Hammond 166M25 25V C.T. 3A 75VA Power Transformer

The 166M25 is a low voltage/filament power transformer from the 166 Series, rated 75 VA with a 115V 60 Hz. primary and a 25 V center-tapped (C.T.) secondary rated 3 A RMS. It is built for OEM engineers, panel builders and repair technicians who need an open style, channel bracket, two hole chassis mount transformer to derive a low AC voltage inside equipment. The 166M25 supplies 25 V C.T. at 3 A (75 VA) from a 115V 60 Hz primary, sharing its 4.03 in (102 mm) A dimension with the 166M24 frame size in the series table.

Construction follows the 166 Series design: a dual bobbin winding arrangement, so no electrostatic shield is required, and Class B insulation (130 °C) for extra protection, with the design UL listed as Class A (105 °C). Each unit is Hi-Pot tested at 2,000V RMS. Leads are a minimum of 6 in long. The drawing schematic shows black primary leads, green secondary leads and a green/yellow center tap.

Overall dimensions from the series ordering table are A 4.03 in (102 mm), B 2.25 in (57 mm) and C 2.63 in (67 mm), with a D dimension of 3.56 in (90 mm) and 0.19 in (5 mm) mounting holes (mounting reference C). The shipping weight is 2.5 lbs (1.13 kg). The part drawing gives the mounting hole size as 0.187 in / 4.7 mm width-wise.

The 166 Series is UL listed and CSA certified, and the 166M25 is marked RoHS compliant and REACH compliant. Identifiers include UPC 623980219011 and UNSPSC 39121301. If you need 117/234V or 50/60 Hz operation or dual secondaries, the manufacturer points to its 266 Series instead.