High efficiency power supply

The needs

The power supply of decentralized network nodes (e.g. miniDSLAM, MSAN, DPU...), increasingly used for the realization of broadband telecommunications networks, led operators to search for power supply systems with suitable features.

Network devices, typically installed in street-side cabinets, require a local 48-60Vdc power supply which can be obtained from the connection to the electrical grid and the use of appropriate AC/DC converters.

To ensure the electrical safety requirements for these types of network systems and to minimize the installation, operating and maintenance costs, it’s required the use of class II AC/DC converters with overvoltage category 4 (OVC IV).

The output power required from these AC/DC converters is 420W without degrading performance up to operating temperatures of 70°C.

Another important required feature is a high efficiency to limit thermal dissipation and minimize energy waste with its consequent costs.

Even the compact dimensions and the mechanical resistance are important features, given the type of installation that are usually installed in small street side compartments.

Many AC/DC converters already present on the market rarely have all the required features, nor the specific conformations requested by the telco.

For these reasons, the SEMAR group designed a line of power supplies with features able to satisfy all the previous requirements.

The challenges

  • Double insulation (class II) and overvoltage category 4 (OVC IV) for safe use without the need for earthing (avoids periodic checks and costs) or additional protection and disconnection devices.
  • High efficiency in all load conditions, with low heat dissipation and energy costs
  • Ultra-compact dimensions for multiple devices in reduced installations spaces
  • Wide operating temperature range, useful for street side compartments exposed to sun and bad weather
  • Absence of cooling fans for maximum reliability
  • Resistance to mechanical stress (vibrations on street installations)
  • Possibility of remote control and monitoring

The realization

The PSH480HE device of the PSH series is a class II and OVC IV ADC/DC converter, suitable for telco and industrial application needs.

Its features allow to avoid the use of differential switch, of overload protections and of earth connection in systems where the converter is used, while still ensuring the level of safety and electrical protection required by telco systems regulations.

The PSH480HE device provides an adjustable output voltage in the 48-59Vdc range, with an output power of up to 480W and an energy efficiency greater than 95%.

The device is equipped with visual state indications and an output dry contact that can be activated on configurable conditions.

The functional configuration of the PSH480HE device (output voltage, current limitation, alarm signals...) and its status, statistics and historical events/alarms are accessible via a RS485 Modbus interface which can also be used for in-field firmware update.

  • Input 100-240Vac
  • Adjustable output 48-59Vdc
  • Output power 480W
  • Efficiency ≥ 95%
  • Class II, category OVC IV
  • Interface RS485 for configuration, status, statistics and events
  • Configurable output dry contact
  • DIN-rail mounting
  • Compact dimensions (85x118x118 mm)
  • Operative temperature from -20° to +70°C without performance loss
  • Cooling by air convection
  • Phoenix connectors for simple and easy connection and replacement
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