Smaller DIN-rail supply delivers up to 500W

With the new SL20.310 (24-28V/20 or 25A) Puls has released the latest version of its power supply classic, first introduced to the DIN-rail market by the Munich-based company five years ago.

With the new SL20.310 (24-28V/20 or 25A) Puls has released the latest version of its power supply classic, first introduced to the DIN-rail market by the Munich-based company five years ago.

Once again, the extremely compact three-phase power unit (150 x 124 x 121mm) is likely to prove itself an innovation driver for the market.

No fuses for primary or secondary circuits are needed and in the event of an overload it offers the option of delivering a permanent output current of up to 28A, or shutting off the power permanently - in so-called 'fuse mode'.

The three-phase wide range input (400-500V without switching) and what is undoubtedly the most comprehensive licence package on the market (including EN 60204 and CB Scheme) offer extremely simple integration worldwide.

The unit will also withstand a phase failure undamaged, even over a long period.

At high ambient temperatures or excessive loads the output power is reduced accordingly.

At the same time, at just 150mm wide with the same output power (500W), the unit is a further third smaller than its predecessor and up to 60% smaller than the units offered by the competition.

Despite the smaller dimensions Puls has succeeded - thanks to high quality electronics and thermal improvements - in increasing the MTBF even further to more than 510kh.

In addition to the potentiometer for adjusting the output voltage (24-28V), users have two extra configuration options by way of two jumpers in the base of the housing, offering easy external access.

The right jumper is used to choose between continuous-current mode and fuse mode under overload conditions.

In the continuous mode, in the event of an overload the unit delivers up to 28A output current with reduced output voltage but without shutting off, allowing it to start up heavy loads such as motors or DC/DC convertors.

In fuse mode the power unit shuts off permanently after a typical 4s overload and - just like a fuse - remains switched off until reactivated externally.

This status is displayed by a flashing red LED on the front of the housing.

The unit is reactivated if either the reset key in the base of the housing is pressed or if the input is disconnected from the power supply for at least 1min, which also enables the unit to be switched back on remotely or automatically, as required.

The internal logic identifies the overloadï status by recognising that the set output voltage can no longer be maintained.

This technology allows the unit to deliver a more reliable response than any automatic fuse.

With the left jumper the internal regulator can be switched to parallel mode; in parallel mode a gently sloping characteristic (1V difference between idle and nominal load) then ensures a reliable load distribution between all the connected units.

Because the control electronics also remain fully active in idle mode, unlike in normal cases, in parallel mode the unit will immediately compensate smoothly for load surges.

This enables up to ten SL20.310 to deliver a total output of 5kW.

As with its predecessor, the SL20.310 can also be used at ambient temperatures up to +70C (derated above +60C), is able to cope with temporary load peaks using power boost without any loss of voltage (up to 25A for approx 1min; at up to +45C on a permanent basis) and is equipped with an active switch-on current limiter which is fully operational even if the unit is hot (eg in the event of temporary power failures).

It meets the strictest category requirements of EMC Directives EN50081 (interference) EN50082 (interference immunity) in each case and is therefore suitable for home and office use.

The active transient filter even protects it against the notorious VDE pulses (VDE0160/W2, 130 V /1.3ms).

Back to top