Reliance Electric 57C491 Automax Power Supply Unit

Reliance Electric 57C491 AutoMax Power Supply Module, designed for AutoMax DCS 5000 rack systems and built for Lorain ES281CMB enclosures with a keyed access, is a 275-watt DC power module with multiple output rails: +5 VDC at up to 30 A, ±12 VDC at 4 A, and ±15 VDC at 1 A. It accepts a nominal 120 VAC input (100–132 VAC acceptable) at up to 5 A and provides robust isolation and protection for industrial automation applications, including 1500 VAC input-to-output isolation and 600 VDC output-to-chassis isolation, plus an 8 A, 250 VAC AGC normal-blow fuse and over-voltage/over-current protection. The unit's dimensions are 11¾ inches high, 4 inches wide, and 7¾ inches deep, with a weight of about 8½ lb, and it features a hold-up time of at least 20 ms after AC input loss and a soft-start that ramps outputs smoothly on power-up. Efficiency is specified at a minimum of 70% at nominal line and full load, with regulation maintaining the ± outputs within tight tolerances. This power supply module is documented as M/N 57C491 within Reliance Electric AutoMax hardware, and its Lorain ES281CMB enclosure pairing with a keyed access aligns with its intended industrial control role.