110v site trannys

[Steve]

I understand these provide 2 phases at 55v, but what is the third wire for? Is it earth or neutral or both? How is this connected in the tranny?

And does anyone take any notice of the 10 minute duty cycle of the transformer?

(We hired a floor sander with a 110v transformer. apparently these are now discontinued and the majority of floor sanders are 240v)

 

[Diyisfun]

(We hired a floor sander with a 110v transformer. apparently these are now discontinued and the majority of floor sanders are 240v)

Not a lot of good if the site only has 110v

 

[Steve]

(We hired a floor sander with a 110v transformer. apparently these are now discontinued and the majority of floor sanders are 240v)

Not a lot of good if the site only has 110v

but is there any need to sand floors on a building site?

 

[BJS_Spark]

They are 240V single winding primary and two 55V secondary windings connected in series. The outside of the two series windings gives you 110V and the third wire is connected to the centre and is the earth for the output. Hence CTE or 'centre tapped earth' and you can now only receive a shock of 55V to earth on the output.
Also note the input and output earth are separated and the insulation between primary and secondary is very good.

 

[Spark123]

IIRC there is also normally an earthed screen between the primary and secondary coil. I think almost all tools are available in 110v, just depends who you buy from. As crafty noticed there is a continuous and a tool rating on portable tool transformers, the transformer can only handle the tool current rating for a short period and then it requires an off period too cool down (not much use if you've got a lot of grinding to do). The continuous rating is suited to site lighting i.e. a continuous load.