This part is a kind of semiconductor called SR540.

Function of this product has (SR520 - SR5200) SCHOTTKY BARRIER RECTIFIER.

Manufacturers : Hornby

Image and pinout :

Some of the text within the PDF file :

SR520 THRU SR5200 SCHOTTKY BARRIER RECTIFIER REVERSE VOLTAGE: FORWARD CURRENT: FEATURES · High current capability · High surge current capability · Low forward voltage drop · Exceeds environmental standards of MIL-S-19500/228 · For use in low voltage, high frequency inverters free wheeling, and porlarlity protection applications DO-201AD 20 to 200 VOLTS 5.0 AMPERE MECHANICAL DATA Case: Molded plastic, DO-201AD Epoxy: UL 94V-O rate flame retardant Lead: Axial leads, solderable per MIL-STD-202, method 208 guaranteed Polarity: Color band denotes cathode end Mounting position: Any Weight: 0.04ounce, 1.1gram Dimensions in inches and (millimeters) Maximum Ratings and Electrical Characteristics Ratings at 25℃ ambient temperature unless otherwise specified. Single phase, half wave, 60HZ, [ ... ]

SR540 PDF Datasheet Download