Question about UPS

[peterfranks]

5 hours ago, Crossy said:

If the PSU fails in a way that bangs out 24V, farewell cameras. One would hope that the PSU is designed in a way that would prevent that (in reality they usually end up with the driver devices going pop resulting in zero output voltage).

That is what I worry the most about, and I would be serious p**sed off if 20K in cameras went tits up.

 

Also the XVR, which is rated 2A, is supposed to be connected to the same power supply, otherwise it would make no sense to have a UPS.

 

So can I assume that will not work with the 1.1A PTC fuses?

 

I will not distribute the power over the Cat cable, but use a separate 2 x 1 mm power cable.

 

The power supply looks decent enough built, but I have seen other power supplies with individual glass fuses.

 

 

The "bus" is the 30A output next to where the battery wires are connected

 

[Crossy]

How do you expect glass fuses to protect your cameras from over voltage? I'm really not sure what your objection is to the auto-resetting PTC fuses.

 

As I noted in an earlier post you could use 2 or 3 of the outputs in parallel to drive the XVR the PTC fuses will ensure that the current is shared equally by the outputs , or you could replace one of the PTC fuses by a 2.5A one.

 

SMPS's really don't tend to fail over-voltage, they tend to fail no-output.

 

[peterfranks]

Sorry, I overlooked your remark about putting outputs in parallel in a previous post.

 

As for the 12V protection, I assume there are 12V glass fuses?

 

My objection to the PTC is based on that you said, they are actually not real fuses, and their 72V rating.

 

Little do I know about how PTC's and power supplies work in real life, which is the main reason why I'm here.  ????, but I really appreciate the time you spent to explain it to me.

 

p.s.: I was looking for the WAI emoji, which seem to be available on about every forum in the world................except on a Thai oriented forum 

[Crossy]

7 minutes ago, peterfranks said:

As for the 12V protection, I assume there are 12V glass fuses?

 

OK, listen very carefully, I shall say this only once - Fuses do NOT that's NOT provide over-voltage protection!

 

Fuses provide over-current protection for the power supply and your wiring, they do not provide any protection whatsoever for your cameras, that is not why they are there.

 

EDIT The closest thing we have to a wai seems to be this  which is called "jap" (I know, I know).

[peterfranks]

I want to test how long the battery of my power supply lasts, so how do I create a constant 8A load?

 

Since the connections are fused at 1.1 A, I will have to put at least 8 connections in parallel.

 

Does that mean I put the positive to connector 1 and the negative to connector 8, or do I have to bridge them?

 

[Crossy]

To be honest I'd just calculate it.

 

If your battery is 7.5Ah, let's say it goes to 80% discharge so that's 6Ah available. At 8A that's 6/8 hours = 0.75 hours or 45 minutes.

 

If you want to do an actual test then you can use a resistor, the current isn't truly constant as the voltage will tail off but it's quick and simple.

 

For 8A at 12V you need a resistor of 1.5 ohms, it needs be able to dissipate at least 96Watts.

 

https://www.lazada.co.th/products/1pcs-01-ohm-05-ohm-1-ohm-15-ohm-2-ohm-3-ohm-4-ohm-5-ohm-6-ohm-8-ohm-10-ohm-12-ohm-15-ohm-20-ohm-22-ohm-30-ohm-33-ohm-50-ohm-100-ohm-1k-ohm-100w-power-aluminum-shell-wirewound-resistor-resistance-for-electronic-diy-i2277863887-s7654802870.html?

 

 

Or you could buy a true constant-current load.

 

https://www.lazada.co.th/products/180w-dc-usb-tester-app-electronic-load-lithium-battery-capacity-monitor-discharge-charge-power-checker-us-plug-i3941561207-s15205156279.html?clickTrackInfo=query%3Abattery%2Bcapacity%2Btester%3Bnid%3A3941561207%3Bsrc%3ALazadaMainSrp%3Brn%3A838718e4bd697bcc25f1b3010560efd5%3Bregion%3Ath%3Bsku%3A3941561207_TH%3Bprice%3A1299.00%3Bclient%3Adesktop%3Bsupplier_id%3A100217031603%3Basc_category_id%3A12091%3Bitem_id%3A3941561207%3Bsku_id%3A15205156279%3Bshop_id%3A3325196&search=1&spm=a2o4m.searchlist.list.i40.2df21a131f7c37

 

 

 

You need to bridge all the + terminals together and all the - terminals together to avoid tripping the fuses.

