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Circuit diagram & Help needed repairing Alfa P-3000/24 Off-Grid Inverter


timematcher

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Hi Guys,  (Mods, please move it to the right section if i am in the wrong forum section).

This post aims to request attention of those who have experience of repairing Inverters/UPS (especially Axpert/Voltronic etc)

I am looking for the circuit digram for the following inverter Alfa P-3000/24. Its a 3kva Solar-enabled pure sine wave inverter from voltronic (but I have been using only Grid power).

Voltronic Alfa P-3000 Product Url

I had the un-lucky incident of having the grid's live wire and the output of UPS live wire touching together. As a result, the circuit in the inverter got shorted and as a primary victim, the bridge rectifier T6KB60 1N10B got shorted (at least that is the one i could Identify).

So I took it out and put in a new rectifier but it got shorted again with a spark. At that time, the ground made common for both output and the input.

So I removed the common ground wire and then put a new rectifier in again, This time, I put the UPS in series. Now both the "live" as well as the "ground" terminals of the output ports from the UPS were acting as if there are are one and the same and they have live even when the UPS is not turned on.

I intend to track and troubleshoot the problem. This inverter is out of warranty now and there are very few people in the market who know how to repair it (I am having a bad luck trying to get some time slot as they claim to be burdened with other work).

My understanding is : A rectifier in the output section (which is supposed to provide charging voltage to the batteries) gets shorted only when there is some other short component in near vicinity. The only closer component is current controller UC3483AN. There are other components such as resistors and diodes( I have checked all the diodes and they seem all right) and then there is the output section .

I am looking for circuit diagram for this model Voltronic Off-grid Alfa P-3000/24 . This is locally branded as NS but internally its from voltronic power.

Also, if there is a expert fellow, who is willing to help me troubleshoot the problem, I will greatly appreciate and welcome their useful comments. I can provide more details and screenshots if needed.

Looking forward for the circuit diagram and any useful helpful comments from any expert in repairing or dealing with voltronic.

Awais

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I doubt very much that you will find a complete schematic diagram. You may find partial sketches of similar models; I'll look later to see if I can find something.

I'm amazed at the relative lack of damage fromv that short. Perhaps it confirms something I've wanted confirmed for some time: that when inverting, the output is synchronised with the grid for rapid and relatively glitch free switching to the grid should that be necessary. Do you know if it was inverting at the time, or bypassing? If bypassing, one would imagine that nothing would happen, as AC input and output would be connected anyway (though perhaps via a common mode rejection filter).

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Alas, the best I can do is this partial schematic of the DC power supply for a 5 kVA unit:

http://forums.aeva.asn.au/forums/pip4048ms-inverter_topic4332_post59548.html#59548

The UC3845 indicated is the same as the UC3843 that you have, except for the low voltage lock out (UVLO) function; the UC3845 expects at least 8.5 V compared to the 3845's 16 V. The AC_PS_OUT signal on the left is from another UC3845/3 chip operating from the AC input.

Oh, I've just noticed that I have a 1-3 kVA service manual here (likely available from this forum; check the files sections). Perhaps the rectifier is from the charger section; in this smaller inverters, they don't use the inverter backwards to charge the battery, but have a separate charger.

The attached is from Figure 3.4, page 10, of "Axpert MKS 1~3KVA 24V Service manual".

I might be able to help a little with remote diagnostics (basically wild guesses with the experience of having repaired one 5 kVA power supply to guide them) if you provide some more clues as to what part of the circuit this is. I know it's hard.

[ Edit: I know the diagram is rather fuzzy (at least click on it and use the "full size" option), but it doesn't get better with higher zoom. They have embedded an image in the PDF with poor detail settings. Not unheard of. ]

[ Edit 2: I'd check the diodes across the bridge (WTF?) as well as every other semiconductor in the area. Also check electrolytic capacitors for venting, any signs of burning; all the usual. ]

Flyback charger 3kVa.png

Edited by Coulomb
Mention fuzzy image; check semiconductors.
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There are two service manuals for the 1-3 kVA models (KS and MKS) here; click on the below to go straight there:

Thanks, @vandyh! Sometimes we do need to service our inverters ourselves. It makes them so much more valuable when we know that this sort of information is obtainable (even if hard to find at times).

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@Coulomb Thanks so much for the replies. Here are my findings so far:

There are two UF808 diodes very close to the bridge rectifier. They seem to be reporting OK but I might procure and replace these if they are cheap enough.

I found visible smoke carbon traces (indication of burning out) on two diodes both RHRP1560 (there are 4 of them but carbon was found on only two). There are 4 of them and I will get all 4. There are on the same sink at the back side of the bridge rectifier. Close vicinity. I am guessing the probably get shorted when voltage is applied as input. So I will probably replace them already.

