Power surges / sags

There are a few companies marketing data loggers (Pico scope might be one of them) these usually connect via USB to a PC - a laptop kept topped up by its charger might be more stable on dodgy mains.

You'd probably have to construct a voltage divider to reduce the mains voltage to a level that suits the logger's input capacity, another option you could consider is mains surge suppressors, you can get a variety of types from stores like Maplin or Focus etc, the 3 main commercial types I've seen are 4 or 6 way surge protected extension blocks, maplin stock these and a 13A plug/socket module - a surge suppressor that inserts between the plug and wall socket and Lidl stores had a "blind" suppressor module that you plug in anywhere on a ring main to protect anything plugged into that ring. Its fortunately rare for mains spikes to cause damage but they often cause computer freezes or random re-booting.

Start by finding a Competent Electrician and have him check for a bad or Floating Neutral Buss, since it seems to be system-wide. This would a simple explanation for Spikes and Sags !

Yukio YANO

Any cheap pc with sound card?? Just get any small transformer, say 6 volt out, divide that by two resistors down to 0.3 volts, apply it to the line input of the sound card, and start recording the waveform.

A proper, accurate, and reliable power recorder/monitor is expensive. Call in a contractor that specializes in electric power evaluation. He can give you a proper and accurate documentation of the fault.

One thing to note, is that with UPS's, the battery life averages about

3 to 4 years. As the batteries age, they can become less stable, and not able to hold their proper charge under load. You may find that the UPS's require their batteries to be changed.

In our facility and with our clients, we change the batteries about every 2 years to have high reliability.

Jerry G.