First you need to find the primary winding, probably the two black wires, the winding should be the innermost one.
Do a continuity test to see which windings are connected or separate from each other.
Apply 120v to it and check the voltage on all the other windings.
The VA rating of the transformer is basically a result of total core size of the transformer and the current capability of the windings.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.