This is a Brand New Totaline Carrier/Bryant/Payne 24 volt Transformer. It has a primary voltage of 120/208/240 volts depending on which wire you hook up to. The transformer is rated at 40VA. The Part # is P201-3401 (also # 4000Y05E07K28). Thanks for looking and good luck!
Transformers are devices used in electrical circuits to change the voltage of electricity flowing in the circuit. Transformers can be used either to increase the voltage (called "step up") or decrease the voltage ("step down"). Transformers found in furnaces are "step down" transformers and usually convert 120-240 volt to 24 volt.