Hammond 157G 30H 40mA Filter Choke, 400V DC Open Channel

Rated 30H at 40 ma., the 157G is an open-bracket filter choke (D.C. reactor) in the 153-159 Series for low to medium current circuits. OEM designers, repair technicians and builders of high voltage power supplies use chokes of this type for supply filtering. The 157G provides 30H at 40 ma. with 595 ohms of resistance, on the C9H frame, and its detailed part drawing adds insulation class, temperature ratings and test conditions.

The DC resistance is 595 ohms and the unit is rated for 400 V DC maximum operation, with tolerances of 15% on inductance and resistance. Inductance values are taken at the rated D.C. current and will fall slightly above it and rise below it.

The choke is built on an open bracket channel frame and vacuum impregnated with polyurethane varnish for quiet, long-life operation. Each unit is 100% Hipot tested at 1,500 VAC and supplied with leads at least 5" long. Its drawing also specifies Class B (130°C) insulation, an operating temperature of -40°C to 105°C and a storage temperature of -40°C to 85°C.

The drawing gives overall dimensions of A 3.250", B 1.615", C 1.995" and D 2.813", with a 0.030" thick channel frame and a unit weight of 1.00 lbs. The part page lists a shipping weight of 1 lbs (0.45 kg), and the 157G is RoHS and REACH compliant (UNSPSC 39121301, UPC 623980203300). The part page and series table list a 400 V DC maximum operating voltage; the part drawing marks the unit 500VDC MAX. Op. The drawing also lists a DCR test value of 588.2 ohms (±15%) at 20°C against the 595 ohm nominal.