What you want is a transfer switch designed around transferring power between a mains power source and a backup generator power source rated for the voltage and current you plan to switch. Below is a 220 VAC 100 AMP transfer switch.between grid source and backup generator
I would gamble that you would not take the gamble. You nailed it.This is why I mentioned that he might just get away with it on the assumption that although the circuit for the building is rated for 100a, how often does the load reach this, if at all.
But it is still a gamble.
Some sites say it's 115a for AC-1 and 95a for AC-3If it is a AC1 load and the 100a is rated load, not necessarily the actual, or at least fluctuating, you might get away with it.
If I use two poles for phase and two poles for neutral, is that safe scenario ?This is why I mentioned that he might just get away with it on the assumption that although the circuit for the building is rated for 100a, how often does the load reach this, if at all.
But it is still a gamble.
Ok... do you think it's should safe with dry contact ?, also I use two contactor with mechanical interlock and controlled by PLC, and contactor coil plus PLC is powered 24v DC from batteryIt should, especially if you could guarantee dry contact switching.
That would be true. Though I never looked at it as to switching time and normally relied on a single set of contacts. Also, I never switched the neutral of ground lines, only the hot lines. The transfer switch I posted earlier is switching 240 VAC (phase to phase) or what we call 240 VAC split phase.I was called schneider technical services, they tell me, for wiring scheme that I was described, there is difference in time for closing and opening time for difference poles, even in one contactor, if differences per poles is not exceeds 20 milliseconds is OK, if exceeds is can burnt that contactor contacts