Product category:
AC/DC Power Supplies
News Release from: Puls UK | Subject: SL10.300
Edited by the Electronicstalk Editorial
Team on 07 December 2001
Feature-packed three-phase PSU at no
cost penalty
Puls has launched a compact three-phase 240W standard power unit (10A at 24-28V DC) with a wide range of novel features, yet costing no more than the corresponding single-phase unit.
Puls has launched a compact three-phase 240W standard power unit capable of supplying 10A at 24-28V DC with a wide range of novel features, yet costing no more than the corresponding single-phase unit For example the unit needs no fuses on the primary or secondary side and provides for unrestricted two-phase use; the switchable control response offers a novel fuse mode in the event of an overload as well as reliable load distribution and stabilisation in parallel mode
This article was originally published on Electronicstalk on 10 Nov 2000 at 8.00am (UK)
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Power supply 40% smaller than corresponding units
The SL10.300 from PULS is currently the smallest 240W 3 phase power supply unit available on the market, at about 40% smaller than corresponding units of its class
DIN-rail supplies have voltage drops covered
The latest addition to the Dimension range of DIN-rail power supplies from Puls offers an answer to the age-old problem of the voltage drop inherent in longer cables.
Overload behaviour has been one of the focal points of developments by Puls for a number of years.
It was actually three years ago that Puls initiated the current trend which is moving away from the hiccup mode to continuous current in the event of an overload.
The Munich-based firm recognised that the hiccup mode, in which the power unit temporarily switches off and then attempts a restart at regular intervals every couple of seconds, poses problems in practice: the current surges that occur during the attempted restarts create an unnecessary load on the connected consumers; even more; in drive units they represent a potential injury hazard.
Further reading
Miniature supplies on the DIN rail
The ML15 range of DIN-rail power supplies offers a choice of 5, 12 and 24V DC single outputs in a tiny 22.5 x 75 x 91mm housing.
Supplies cut the cost of DIN-rail power
The C-Dimension Series of DIN-rail power supplies are considerably lower in cost than standard units, but with only minor reductions in functionality.
DIN-rail supplies come with conformal coating
Coating provides higher operational safety and reliability in a number of installation environments.
Secondly, the short current surges are insufficient to trigger a secondary fuse.
And specific loads such as motors, high capacities or DC/DC convertors require a significantly oversized power unit with hiccup response to start them.
These loads quickly consume twice or more their nominal current for start-up.
If the power unit size is geared to the nominal current it is subject to an overload when starting up and normally switches off immediately, consequently these type of loads do not actually get going.
That is why the company introduced the Puls-Overload-Design: in the event of an overload the power unit delivers up to 1.5 to 1.8 times its nominal current, with the output voltage being reduced as the current increases.
This enables even heavy loads to be started up without the need for costly, oversized units and, if necessary, the user can employ a secondary fuse in order to securely switch off the load in the event of an overload - a response which has been met with enthusiasm by users.
With the SL10.300 Puls reckons it is now meeting the demands of users to even greater effect: the overload behaviour can be switched to the so-called fuse mode via a jumper which is externally accessible.
In the event of an overload (ie if the nominal output voltage can no longer be sustained) the unit switches off the output completely after approximately 5s and displays this status by way of a flashing LED.
To reactivate the output either the reset button on the front of the unit has to be pressed or the unit separated from the power supply for about 1min.
Thanks to this fuse mode many users now no longer need the secondary fuse - particularly as the electronic fuse operates with considerably greater precision and is therefore easier to calculate (and more reliable) than standard thermomagnetic automatic fuses.
An additional secondary fuse is only required if the shutoff threshold of approximately 12.5 or 14 A (at 28 or 24V and 25C ambient temperature) is too high for the connected loads or the overload cutoff after 5s occurs too late.
This 5s delay was selected so that the power unit can also cope with the above mentioned slower loads which occur quite frequently particularly in the DIN rail area.
Moreover, this perfectly corresponds with the delay that also occurs in automatic fuses (and in this context widely disperses).
It is only when the current reaches more than 2-3 times the fuse value through an automatic fuse with the fast Z characteristic, that it is actually triggered in fractions of a second.
The SL10.300 is also internally fused on the primary side - a rare feature in three-phase units.
This means that the unit no longer needs any external fuse on the primary side, this may only be necessary in order to protect the power supply cable or for other parallel loads if these do not have any internal fuses.
The input has another new feature which has a significant practical importance: in addition to the three-phase operation, two-phase operation is also fully specified, ie for the very first time a standard power unit also provides for continuous, unrestricted two-phase operation under full load.
In addition, during test measurements the unit demonstrated an unusual tolerance of power supply fluctuations and phase shifts between the three phases when used in problematic networks.
Where other units fail, perhaps because the phase shift causes the voltage between two input terminals to exceed or fall below the specific limits, the Puls unit continues working.
This makes it ideal as an export product to areas such as Eastern Europe with quite "unpredictable".
With its 250W output capacity, the SL10.300 is positioned in the medium output range.
However, to accommodate multiple units in the same system, the unit features a parallel mode for higher-power applications.
For parallel applications the characteristic curve can be switched to be slightly "softer" (1V voltage difference between no load and full load) which ensures that all power units switched in parallel evenly distribute the load between them.
In addition, in the event of minimal capacity utilisation the power units do not go into so-called sleep mode: the control electronics remain fully active with no load.
As a result, if there is a sudden load surge each SL10.300 temporarily takes up its share of the load in the parallel grouping so that even this kind of load surge is evened out immediately and smoothly.
Up to five SL10.300s can be connected in parallel in this way, allowing virtually any application worldwide between 0 and 1250W can be covered with just one single power unit model held in stock.
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