meter dated October 1955
Evershed & Vignoles Megger
series 2. This is
a very common and robust instrument housed in a cast metal housing
unlike the earlier series 1 range of instruments. It can be used
as a conventional insulaton tester, a conventional resistance bridge
and for the "Varley" method of line test. This simplified diagram shows
how this is accomplished. In common with other Megger models an RC
snubber is connected across the generator terminals. In this model, and
I suspect others, this comprises a 4700 ohm resistor in series with a
0.1mFD capacitor.
This instrument is one of a number given to me by Martin Harrison which belonged to his father who was a a Chartered Electrical Engineer. He collected both old electrical test equipment and due to his name (John Harrison) old clocks. Martin thought his father would have been pleased with his items been given a new home and owner.
I found the instrument to be in
working
order and accurate when tested against a range of standard resistors on
both the Bridge and Megger modes of operation. The open circuit output
on the Megger switch position was 488 volts and on the Bridge position
in the region of 20 to 30 Volts.
A lighter, more modern version (not
in my
collection) dating from the 1970s is shown below:
