Here is an answer I got from a manufacturer of a $5000.00 USD multi-channel analyzer. What the instrument does is "bins" pulses and can be used to build an x-ray diffraction set-up without any bells and whistles.

It died 2x in a short time. We had full schematics, but not the ability to fix it. It did allow troubleshooting to the board level. So, the board repair was about $1000.00 USD. I suspected the failure was due to power line issues. e.g. storms and HV nearby from the SEM (Scanning Electron Microscope).

While looking over the schematic, I found ZERO circuitry for even basic power line protection and called the company.

They informed me that the device is designed to operate at 120 V +-10% 60 Hz +- (Some number) and therefore a power spike falls out of that range. You did not supply the device with the correct power, so no warranty.

I did add a trip-lite ISOBAR and we did have no problems. The warranty is worth a lot, but you HAVE to have the paperwork. We had a fried ISOBAR that had black dust on it which I suspect got hit by lightning. Trip-Lite replaced the expensive monitor with an equivalent.

The best power protection that I employed was a Tripp-Lite ISOBAR AND a ONEAC (now PowerVar conditioning transformer.

Someone decided to start buying APC surge suppressors. They were cute. There was a thermal fuse in them which if it blew would turn on the "unprotected" LED and promptly pass the surge to the equipment.

 

I totally agree with KISS about the value of the Tripp Lite Isobar, and the validity of their warranty. THAT company is certainly a model of integrity that others should follow. My experience was similar, bt I did not ask for a replacement because the lightning came in on a different cable and entered the Isobar package from the case. So it was not a failure of their device that caused my problems. They were still willing to cover my loss though. Totally impressive integrity.

 

If the device that you are using is really an adequate transformer then it will not have any problem. Some groups call their modules transformers even if they are something else, because most folks have no idea what an actual transformer is. The variac package in the pictures is certainly a real transformer device and will be fine, even if it is inconvenient to carry around.

Good to know. Thanks!