CVT552 and CVT552/3 High-Power Chargers

The Prepair CVT552/3 high power chargers are designed to be used for charging of very large capacity or very high voltage batteries in specialised research and offshore applications, where higher than usual output power is required. The chargers are designed for use indoors only, and have either a fully ventilated cabinet or are supplied in open-frame configuration for installation in customer's own enclosure. Continuous-load standby is also covered, with a battery system online at the same time, making a DC UPS system.

The photographs on the previous pages show a unit manufactured in 2004/5. This had an output of over 100kW DC, and was a one-off built for a specialist research application.


The CVT552 series chargers comprise a high-power, fully rated constant voltage charger, built in a steel framework/casing which is designed to be floor mounted in a permanent installation. Fixing holes are provided and cable access is to DIN rail mounted terminal blocks.

The charger section is rated continuously at 30 Deg C ambient, and is a fully-controlled thyristor system for three-phase operation. Single phase operation is possible up to 40kW where 3-phase supplies are not available.

The chargers have various control operation options such as Boost and Float settings, and with this latest system we were able to develop additional control functions that would interface with external PLC equipment. All settings are adjustable.

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.

Indicators are provided for AC ON, CHARGE, INHIBIT, FAULT, plus BOOST and FLOAT if fitted. Mains isolator and output control switches are provided, and input phase detection and failure monitoring is usually provided, interlocked to the start-up sequencing of the system.


The system is built around a box-section steel frame, with 3mm sheet steel chassis, to 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 main components including the transformer, choke, capacitors, thyristor stack and heatsink are all grouped inside the main chassis for protection, and the whole assembly is covered by a 2mm sheet steel body and cover. All parts are rated for long and continuous operation and have some reserve in hand over and above their continuous rating requirements.


All high-power chargers use 415/440V 3-phase supplies, but we can supply single-phase up to about 40kW. High-voltage single-phase supplies can be a good alternative, and we have supplied chargers with 440/660V input voltage ranges.


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, most applications comprise these battery types. The charger will also charge NIFE and Lithium-Ion batteries of suitable voltages and capacities.

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 (40AH and 100AH for a 10A output charger for example.)


The standard units have internal DIN rail terminals. Alarm functions are provided for external telemetry.


CVT552 units are in service in the UK for various utilities and users. The voltage ranges available are shown below, plus we are able to offer a customised output voltage and current range for OEM customers.


The chargers are available with the following standard outputs:

Any output voltage, any output current up to 100kW total output power.

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