Brodribb Phase Controlled Battery Chargers

Introduction

The Brodribb range of thyristor controlled battery chargers are intended to automatically float or boost charge batteries and support either continuous standing loads such as control, telecommunications or intermittent loads such as switchgear tripping, emergency lighting and engine starting.

The chargers offer a wide range of control and alarm facilities that make them suitable for unattended operation and their precisely regulated and filtered output reduces the amount of maintenance required for the battery system.

Brodribb thyristor controlled chargers are typically supplied in single phase input up to 3KVA capacity and in three phase input above 3KVA capacity.

The charger cabinets can be wall, rack or floor standing and can house the batttery, depending upon the size of the charger and specific requirements.

Brodribb chargers are designed to comply with the relevant sections of Australian Standard AS 4044 “Battery chargers for stationary batteries.” The chargers are designed and manufactured in Australia.

Technical Description : Phase controlled Chargers

Power Conversion
The chargers use reliable high voltage thyristors to provide a controlled voltage, derived from the secondary of an isolation transformer. The mains input is isolated from the output by a double wound isolation transformer conservatively designed for temperature rise and have a 3KV primary withstand voltage.

The output of the thyristor bridge is then both inductively and capacitively filtered to give both a low ripple voltage and low ripple current, which aids long battery life.

A blocking diode in the output of the charger is fitted as standard so that the battery will not backfeed into the charger and can be safely disconnected and reconnected without causing sparking. The standard blocking diode also allows easy paralleling of similar chargers

Control of the output voltage and current is by an all integrated circuit design analog phase control, provided on a compact single circuit board which is simple to replace in service. The phase controller uses block firing techniques to give the charger control circuits maximum immunity from input waveform distortion, e.g. high impedance supplies such as generators, whilst the analog design makes fault finding simple and also keeps down the cost of spares.

Three phase chargers feature a 6-pulse full control of the thyristor rectifier bridge to provide increased efficiency and very low ripple in high power applications. The fully controlled bridge provides stability over the whole load range and does not show any ‘pulsing’ at light loads.

All chargers are of the constant voltage type with a static output voltage stability of 1% of float voltage, with a load variation of +/-10%. The chargers have electronic current limiting, variable from 80% to 110% which, combined with the output inductor, enables the chargers to withstand extreme output overloads down to short circuit conditions.

AC ripple output of these chargers is less than 2% RMS/DC on resistive loadings and is typically less than 1% RMS/DC when a battery of four times the charger current capacity is connected.