UnderVoltage Protection

As if loadshedding was not enough the WAPDA people have started to make the voltage dance too ( i mean fluctuate). For some days now the power voltage in our area is fluctuating and quite often there is undervoltage. What I want to ask is that does some device, other than stabilizer, exist which can automatically switch the power off in case of undervoltage (as is the case with surge suppressors in overvoltage situations)?

Also can anyone guide me about some good quality stabilizers (i mean which companies)?