Solved UPS does not give any DCoutput.what we will check first.

July 29, 2015 at 23:42:16
Specs: Linux
It is an exam questions. I have two options. One site of examination branch says. Converter and other says battery . please let me know the correct answer

See More: UPS does not give any DCoutput.what we will check first.

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July 30, 2015 at 00:26:43
Would it be fair to other students if we answered your exam question for you? The exam is to test your knowledge, not ours.

message edited by ijack

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July 30, 2015 at 03:32:50
✔ Best Answer
Think about it logically...

How is the UPS powered - initially; what does it provide in terms of outputs; how would you check to see what each part of the chain is producing. Are there "any" indicator lights representing various parts of the UPS?

Maybe draw a flow chart/diagram to represent the various stages/components in the UPS from mains in to whatever out? How many places could you possibly check the system's voltages etc.? (Maybe a test meter would be useful in a real time situation)?

Perhaps have a look at few UPS online or wherever to see what they have (inside/outside) and how they work?

Just guessing isn't always the best way (although sometimes it works...). Nor is asking others to simply answer a exam question for you. No harm in asking for help of course when you have a problem in real life; but first see what you can do to resolve the problem - then seek help (stating what "you" have done thus far...). All this especially if you are hoping ever to be involved in whatever field your studies are about - and here it's presumably IT related?

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July 30, 2015 at 04:54:27
I know almost nothing about uninterruptable power supplies, so I
probably can't foul up your exam, but I can ask a question: Does
the converter convert from mains AC to DC so that it can charge
the battery? Or does it convert DC from the battery to AC for
equipment to use?

Or something else that I didn't think of?

-- Jeff, in Minneapolis

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Related Solutions

July 30, 2015 at 05:07:31
Trick question: DC output to batteries? I expect AC output to the user equipment.
If no DC to batteries:
Is the AC input present and within limits
Is the pass-by switch set
Are the fuses OK

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July 30, 2015 at 08:34:24
Thanks for replying to my question.This question was in my last red seal examination,So it does not involve my ethic.I am an experience technician with over 20 years in field.It is my curiosity to find out the proper answer.My answer was battery if no DC is coming out but Exam sites sample question answers services are giving two different answers.What is the correct answer.I really appreciate your concern.

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July 30, 2015 at 11:43:21
Ok, so assuming it's not a trick question, which DC output? Output to charge the batteries or output to USB charging ports as many UPS's have those now.

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July 30, 2015 at 11:58:08
Ok,The problem is ,nothing is mentioned,weither it is DC bus ,that I can understand then it will be converter.It is in general that the UPS is not giving any DC output,What we will check first.The answer is tricky,at one sight it is converter and the other say it is battery.

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July 30, 2015 at 14:33:51

From which one sees that the DC is derived from incoming AC - via a suitable rectifying (DC generating) cct. - to charge up the battery. The battery only comes in to play/service when there is either loss of incoming AC; or a significant fall/rise in AC volts in?

From the above article one can see that although there is a design that has the battery in cct "all" the time - there are designs where the battery is "only" actively in cct. when the incoming AC fails in some way or other.

The battery o/p in the first model is "always" supplying DC to the inverter to provide the AC o/p. In the other models the battery provides DC to the inverter "only" when required.

The term converter could be applied (or perhaps misapplied) to an inverter - since an inverter does in effect "convert" DC to AC...?

Equally the term converter could be applied to the DC charger cct/module; since it too converts - in this case AC to DC...

The inverter requires DC to function - regardless of the design of the UPS. In the first model/design if there is no DC there is no AC o/p. And since the battery is always in cct . this can only occur if the battery either has failed or isn't charging.

In the other model(s) the battery is providing DC to the inverter "only" when incoming AC fails...

If the symptoms are no DC - and the UPS is the first model, and one does not apply the term "converter" to the charger cct./module, then the first place to check is the battery - as it's the interface between input AC and out AC; since it provides the required DC to the inverter/converter?

If the symptoms are no DC and the UPS is one of the other model(s), and again one does not apply the term converter to the charger cct/module, then again the first place to check is the battery - the DC source into the inverter/converter?

If however one applies the term converter to the charger cct/module then that is the first place to check - as it's the primary DC source for all models of UPS... Be they the design where the battery is always in cct. (first model); or only in active cct. when required in the other models.

It would seem that the ambiguity of the question is deliberate? Either that or poorly thought out and presented. A clear definition of terms is missing and that leads to the konphusions noted...

Overall... since the battery is the key/essential item when the UPS is called to act (when no AC incoming etc..); and the battery provides the DC required to continue an AC o/p for whatever time; presumably the battery is the first place to check?

