PBX1500/3500 Overview

  • Standard PADS approved chargers based upon well proven technology for UK railway applications
  • Special railway charger systems based on the PADS approved products
  • Custom variations for underground and mass transport projects
  • Rugged industrial design
  • Compliant with rail industry standards
  • Single and three phase input variations

PB Design have been supplying charger systems designed specifically for use in railway and mass transit systems for over 30 years. For railway applications the range comprises standard PADS approved charger systems and variations based on these standard PADS products that are customised to meet specific rail project needs


  • Output voltages: 24, 30, 48, 60, 110
  • Single and three phase
  • Current ratings from 2A to 300A
  • Thyristor (SCR) based for high reliability and long design life (>20 years)
  • Compatible with lead acid and nickel cadmium batteries
  • Digital meter showing voltage or current
  • Microprocessor-based alarm controller

The design of these chargers is of the constant voltage type and as with all constant potential charging systems the battery charge current will vary according to the battery demand as determined by its state of charge/discharge.

If the battery has been discharged following a mains failure the charge current on restoration of the mains would be proportionally high in the first instance and reduced thereafter as the battery recovers and its terminal voltage rises.

To safeguard the charger from such high current demand and to optimise the rating of the charger, current limiting circuitry is included within the system, due to industry requirements the level of this is application specific.

The charger characteristics change from a current limited, constant current type at low battery voltage to a variable current and constant potential type as the battery voltage recovers to its fully charged state. When fully charged the battery is maintained constantly at its float voltage level while the charge current is reduced to a level sufficient to offset system losses and maintain the battery in a fully charged condition.

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