transformers

[dfg12345]

what does the term  VA mean  when it is on a transformer ?

[simkon]

Volt-Ampere
As a aside, the VA rating is limited by the maximum permissible current.

[Jim Banner]

VA = rated output volts x rated output amps.   Watts also equals volts x amps but with watts, the volts and amps are in phase with their peaks occurring at the same time.

Jim

[railsider]

Just a short note on terminology: *transformers* change AC (house-current) to a different (usually lower) voltage, but it remains Alternating Current. HO trains use Direct Current (DC), which requires an additional step called *rectification8 to convert AC to DC.

The wrong kind of electricity will burn out motors and solid-statae boards, so it is important.

Generally, we use *transformer* to mean the low-voltage supply for O-scale ("Lionel") trains, and *power supply* for the DC supply on HO pikes. As a sidelight, most HO power supplies also have a pair of connections for AC, about 16 volts, to run accessories and lighting. Lights will run on AC or DC, as long as the voltage is correct, and most accessories, like crossing gates or motorized gadgets, are designed for 16V-AC.

Check labels and instructions carefully before you connect something, so you don't create a problem.

Railsider

[Jim Banner]

Even better for running dc trains is a "power pack."  This contains a dc power supply plus a speed controller plus a direction switch.  With some, the ac or dc power supply is a separate piece that plugs into a control box, often referred to as a "cab" or a "throttle," that contains the speed controller and direction switch.  The Bachmann 44212, which they call a Power Pack and Speed Controller, is an example of a two piece unit.  In the photo, the throttle (speed control and direction switch) is at left and the power supply transformer is at the right.  In addition to dc outputs for the tracks, the throttle also has ac outputs for accessories.



Jim