 

[sometimewoodworker]

6 hours ago, peterfranks said:

I want to test how long the battery of my power supply lasts, so how do I create a constant 8A load?

 

Since the connections are fused at 1.1 A, I will have to put at least 8 connections in parallel.

 

Does that mean I put the positive to connector 1 and the negative to connector 8, or do I have to bridge them?

 

You really should understand what you are doing 1st.

 

Once you have 8 connections in parallel and an 8A load it doesn’t matter where you connect.

 

Your problems though are that you need to create a 12V limited load that will draw 8A, this is not a trivial amount of power to draw so you will need a reasonably large water tank. You will also need to be absolutely sure of the kind of battery you have and limit the draw so the battery survives your test, running a standard SLA battery below 50% or DCSLA under 20% will reduce its lifespan significantly, running them down to 12V will produce a door stop.

 

Along with those problems is the fact that your devices will not be drawing 1A each, and that you can draw more total power from your battery if done over 20 hours than over 2 hours

You can double the rated lifetime if you only discharge to 50%, and x5 if you go to 30%

[peterfranks]

2 hours ago, sometimewoodworker said:

so you will need a reasonably large water tank.

Do you mean I risk a fire when drawing 8A?

 

2 hours ago, sometimewoodworker said:

Along with those problems is the fact that your devices will not be drawing 1A each, and that you can draw more total power from your battery if done over 20 hours than over 2 hours

There is no need to know how much total power can be drawn, as it is a UPS, so I need to know how long it will last when power goes off.

 

The battery in question is a Hitachi sealed lead acid designed for UPS.

 

I also think something is built-in the power supply to prevent the battery from over discharging, because I recall when the unit arrived, the battery measured more than 12V, but the power supply would not start up on battery.

 

So if something like that is built-in, it will most likely last much less than 45 minutes, and I may have to install a Lifepo4 battery straight away.

[sometimewoodworker]

1 hour ago, peterfranks said:

Do you mean I risk a fire when drawing 8A?

You clearly do not understand if you don’t, can’t or won’t realise why you need a place for the load to dump.

1 hour ago, peterfranks said:

There is no need to know how much total power can be drawn, as it is a UPS, so I need to know how long it will last when power goes off.

 

There you go again, you clearly have no compression of the relationship between between load drawn and time that it can be drawn. The first part of your sentence “There is no need to know how much total power can be drawn, as it is a UPS” shows the depth of your lack of knowledge. 
 

The second part “I need to know how long it will last when power goes off” is absolutely dependent on the actual load.

1 hour ago, peterfranks said:

I also think something is built-in the power supply to prevent the battery from over discharging, because I recall when the unit arrived, the battery measured more than 12V, but the power supply would not start up on battery.

Likely.

 

1 hour ago, peterfranks said:

So if something like that is built-in, it will most likely last much less than 45 minutes, and I may have to install a Lifepo4 battery straight away.

Why?

 

While I’ve spent 30 years teaching none of it was electrical theory, however there is plentiful material available for self study, incredibly much more that when I started.

 

No I am no expert nor even a semi trained electronics technician or electrician, but I do know how much I don’t know and the questions to ask to learn more.
 

You really need to get yourself some basic understanding. At the moment you don’t even know enough to ask basic questions, as it demonstrated by the ones above.

 

Once you can understand the answers to reasonable questions and phrase questions to expand your knowledge there are people here who will be able to give them. I don’t know if anyone is willing to do a remedial electrical theory course.