I found MosFETs GP4063D  too. There are a total of 4 of them. I will probably take them all out and get them replaced too. There are on the same sink at the back side of the bridge rectifier. Close vicinity.
DataSheet Here: GP4063D Data Sheet link

The UC3483AN in close vicinity to the the bridge rectifier and the UF808 diodes. I consider these potential culprits and will replace them first during the course of my debugging.

 

Here is a complete list of transistors , MosFets and Diodes

MBR20200  qty 03

GP4063D qty 04

RHRP1560 qty 04

IRFB7434 Qty 04

CSD1950KCS qty 8 (these ones are further away from the main circuit and I am not sure if there are in the input portion or the output portion)

The following 02 sets of transistors are in close vicinity to each set of 4 CSD1950KCS.

2SA1020L qty 02 and 2SC2655L qty 02

There are 03 MosFETS FQA11N90 in close vicinity of the bridge rectifier.

UF808 qty 02 very close to bridge rectifier

There are 02 AT350V ICS close to the MosFETs GP4063Ds (as mentioned before)

Then there isour current controller IC UC3843AN very close to the bridge rectifier

The other prominent components are a set of 02 470uf, 500V capacitors near the bridge rectifier.

and then 04 4200uf, 35 Volt capacitors near the DC output terminals which I am guessing straighten the pulsating DC to pure DC for charging the batteries.

I will go through the manuals in detail in my attempts to further investigate and fix the problem.  I will post more updates. But i really appreciate your input if this paints any picture and gives any idea of what might be wrong.

Awais
Screenshots
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Edited by timematcher
added pictures.
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33 minutes ago, flltech said:

Were you able to fix your problem?

Attached is service manual for this model. Hope it can be helpful.

 

ALFA 2K& 3K series service manual.pdf

Hi
I was not able to solve problem on my own but I reached out to a local repair shop who fixed the problem in an hour! LOL

I wish I had gotten a hold of ALFA manual sooner maybe could have have saved me a couple of bucks LOL :)
But this manual will surely come in handy when I run into another problem again. :) So thank you so much! :) :D

The technician told me that two resistors were busted near the bridge rectifier. Further more, there was a diode busted in the output section and a couple of transistors in the output section on the heat sink. I am not sure If he was right about what he said (he could be exaggerating the problem to justify the money he took to solve the problem).

 

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One small problem is that the batteries are getting charged very quickly and are not giving a backup of more than 1 hour on:

1. 3 tube lights of 60 watt each
2. 2 ceiling fans of 60-100watts

This was noticed after charging the batteries for 3 hours straight (note: floating charge because it charged the batteries to full in 30 minutes).

Furthermore, batteries are getting charged on a floating voltage as the battery charge indicator is full. Its gets full in almost 30 minutes.

Please note that I have lead acid batteries which are water-maintainable and I had them recharged by a battery guy on a higher current (They do this because they say that UPS is not capable to charge a dead battery, the charge must be at least 50 percent or higher for UPS to pick it up).

Does this mean that batteries are faulty or does this mean that they were charged to full? 

The batteries details are:
1. Battery type is set to AGM in software
2. Battery Bulk charging maximum voltage set to 28.2
3. Max AC charging current : 30Amp
4. Battery : Phoenix XP 200 Plus
which according to this chart http://phoenixbattery.com.pk/product.php is between 120AH to 150AH. 
5. Battery voltage in series for two batteries (12VDC each) when charging: 25.2 - 26V (taken via digital multimeter)
6. Battery voltage in series for two batteries (12VDC each) when dis-charging after 3 hr charge : 24.2 V DC

I need to help figure out if the batteries are faulty (they get charged and discharged too quickly?)

Also, need to figure out if its the inverter problem so that I can figure it our myself or get it repaired whichever option is cheaper...

Thanks

Awais

 

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Turns out, one of the cells in one of the 12Voolt batteries was shorted. I have got that cell removed and a new one installed. Still testing. will upload and share the results.

I just want to make sure that UPS is supplying correct amount of voltage and current and there is no other problem in the UPS itself.

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1 hour ago, timematcher said:

Question:

How long should it take for 3kva ups to charge a 12V+12V  batteries from 70% to 100%?

How long is a piece of string? 3KVA ups probably refers to the backup power of the UPS, not how fast it charges. So it will depend on 1) charging current, 2) Ah capacity of batteries, and then you have to remember that from 70% to full is almost all done while in float charge, so it is slow and inefficient. So it could take days with some UPSes...

Strictly speaking of course, you can never get to 100%. Like the old engineering joke: Guy and Girl are standing a fixed distance apart and repeatedly halves the distance between them. An Engineer and a Mathematician are both asked whether they will ever reach each other. The Mathematician says No. The engineer says: Technically my friend is right, but they will get close enough for all practical purposes.

