COTS/MOTS 1200W power supplies operate in harsh environments

Ruggedised 1200W AC/DC power supplies for ground based defence applications and harsh industrial environments make up the OFD1200A series from Powerbox. 

The power supplies are in metal chassis with a baseplate for conduction cooling. The OFD1200A series can be used with a baseplate operating temperature range of -40 up to +95 degrees C. For extremely demanding applications, they have a conformal coating and are mechanically ruggedised according to the MIL-STD810H standard. The product is designed to withstand harsh transients and meet demanding EMC performance levels as required with most common defence and the more demanding industrial applications, according to the MIL-STD- 461 CE-102 and also meeting the MIL-STD-1399-300. 

The power supply operates with a wide universal input range from 85 to 305V AC with power factor correction (PFC). Covering a large range of applications, its output voltage and current can be adjusted from near zero to the maximum allowed for each model. Designed for high availability, short time to market and to meet commercial and military off the shelf (COTS/MOTS) business models. The OFD1200A is available in four output voltages of 12V, 28V, 48V and 65V and can be connected in parallel up to nine units delivering an impressive total power level of up to 9,720W.

A number of defence applications require power supplies to operate with limited or no ventilation cooling. Typical examples are electronic equipment installed in a sealed box, radio communication systems, outdoor surveillance and access control, and indoor equipment with very strict audible noise restrictions. Reliability and the cost of maintenance are also motivating systems designers not to use fans and blowers, driving interest in conduction cooling.

This cooling requires very specific building practices and the PRBX OFD1200A has been designed to guarantee optimal heat transfer from the dissipating components to the baseplate.

To cover a large range of applications, the OFD1200A operates with a wide universal input range from 85 to 305V AC (Nominal 100 to 277V AC). The unit includes a PFC with a co-efficient of 0.98/0.95 (110VAC/230VAC).

There are four versions of single output DC voltage supplies available –  12V/84A, 28V/43A, 48V/25A and 65V/18.5A. Using a high efficiency topology, typical efficiency for the 48V output unit at 230V AC input is 92 per cent.

To precisely adjust the voltage and current to suit an application the OFD1200A offers two analogue inputs, VTRM and ITRM. Using those functions, the output voltage and current can be adjusted from near zero up to the maximum specified per model. For example, the 28V output can be adjusted from near zero Volts up to 33.6V, and the output current from near zero Amps up to 43A. The output voltage can also be adjusted using the provided onboard potentiometer.

The extended trimming and control function simplifies the utilisation of the power supply in constant voltage (CV) or constant current (CC) mode, without adding external circuitry.

For applications requiring redundancy or higher power it is possible to connect up to nine units in parallel, delivering up to 9,720W in conduction cooling mode. To maintain the highest level of efficiency when operated in parallel or in redundancy-mode, optional active ORing circuitry deploying high performance FET technology (Option-O) is available on the OFD1200A28 and OFD1200A48.

For safety, the OFD1200A has an in/out isolation of 3,000V AC and in/fg of 2,000V AC. Output isolation to FG is 500V AC. The power supply includes over current protection with auto recovery, over voltage and over temperature protection.

The OFD1200A board includes easy access to auxiliary functions via on board connectors, namely: remote control, output voltage sensing, power good as well as VTRM, ITRM.

The OFD1200A has passed shock and vibration testing as specified in MIL-STD-810H and is designed to sustain high, 20G level shocks.

In its enclosed format, the OFD1200A measures 142 x 40 x 340mm (5.59 x 1.57 x 13.38 inches) and weighs 1.8kg (max).

The conduction cooling also allows the OFD1200A to be used in applications requiring a silent power solution, such as in a control room or in industrial applications where forced air ventilation is not possible due to environmental constraints. 

The OFD1200A is certified in accordance with UL62368-1 3rd edition, cUL (equivalent to CAN/CSA-C22.2 No.62368-1).

The power supply series has a full three-year warranty and conforms to the European RoHS, REACH and Low Voltage Directives. The product carries the CE, UKCA and cURus markings.

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