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July 30, 2015 at 15:11:09
Thanks for describing in details.My answer was also same but the red site sample paper industrial electrician Q.13 says .it,s converter.I am truly puzzled . anyway thanks for your help.

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July 30, 2015 at 15:24:59
They need to define "converter"... No UPS gives out DC; it only applies internally generated DC as in above earlier explanation.

Also to define more clearly the nature, type and specs of the UPS in question... (See my last reference below as to why; there being more than one type of "converter"?)

And to refer to the DC/charger cct./module as a converter is, I suggest - misleading; and in my book - incorrect..

If anything the inverter which (provides the final AC o/p) is the converter...

I suspect my use of English is somewhat different to that of those at "Red Seal"; and often in the USA there are those who tend to be a little less exact/precise (even vague...?) at times with their usage and definitions etc.?

Perhaps you might (if possible) ask Red Seal to "define converter"; especially as applied within the context of a UPS?

And this product line really gives "converter" a lot of milage...

And in the above case the term is more correctly applied; to cover a host of applications and usage ?

message edited by trvlr

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July 30, 2015 at 15:34:56
Great explanation, trvlr !

So the term "converter" is nonstandard, but could actually refer to
the DC-to-AC inverter. Or it could refer to the transformer/rectifier
that converts mains AC to DC to charge the battery.

The original question might have been in error simply by saying
"DC" when it should have said "AC". In that case, I would want to
check the condition of the battery first, both because it is the item
most likely to fail and because it is the immediate power source
for the inverter, and it is generally a good idea to check the power
source first of all.

-- Jeff, in Minneapolis

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August 1, 2015 at 07:06:50
Well explained Trvir,While checking I found out that it may be DC Ups.Many Ups are in market which provide DC output .They convert AC into DC and battery as standby . normally this type of ups are used in radio stations and in industrial control systems. Thanks guys for helping.So I will go with the answer Converter.

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August 1, 2015 at 07:26:06
So the information in the original question was incomplete; if there are now two types of UPS - one that will backup/provide AC o/p and another that will backup/provide a DC o/p.

If someone failed my exam because of my answer based of the original question - I would seriously challenge it; as the question is "ambiguous" in the light of the latest UPS technology?

It's a bit like saying a car engine has stopped; and won't start again - and the fuel gauge is showing empty. What is the probable cause?

And then saying the answer is that it needs "diesel" fuel. Whereas it could have been easily have been petrol/gasoline - a not unreasonable conclusion based on the information provided, and if one one only aware of petrol engined vehicles? (Could even have been hydrogen or natural gas too...)

A life time ago when I was in the sixth form (a precursor leading to university entrance in the UK) many of the questions in The Applied Maths exam paper (for one year) were impossible to answer - based on the (incomplete) information provided (and the time available). Our Applied maths Master took a week to solve one question - partly he suggested by luck/guesswork; and most of a week to do the rest. He formally complained to the Examining Board. They acknowledged there were problems with the questions and the paper overall; but refused to allow for it. Consequently almost no-one" passed the Applied Maths part of the (then) A-level exams. Suffice to say that the next year there were no ambiguous or poorly posed/phrased questions, and none which were lacking in required information.

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August 1, 2015 at 07:40:43
Yes I would say that ,The questions are so stupid sometime .In the same series the other question was,In an offline UPS which component will not allow the spikes to reach to output AC.they give four options.Rectifier,Power transistor,Surge suppressor,Inverter. Obviously the answer is Surge suppressor,but their answer is Rectifier.They dont provide any reference book from which you can study.

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August 1, 2015 at 10:15:23
A rectifier "might" handle some spikes... but a surge protector is designed with that in mind. I wouldn't rely on a rectifier being a spike eliminator as it were... It's designed (in conjunction with a few other components) to "rectify" AC mains to provide DC...

And this article may be of interest... A while back it was considered "wise" to replace a typical low end/domestic surge protector - after one hit... And this article does cover that to some extent...

Overall it sounds as though the website to which you refer to is not all it might seem to be; I would have serious doubts about any courses etc. they offer. Quality of questions, and info provided doesn't appear to add up to much - in terms of communication; let alone actual experience (theoretical combined with real world/actual practical).

message edited by trvlr

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August 1, 2015 at 11:38:07
trvir thanks for your prompt reply.The answers are from the official exam site which are in their sample question,answer and this both questions were in my exam in the same format.Anyway thanks,we will leave the matter as it,s.

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August 1, 2015 at 15:32:00
agreed... it's a discussion that has no end - and highly doubtful that the site etc. in question will learn, change, adopt a more distinct and clearer format...

Good luck with your exams etc...

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