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can a UPS rectifier be used as a power supply?

can a UPS rectifier be used as a power supply?

can a UPS rectifier be used as a power supply?

(OP)
Hey folks,

sorry to bother people if this is the wrong forum. I'm looking for help regarding these devices:
Link

The issue is I have an industrial laser with the requirements for 48VDC at 50 Amps power supply. I've done a fair amount of electronics work but unfortunately I dont really get the difference between the rectifier and a standard linear power supply. Is it that the rectifier adjusts its voltage for charging UPS batteries? The rectifier documentation talks about a sense lead, is this to control the voltage level?

The docs also state: "..this system will operate as a BATTERY-LESS SYSTEM and do es not require batteries to function." but I'm just getting an independent reality check.

Other question. For most rectifiers, they usually say they are -48VDC, as in "minus 48 volts". Does that mean what I think it means? Could reverse the polarity and treat the negative side as rectifier as the "positive" side of power supply to get +48?

thanks,
owen

RE: can a UPS rectifier be used as a power supply?

These units appear to be designed to supply telecommunications equipment, where the supply conventions are ground and -48V. That is: the positive terminal is at ground potential.

Modifying this could cause some problems if the positive terminal is grounded internally or internal protection functions monitor this terminal and operate to de-energize this unit should they measure some threshold above or below ground.

It is also possible that some internal components may have voltage ratings selected with its intended operation (positive terminal at ground) and changing this will unduly stress these components over time.

Is it possible to connect your load such that its positive terminal operates at ground? Of course, the load issues would be much the same as those for the supply (internal connections, protection circuits, voltage stress).

RE: can a UPS rectifier be used as a power supply?

The main difference between a standard power supply and a charger / rectifier unit is that the charger will have some means of measuring and controlling the battery charging current such that when the battery is depleted the charger will reduce its output voltage to regulate the current to some acceptable limit for the battery. A standard power supply would just throw everything it had at the battery and probably damage it.

RE: can a UPS rectifier be used as a power supply?

(OP)
Thanks people. I dont believe I could operate my equipment with the positive terminal at ground potential so i dont think I will go with this particular supply. I have found others that will probably work, so the next order of business is to see if I need to override the current reduction associated with charging batteries. Thanks for the help.

RE: can a UPS rectifier be used as a power supply?

Positive grounded 48VDC is telecommunication equipment.

RE: can a UPS rectifier be used as a power supply?

owhite,

To clarify: the rectifiers have two sets of output terminals from the common output. The terminals intended for battery connection will have a current sensor on that branch. The main output terminals may not have a current sensor, or at least if there is it will be for overload protection. If you don't connect a battery then it probably won't cause you any concern.

RE: can a UPS rectifier be used as a power supply?

I agree. The danger is in using a power supply as a battery charger, not the other way around. If the current limit effect in a battery charger will not get in your way, it should not be a problem. But it will depend on the nature of your load. If your laser needs a big slug of current to initiate, that may be an issue. But I used to provide laser power supplies for planetarium projectors and as I recall, they had current limit added to the control boards. I did not get into why, I just remember that they did.

"Will work for (the memory of) salami"

RE: can a UPS rectifier be used as a power supply?

Read the manufacturers applications specification and talk to a manufacturer tech/sales rep about your needs.

There are models available that can be used as a straight out power supply.. Some of the very old stuff required additional capacitor banks since the batteries (not there in this application) provided additional filtering..

Think of "chargers" as power supplies having additional control functions available.. Most in this category of power systems available today are switching power supply based and microprocessor controlled with lots of options in the software to configure it to operate according to your needs.. lots of things you probably won't need (temperature profile voltage control, charging profiles, etc) just turn them off in the config... Another common use of these power supplies without batteries to provide the DC for metal plating operations.

Any precision power supply (as these are) employ remote sensing (and if for some reason that wasn't wired in, would operate off of a default profile, or flag it as a critical fault and not start up). Certainly best to install it as designed.

A manufacturing tech rep could help you select a unit to meet your needs..

Alpha Technologies out of Vancouver, BC is one of the most forward thinking, advanced technology companies I've dealt with.. http://www.alpha.com/ This stuff is premium quality as it is built to demanding standards for reliability and performance. There are many others out there...

RE: can a UPS rectifier be used as a power supply?

One thing I forgot to add... I think just about all the new models out there (at least that I have worked with) have a fully isolated DC output, and can work with positive or negative ground.. and more suited to stringent applications than doing the ground connection in the charger itself... I only seen this still done in the cheaper or older designs). The more critical applications (and usually larger systems) will have a specific point where you want the single voltage to ground reference point, typically in the DC main power distribution panel. Otherwise there are going to be stray currents.

But check this key point in any prospective unit you consider..

RE: can a UPS rectifier be used as a power supply?

A battery charger is not a voltage power supply; if it's a true charger, for most battery, it operate as constant current source up to a battery voltage level and then change to constant voltage source (float voltage). Most of charger implement trickle charge at start-up when battery voltage is too low. If such function are implemented in a "rectifier" for battery charging, can't be used as voltage power supply. Or may be used if can be disabled and configured output control voltage loop (with a max current limit for protection).

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