[peterfranks]

6 minutes ago, sometimewoodworker said:

There you go again, you clearly have no compression of the relationship between between load drawn and time that it can be drawn. The fist part of your sentence “There is no need to know how much total power can be drawn, as it is a UPS” shows the depth of your lack of knowledge. 
 

The second part “I need to know how long it will last when power goes off” is absolutely dependent on the actual load.

The actual load has been determined from the beginning of this thread. It will be around 96 Watt, more or less, and it is also not important to know the exact time up-to-the-minute.

I still don't know what a water tank has to do with this, as I doubt I can hang the resistor in a water tank.

 

I am by no means an electrical expert, and I also don't think I need to be to have a few CCTV cameras installed at my house, so I ask simple questions.

 

Installation will be done by a Thai tradesman, and yes I could completely trust on what he says, but I'm long enough in Thailand to know the consequences of that.

 

I appreciate your contributions, but maybe you could consider modifying your writing style to be a bit more polite and less insulting.

[sometimewoodworker]

43 minutes ago, peterfranks said:

The actual load has been determined from the beginning of this thread. It will be around 96 Watt, more or less

No it hasn’t. You said “I have 6 cameras which are rated 1A and a XVR which is rated 12v 2A”

 

That is not the load. That is the theoretical maximum. As yet the 96W @ 12V is the maximum, the actual load is not determined so more or less is definitely less. How much less is unknown. Few devices actually run at the maximum, some never.

 

You are wise not to trust tradesmen (Thai or of any nationality) until you check.

 

As you consider my style to be too blunt I will bow out and let others try to answer your questions 

 

TTFN

[degrub]

Here is a simple user test to determine how long the ups will allow the cameras + nvr to function. 
Get everything installed, charged up, and verified to work. Then, turn off power to the system and let the ups do its job. Start your timer. Note the duration when the system starts failing. Done.

[bluejets]

21 minutes ago, degrub said:

Here is a simple user test to determine how long the ups will allow the cameras + nvr to function. 
Get everything installed, charged up, and verified to work. Then, turn off power to the system and let the ups do its job. Start your timer. Note the duration when the system starts failing. Done.

Commonly known as "suck it and see"........rarely fails.????

[Crossy]

4 minutes ago, bluejets said:

Commonly known as "suck it and see"........rarely fails.????

 

Some years ago we were doing a "final test" on a much larger UPS system than the OP is considering (it ran an OCC - Operations Control Centre).

 

For the test the UPS was supposed to run for two hours and then fire up a diesel genset (normally the DG would start within 2 minutes) but this was a UPS run-time test.

 

Two hours on load came, and went, finally after just over 3 hours the "low battery" indicator came on and the start signal went to the diesel, followed by "arugh, arugh, arugh" from the genset. Flat battery! Panic then ensued to get the main supply back on before the UPS did actually run out of battery.

 

All was well and someone turned on the DG's battery maintainer!

 

[unheard]

2 hours ago, Crossy said:

All was well and someone turned on the DG's battery maintainer!

That's strange.

Maybe I'm talking apples and oranges...

Shouldn't the genset be maintained by conducting maintenance runs for a predetermined amount of time (30-60 mins), usually at least couple of times per month?

That schedule would keep the genset's battery from discharging.

Unless the battery itself went bad.

 

[Crossy]

12 minutes ago, unheard said:

That's strange.

Maybe I'm talking apples and oranges...

Shouldn't the genset be maintained by conducting maintenance runs for a predetermined amount of time (30-60 mins), usually at least couple of times per month?

That schedule would keep the genset's battery from discharging.

Unless the battery itself went bad.

 

Ah!

 

We weren't directly involved with the UPS and DG itself, we were providing the load (the OCC kit).

 

This was a new install, the genset hadn't been run since it was installed maybe 18 months earlier and nobody had bothered either running the beast or turning on the battery maintainer unit (I'm assuming the designer included the maintainer as he knew exactly how often the DG would be test run).

 

As is often the case everyone assumed someone else was doing it "not my job"!

 

It wasn't in Thailand, but it was in another member of ASEAN.