I have been experiencing some problems with a power supply unit failing due to transformer faults. These 230V AC input 9V DC output PSUs are installed close to an induction motor which can be from 1/2HP to 10HP depending on the installation. It's been suggested that possibly the transformers are being damaged by transients on the mains supply caused when the induction motor switches off. There is no surge suppressor or filter in the PSU.
Can anyone comment on this?
What do you see on the mains when an induction motor is switched off?
Should the motor itself be fitted with some sort of surge absorption device?
Should I add a surge arrestor to the PSU? If so, what sort of surge does it have to deal with (how long, how big?)?
Thanks - Rowan