your good advice.
It's presumed that this problem is "new" and has not always been occurring. If so, the quest is to or should be to discover what has changed and is causing this problem--the drop in power factor.

Is it possible that the generator exciter (the "AVR," the "voltage regulator") is not working properly, and/or the operator is not operating the generator correctly to support the inductive load?