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Thank for your reply @plonkster. Really appreciate the detailed explanation.

I am trying to establish if its a fault in UPS or battery so that I can fix that problem. Right now I am unsure as to what exactly is problematic.

Personally, in my humble opinion, If the UPS thinks batter is charged, it will switch to floating charge... and if the battery has a problem, it will get charged (or at least appear) to get charged immediately, attaining a voltage level that puts the UPS into an illusion that battery is fully charged.

I need a second expert opinion so that I can work towards a solution.

Thanks

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  • 3 years later...
12 hours ago, Mr T said:

I have C13 blown on the charger circuit and not able to confirm the value

If you mean C13 on the fuzzy schematic diagram several posts back, I have no idea. I don't have a 24 V model, or indeed any model with that sort of power supply.

A photo of the dead component and/or its paralleled companion (if present) would help. It has to absorb high frequency pulses from the switching of the diodes.

My guesses would be

a) Same value as C52 or C62 in parallel with it (you'll need to disconnect at least one leg to measure it)

b) If it's a ceramic capacitor, about 0.1 μF to 1.0 μF, rated at at least 30 VDC

c) If it's a film capacitor, use a good quality replacement, nearly any capacitance will do, it just needs a low 100 kHz impedance and peak/pulse current rating.

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12 hours ago, Coulomb said:

If you mean C13 on the fuzzy schematic diagram several posts back, I have no idea. I don't have a 24 V model, or indeed any model with that sort of power supply.

A photo of the dead component and/or its paralleled companion (if present) would help. It has to absorb high frequency pulses from the switching of the diodes.

My guesses would be

a) Same value as C52 or C62 in parallel with it (you'll need to disconnect at least one leg to measure it)

b) If it's a ceramic capacitor, about 0.1 μF to 1.0 μF, rated at at least 30 VDC

c) If it's a film capacitor, use a good quality replacement, nearly any capacitance will do, it just needs a low 100 kHz impedance and peak/pulse current rating.

Please find attached images, I've found a image (top view only) on the web Axpert 3Kva 24v C13_4.jpg of a normal C13, then Axpert 3Kva 24v C13_1.jpg the burnt C13, Axpert 3Kva 24v C13_2.jpg where it is supposed to be, I've cleaned the pcb already and Axpert 3Kva 24v C13_3.jpg what is left of C13

Axpert 3Kva 24v C13_4.jpg

Axpert 3Kva 24v C13_1.jpg

Axpert 3Kva 24v C13_2.jpg

Axpert 3Kva 24v C13_3.jpg

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Thanks for the photos, they help a lot. Unfortunately, I can't read the value on the good part in the first photo.

It looks like you need something like this (assuming that the 30 mm you measured was the short side of the capacitor, and it's roughly twice that in length):

https://www.digikey.com.au/product-detail/en/avx-corporation/FE52N6J0506KB/478-9664-ND/5629052

The above is from Digi-Key Australia, and has 4 pins, so you'll probably need to find something similar from somewhere more convenient. This one is a 50 μF 550 VDC polypropylene metalised film capacitor, designed for "DC link, DC filtering" applications, with "low ESR" (6 mΩ). If you have a lot of trouble obtaining this part, you have the option of fitting a bunch of surface mount ceramic capacitors in parallel, in the pads provided. 

I think you need a new fan, too 😮

As a point of interest, do you have a fuse on the battery connection? Did it blow? My guess is that the capacitor failed with an internal short, and this produced a large current, but not enough to blow the battery fuse, or if it did, it was too slow to protect the capacitor, which obviously heated up quite a lot. I suspect that you were just unlucky.

So at least, that's a clue for the type of capacitor needed. If you go for surface mount replacements, make sure that these are also designed for high pulse current and/or low ESR as well. The voltage rating only needs to be at 35 V or so (a bit more than the maximum that you will ever see with the battery voltage). For these high capacitance ceramic capacitors, I think you need to operate them somewhat near their voltage rating, otherwise they have much lower capacitance, and possibly lower performance in this application.  Film capacitors don't have this problem, so a very high voltage rating is no problem for them.

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17 hours ago, Coulomb said:

Thanks for the photos, they help a lot. Unfortunately, I can't read the value on the good part in the first photo.

It looks like you need something like this (assuming that the 30 mm you measured was the short side of the capacitor, and it's roughly twice that in length):

https://www.digikey.com.au/product-detail/en/avx-corporation/FE52N6J0506KB/478-9664-ND/5629052

The above is from Digi-Key Australia, and has 4 pins, so you'll probably need to find something similar from somewhere more convenient. This one is a 50 μF 550 VDC polypropylene metalised film capacitor, designed for "DC link, DC filtering" applications, with "low ESR" (6 mΩ). If you have a lot of trouble obtaining this part, you have the option of fitting a bunch of surface mount ceramic capacitors in parallel, in the pads provided. 

