Hi,

Can anyone tell me the advantages and dissadvantages of the variable transformer?

 

Advantage it's variable
Disadvantage cost

 

As for a serviceman the variable transformer is a useful piece of equipment , used for troubleshooting, that is you can apply a lower voltage to check amplifiers TVs etc . I dont know you use a variable trans. where a fixed voltage is required.

 

Disadvantage: variable transformers are usually autotransformers and the secondary is not isolated from the power line.

Ken

 

Another deadly consequence of the auto transformer is the swapped (wrong) connection of LIVE and NEUTRAL connection to the primary.

The auto transformer works as usual and a lamp dims down as expected to zero when user turned down the auto-transformer, not knowing now both the connection wires to the lamp are at LIVE level.

This false sense of "lack of voltage" had killed many. Take great care.