AC Motor powered directly from mains - knocks out sensors

Hello, I have an AC synchronous motor powered directly from the mains (230V 50htz). The problem is that when I switch off the motor, dc sensors invoved in the same circuitry (powered from the same power source via a power supply) switch off and reset themselves and I do not know exactly why.
I have tried isolating the motor with a low pass (50htz) filter to get rid of EMF feedback down the powerline thru to the sensors, which improves things BUT the problem still persists.
It is as if when the motor is switched off this momentarily starves the sensor of power?? Or could it be a Voltage Reflection caused by some mismatch in impedence between the motor and its power cable ??? (researched this somewhat and found it happens with AC motors) ?? Would be grateful for any suggestions of a cure. Or in particular if it is Voltage Reflection how best can this be remedied - using a diode perhaps ????
:?:

Re: AC Motor powered directly from mains - knocks out sensor

Techqs,
Are the sensors and associated circuits powered by a regulated supply? If not, this might help.
Ragards,
Kral

Re: AC Motor powered directly from mains - knocks out sensor

The sensors are powered by a switch-mode power supply which I'm told eliminates interference fairly well so I'm fairly certain the probelm isn't there. However that power supply runs off the mains 50htz supply and therefore is indirectly connected to the motor.

Re: AC Motor powered directly from mains - knocks out sensor

Techqs,
Check your ground (common) routing. Make sure that none of the motor ground curren flows through the common connection to the sensor package.
Regards,
Kral

Techqs, what forum can advice about your circuit if it is not appeared in form of schematics or unambiguous description here? Please post schematics to get answer .

Re: AC Motor powered directly from mains - knocks out sensor

Thanks for the advice so far. Will check the ground as advised. I know that the motor is grounded and it definately shares the same ground line as the sensors.
Regards,
Techqs.