Power conditioner vs. UPS
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robbietan
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- Antipolo City
for us in the power company, voltage disturbances/abnormalities include low/high voltage, harmonic laden voltage, voltage sags and voltage blackouts (or power interruptions). conditioning devices help equipment tolerate all these disturbances, some devices more so than others.
UPS is basically a device that converts battery DC to AC supply when there is a voltage dip or power interruption. under that heading, a UPS is a conditioning device, as it basically enhances equipment tolerance to voltage sags and blackouts.
however, some UPS models are equipped with surge protectors and voltage regulators - which makes them very handy in dealing with multiple voltage supply problems.
so there you have it - power conditioners include UPS, voltage regulators, TVSS, etc
brian john
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- Leesburg, VA
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You missed a step, a UPS that is a true on line double conversion UPS. Takes AC converts through the rectifier to DC to float charge a battery (and equalize after discharges), then converts through the inverter the DC to AC, this is very good conditioning.
Another type of UPS uses a motor generator with a battery charger for the battery, the motor generator feeds the load, upon lose of power the battery feeds motor through a inverter (GUESSING ON THIS CONVERSION). Also an excellent power conditioner.
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- San Francisco Bay Area, CA, USA
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- Electrical Engineer
Not all UPS designs are what is called "double conversion" like that, some are a Power Conditioner with a battery backup and a single conversion inverter. But even many double-conversion UPS systems have a high current bypass that provides inrush current right around the inverters so that the output transistors are not damaged by high peak loads. When they do that they may not have any power conditioning, other than maybe surge arrestors on the input terminals.
Bottom line: there are no absolute universal rules on what defines a "UPS" or even a "Power Conditioner" for that matter. You should always do your due diligence:
- Know what you want to attain.
- Ask for it when going out for bids.
- Double check they are giving it to you before purchasing.
Ups
Ups
Anothing to remember is if you are using the UPS to provide "clean" power to sensitive loads that if you specify the UPS without batteries, the UPS system can only handle a fraction of the rated load as a an "inrush current" or as some manufacturers call it "impact load" there is typically a time lag (manufacture dependant usually 1 cycle) for the front end to "catch up" with the back end of a double conversion UPS typically when batteries are used they provide the "boost" to the DC bus to allow ride thru during this type of application. so if no batteries are provided and you have a large inrush load or a sudden loss and return to power and the seconday of the UPS is hit with a large load it may cause a voltage drop across the secondary of the UPS depending on the equipment and the voltage sensetivity it may be a factor, and making sure your equipment is specified to the ITIC curve would help, another solution is to provide a set of caps where the battery terminals are to provide the ride thru if 1 cycle is too long.
Ups
Anothing to remember is if you are using the UPS to provide "clean" power to sensitive loads that if you specify the UPS without batteries, the UPS system can only handle a fraction of the rated load as a an "inrush current" or as some manufacturers call it "impact load" there is typically a time lag (manufacture dependant usually 1 cycle) for the front end to "catch up" with the back end of a double conversion UPS typically when batteries are used they provide the "boost" to the DC bus to allow ride thru during this type of application. so if no batteries are provided and you have a large inrush load or a sudden loss and return to power and the seconday of the UPS is hit with a large load it may cause a voltage drop across the secondary of the UPS depending on the equipment and the voltage sensetivity it may be a factor, and making sure your equipment is specified to the ITIC curve would help, another solution is to provide a set of caps where the battery terminals are to provide the ride thru if 1 cycle is too long.
brian john
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- Leesburg, VA
I never said all were double conversion.
K8MHZ
Senior Member
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- Electrician
I have performed autopsies on old UPS units.
The small APC UPS units do nothing to protect or condition the mains power.
There is a relay that is closed from the line to the load while power is present. When the power drops, the relay switches from line feed to inverter feed. The relays are usually audible as they engage.
Going from AC to DC and back to AC again while operating in normal mode would not only be horribly inefficient, but costly to manufacture. I suspect that no consumer grade UPS employs a continuous conversion.
So long as the relay can switch in one cycle, the effect will be a seamless transfer.
The small APC UPS units do nothing to protect or condition the mains power.
There is a relay that is closed from the line to the load while power is present. When the power drops, the relay switches from line feed to inverter feed. The relays are usually audible as they engage.
Going from AC to DC and back to AC again while operating in normal mode would not only be horribly inefficient, but costly to manufacture. I suspect that no consumer grade UPS employs a continuous conversion.
So long as the relay can switch in one cycle, the effect will be a seamless transfer.
This is partially correct. However there are a lot of things that a power conditioner has no effect upon like under voltage, over voltage, frequency variations, momentary interruption, ect. To take it one step further there is no definition of what a power conditioner is. It can be as simple as a TVSS unit that will will only clean up some minor transients and nothing else.
The answer is Yes and No. Like the power conditioner there is no clear definition of what a UPS system is. UPS fall into 3 basic catagoroes:
Stand By
Line Interactive
Dual Conversion.
Stand by UPS are the cheap things sold at box stores where the load is entirely powered from the utility input. They are designed for momentary interruption to allow time for the battery and inverter to be switched on line. Pretty much worthless.
Line Interactive UPS uttility power is not converted directly into DCbut is fed directly to criticl loads through an inductor or transformer. Regulation is continiousthe the load through the use of an inverter via a static switch working in the Buck and Boost feroresonant transformers.
Dula Conversion is what has been talked about AC-DC-AC.
Both line interactive and Dual conversion will clean up any anomalies except long term interruption. Stand by UPS mostly does nothing.
glene77is
Senior Member
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- Memphis, TN
Dereck,
Your info is interesting. Good categorization of functions.
Is the Buck and Boost Ferroresonant transformer
the same as a Constant Voltage Transformer,
where the input voltage may vary maybe from 95 to 145 V
and the output voltage varies maybe from 115 to 125 V ?
The one I used was loaded down by a capacitor, had several windings.
Not exactly true. Close all your apps and just leave up a Windows desktop. then pull the computer plug. Notice how there is a pause until it goes off. most switch mode power supplies have at least a few 60hz cycles of ride through. Linear supplies do as well depending on how heavily they are loaded. The standby UPS takes advantage of this dwell time to switch the mechanical relay.
I agree they are the cheapest option but they do work surprisingly well on your basic home PC setup.
They are line interactive. The inverter can boost or buck the output for swells and swags in the line through the magnetic transformer. So In most models the regulation is tighter than what you suggested.
I agree with you that the ride through time on a single PC with most everything shut down is the only reason most of these things work. But for the most part they have no filtering or power conditioning except maybe some MOV's or SAD;s for TVSS. Couple that with very crude Modified Sine Wave Inverters just does not cut it in a commercial or business application.
My only point was to point out UPS are not created equal. :grin:
Actually a Buck and Boost and a ferroresonant are totally different in the UPS world. The Buck and Boost is a tap changing transformer that functions only to create a wider input window for the incoming power before going to battery which extends the battery life by limiting the number of transfers to battery.
A ferroresonant UPS like the old Best Power units is actually a large iron core transformer that "stores" energy in the windings to help carry the unit while the inverter starts drawing from the batteries.
These tend to have an issue with battery life due to heat from the transformer. They tend to do very well in situations where there are many relays on the load side of the unit (like fire door magnet releases which can cause a major amount of chattering in traditional UPS's due to the DC offset).
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