Protection circuit for 3 phase bridge misconnection?

I would use a microcontroller.

Each phase would be connected with a potential divider, but a three-resistor potential divider. There would be a low value resistor between the analog input and ground, and an equal resistor between the analog input and +5 V (assuming a 5 V supplied microcontroller). The final resistor would be a high value resistor between the phase and the analog input. A total of 9 resistors for 3 phases.

So each phase would be measured, the peak negative voltage giving near 0 V on the analog input of the microcontroller, and the peak positive voltage giving near 5 V on the analog input.

With that, the processor can work out if all the voltages are correct and if the phase rotation is correct.

I did something very similar to check phase rotation using a PIC16F877 about 20 years ago. In that case the processor had to do a load of other stuff which is why I used a microcontroller with so many pins. There are 8 pin microcontrollers with 5 analog channels that could do what you want.

So each phase would be measured, the peak negative voltage giving near 0 V on the analog input of the microcontroller, and the peak positive voltage giving near 5 V on the analog input.

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Thanks, the phases are each 90-265VAC....(each will be same voltage but anywhere between 90-265VAC).

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.......Sorry i dont know why it put my words in quotes.