Hammond 187E20 20V CT 56VA Chassis Mount Power Transformer

The 187E20 delivers a 20 V center-tapped secondary at 2.8 A, a 56 VA rating, and is one of the parts in this series with a published drawing showing its test data. It belongs to the 187 series of chassis-mount, low-voltage power transformers, which run on 50/60 Hz and suit OEM engineers and panel builders who need a fixed step-down secondary with a center tap. If you need a dual 115/230 VAC primary with the same secondary, the ordering table pairs this part with the 186E20. The part page's primary-voltage attribute reads "115 / 230 VAC", while its descriptions, the 186E20 cross-reference and the ordering table place 187E20 in the 115 VAC single-primary column; confirm the primary configuration against your design before ordering.

Construction is an economical open-style channel frame for chassis mounting. Split bobbin construction removes the need for an electrostatic shield, insulation is Class B (130 °C), and temperature rise is designed not to exceed Class A for longer life. Combination solder or quick connect terminals allow either soldered leads or quick connect wiring.

In the E-size frame, the 187E20 measures 3.68 in (93 mm) long, 1.81 in (46 mm) deep not including terminals (2.19 in (56 mm) to the terminal), and 2.25 in (57 mm) high, with 3.12 in (79 mm) mounting centers. Shipping weight is 1.7 lbs (0.77 kg).

The 187E20 drawing lists acceptance data measured at 115 V, 60 Hz on terminals 2 and 4: excitation current of 81.6 mA max, a no-load secondary of 22.30 V ±2% across terminals 6 to 10 (11.15 V ±2% per half, with terminal 8 as the center tap), primary DC resistance of 10.22 ±20% and secondary DC resistance of 0.390 ±20% at 20°C. Primary-to-secondary hi-pot is 2000 V, 60 Hz, 1 sec, and the terminals are brass.

The series is hi-pot tested to 2 KV RMS, UL listed (# E207860) Type 3AH and CSA Certified. This part is listed as RoHS and REACH compliant.