Model/Make: Variac Transformer Model No. TDGC2-2KM

Documentation: https://variac.com/staco_variable_transformer_100_.htm

This is an autotransformer.  One end connects to the wall outlet and the socket output voltage can be varied from a small AC voltage to higher than the line voltage.  It is sometimes used for testing equipment that may have a power supply problem.

Using this thing to control an AC fan speed would be like using a nuclear reactor to boil an egg.

Logs

[amt-asset-status-list id=AMT138]