Typical voltage ratios are 2400:120V (20:1), 4200:120V (35:1) and 4800:120V (40:1). The PT3-2-45-332FF is rated 3300:110V, 30:1 and rated 50Hz. The PT3 model is suitable for revenue grade metering applications. econdary Terminals are No. 10-32 screws with one lock washer & flat washer. The core and coil assembly is encased in a plastic enclosure and vacuum encapsulated in polyurethane resin.