Siemens MT0050M Control Power Transformer. Siemens Control Power Transformer, Class MT, 240 x 480 VAC Primary, 120 x 240 VAC Secondary, 50 VA Power, 50/60 Hz Frequency, 1 ph, Screw Connection, Surface Mounting, Open Enclosure, -4 to 104 deg F, 2.79 in H x 3 in W x 3.41 in D Dimensions. Additional Description: SIEM-MT0050M CONTROL TRANSFORMER,50VA,240/480-120/240. Catalog Description: Control Power Transformer, 50va, PRI 240x480v, SEC 120x240v, Domestic.