The photographs on the previous page show a typical unit and the main features of the cabinet. Other arrangements
are available to order, we can offer a high degree of customisation on this sort of equipment.
The charger section is rated continuously at 30 Deg C ambient, and is a half-controlled thyristor system for single-phase
or fully controlled thyristor for three-phase operation. A further control unit provides overvolt and alarmed shut-off of the charger
should the output voltage go over a preset limit, the output circuit being disconnected at the output contactor. A top-mounted
lamp shows whether the charger is connected and charging or shut off, it also flashes if the disconnect function has been activated.
Output smoothing is standard on all our chargers, and the units will operate without battery if required, as stand alone power supplies.
Wiring is heavy-duty flexible stranded type with hexagon-crimped copper-tube terminals onto bolted connections throughout. Because
the operating control systems are different on the three-phase units, the PCB's are wired differently but generally they are recognisably
similar to the single-phase units.
Indicators are provided for AC ON, CHARGE, INHIBIT and FAULT. The mains isolator and output control switches are all grouped on
the front panel, the AC input MCB is located inside the cabinet.
The rest of the components including the choke, capacitors, thyristor stack and heatsink are all grouped inside
the cabinet on a sub-chassis for protection. Cooling of the unit is by a fan on the thristor heatsink and convection through the cabinet.
We recommend that batteries have no more than 4 X the rated output of the charger for a fast charge, or up to 10 X the rated output for slow and
overnight charging (200AH and 500AH for a 50A output charger.)
© Prepair Ltd 1990-2006 E&OE
TECHNICAL DESCRIPTION.
The CVT552 mobile charger comprises a high-power, fully rated constant voltage charger, contained in a rugged chassis and
casing which is designed to stand up to railway use, probably the most severe test of any equipment.
CONSTRUCTION
The system is built around a 2mm sheet steel cabinet, inside which all the main components are bolted.
(We do not use anything other than threaded fasteners, and all are either stainless steel or zinc plated)
The mains charger is mounted on a substantial steel frame in the base of the unit.
AC POWER SUPPLY
The chargers are available with either single phase or three phase inputs as standard , or we can offer 110V or 415V AC inputs as
options. Note that operation at 110V input effectively more than doubles the required AC supply current compared with 240V input.
BATTERY TYPES AND CAPACITIES
The chargers will operate on any type of battery that will accept the rated output of the charger. Typically, vented Lead-Acid and Nickel-Cadmium
types are usual, but we have had specialised versions of this charger system operating on Lithium-Ion batteries in series-parallel assemblies.
CONNECTIONS.
The standard units have approximately 5 metres of 2-core 16mm sq HOFR output cable, with or without connector as required. Input connectors can be supplied, and most of the standard output connectors can be supplied to suit, or
we can design and manufacture special outdoor connectors.
TYPICAL USERS
The CVT552 series of fixed and mobile chargers are used mainly on Rail applications, and are the standard charger for the Class 66 Freight locomotive, and the Virgin Voyager
train set. Other applications have included electricity substation battery support, and underwater/subsea battery charging.
STANDARD VOLTAGES & OUTPUT CURRENTS
The chargers are available with the following standard outputs:
29V 100A
29V 200A with dual-current control (100/200A)
72V 50A (Class 66 and 67)
90V 50A
110V 50A
Dual 90/110V 50A
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