Order of the Bath

The Feb 2008 issue of Which? Magazine (page 64) has a recommendation for the Sava Plug which, it is claimed, can “reduce the power a freezer uses by around 25 per cent and a fridge freezer by about 7 per cent”

This is a letter I sent to the magazine today:—

Dear Which,

I am surprised to see (Feb 2008, p64) that you recommend the Sava Plug. I have seen no independent technical review which justifies its claims. The company are cagey about how it actually works but it can be inferred that it does some Power Factor correction. This is an industrial technique which adjusts the apparent power usage (VA) to match the real power (Watts) by correcting the phase of the load. This is effective when the load is heavily inductive such as large electric motors. This is a good reference
http://en.wikipedia.org/wiki/Power_Factor_Correction

There are two problems with this in a domestic situation which make it near useless. First, the inductive load of a freezer or fridge is small compared to industrial use so little savings will be made. Secondly, and most importantly, domestic customers, unlike industrial users, are billed in KW Hours anyway so no correction of the power factor is going to make the slightest difference to them.

Yours faithfully

This entry was posted on 23 Jan 2008 at 14:25 by Rick and is filed under Miscellaneous, Technical. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.