NR NR/L3/SIG/11303/2J05 ISSUE 2 PDF

Introduction

Power supplies are designed to supply equipment with particular voltages derived from a main source of electricity. They can change voltage from one type to another, provide voltages which are smoothed and free from interference, or protect the equipment and the main supply from excessive voltages or currents.

The supplier of electricity is usually the local electricity company. Commonly the feed is provided by the railway organisation responsible for the fixed plant, perhaps from the traction supply. In addition, there will usually be some sort of standby in the form of generators, batteries, or a different supply source, with appropriate switching arrangements.

Power supplies are carefully designed so that the equipment they feed works correctly and safely. You should not alter anything required by the installation drawings (such as wire size or fuse rating) without reference to the design organisation through your supervisor. Record any changes on your installation drawings.