100A power cabinet dual power switch box for fire fan water pump control ATS  panel 
Features:
1) Provided with such protective functions as checking two sources of voltage at 
the same time, protection when any one phase or one phase above experiences 
under- or over-voltage, guide phase

2) When two sources have abnormal or faulty tripping (overload, short circuit), 
the controller won't send out the order to realize the protective function of 
reopening and closing

3) Four working modes: automatic control, common source (power supply I), 
standby power supply (power supply II), breaking electricity (re-tripping

4) When the working mode is in the automatic control state, it has two 
self-throw no self-recover, self-throw, and self-recover functions:

a) Self-throw non-self recover: when the device enters the working state, power 
supply I automatically throws into supplying electricity; when power supply I 
has an abnormity, it will automatically transfer to power supply II; when power 
supply I recovers, it doesn't transfer until power supply II has an abnormity, 
then it will automatically transfer to power supply

b) Self-throw and self-recover: when the device enters the working state, the 
common source throws into supplying electricity; when power supply has an 
abnormity, it will automatically transfer to standby power supply; when common 
power supply recovers, it will automatically recover common power supply; but 
when the standby power supply has an abnormity, the controller will emit an 
alarm sound