I think you need a new fan, too 😮

As a point of interest, do you have a fuse on the battery connection? Did it blow? My guess is that the capacitor failed with an internal short, and this produced a large current, but not enough to blow the battery fuse, or if it did, it was too slow to protect the capacitor, which obviously heated up quite a lot. I suspect that you were just unlucky.

So at least, that's a clue for the type of capacitor needed. If you go for surface mount replacements, make sure that these are also designed for high pulse current and/or low ESR as well. The voltage rating only needs to be at 35 V or so (a bit more than the maximum that you will ever see with the battery voltage). For these high capacitance ceramic capacitors, I think you need to operate them somewhat near their voltage rating, otherwise they have much lower capacitance, and possibly lower performance in this application.  Film capacitors don't have this problem, so a very high voltage rating is no problem for them.

Hi, thanks for the info, what I could get is this MKP1848C61850JK2 from https://www.mouser.co.za/ProductDetail/Vishay-Roederstein/MKP1848C61850JK2?qs=%2Fha2pyFaduiaB6KwCqVWXme5VB04QBHq%2B%2FZrHlXH8rlPyC2aslauyA%3D%3D, from the physical dimensions the maximum capacitance is 18uF though refer to the datasheet https://www.mouser.co.za/datasheet/2/427/mkp1848cdclink-461049.pdf

Yes agree 100% with you regarding the fan, it will be a problem 

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6 hours ago, Mr T said:

Hi, thanks for the info, what I could get is this MKP1848C61850JK2 from Mouser, from the physical dimensions the maximum capacitance is 18uF though

Ah! I've just realised that the 30 mm you showed in your last photo is the height; I assumed it would be the length or width, since those are more important for getting it to fit. So 18 μF or less is fine; the main thing is that it's a DC Link capacitor and it has the correct lead spacing (is the lead spacing on the board 27.5 mm?). A smaller capacitor might fit better. As I say, the exact capacitance isn't important. It looks like you're on the right track now.

Edit: I would get the largest one in that series with the correct lead spacing and that is narrow enough to clear the transformer without having to bend the leads (which will be 5 or 6 mm long, and you don't want them long because it will add unwanted inductance and resistance). That might be as small as the 8 μF model, just going on the approximately 2:1 aspect ratio (from above) of the original.

Edited by Coulomb
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On 2020/02/10 at 2:19 AM, Coulomb said:

For these high capacitance ceramic capacitors, I think you need to operate them somewhat near their voltage rating, otherwise they have much lower capacitance, and possibly lower performance in this application.  Film capacitors don't have this problem, so a very high voltage rating is no problem for them.

Most MLCC capacitors are rated at 1V - so if you have a 10uF 25V cap, it is 10uF at 1V, and could be a lot less at 25V. I would stick to the same type of cap here. It is hard to tell without the complete schematic, but it seems like it is used as transient suppressor of some sort in this application. I don't think its absence should stop the unit from working, but looking at the carnage, it might have taken the transformer next to it out as well.

Edited by P1000
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  • 2 weeks later...
On 2020/02/09 at 10:25 PM, Mr T said:

Please find attached images, I've found a image (top view only) on the web Axpert 3Kva 24v C13_4.jpg of a normal C13, then Axpert 3Kva 24v C13_1.jpg the burnt C13, Axpert 3Kva 24v C13_2.jpg where it is supposed to be, I've cleaned the pcb already and Axpert 3Kva 24v C13_3.jpg what is left of C13

Axpert 3Kva 24v C13_4.jpg

Axpert 3Kva 24v C13_1.jpg

Axpert 3Kva 24v C13_2.jpg

Axpert 3Kva 24v C13_3.jpg

@Mr T Here you go.

Capacitor Details: 475K 350VAC

See Photo 6.jpg Zoom it a little bit and you will find the value crystal clear.

 

I hope I am not too late for the reply.

 

 

 

 

6.jpg

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While we are at the topic, Can someone post a picture of 

MPPT Module for ALFA-M3000-24  please? I need to procure it but I do not have the MPPT module anymore.

please note that I am requesting picture of the MPPT module of the M-series AFA-M3000-24. The real picture is needed so I can send it to my seller in China to procure it.

 

Thanks so much.

 

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  • 1 month later...
On 2016/09/18 at 4:36 PM, timematcher said:

Hi
I was not able to solve problem on my own but I reached out to a local repair shop who fixed the problem in an hour! LOL

I wish I had gotten a hold of ALFA manual sooner maybe could have have saved me a couple of bucks LOL :)
But this manual will surely come in handy when I run into another problem again. :) So thank you so much! :) :D

The technician told me that two resistors were busted near the bridge rectifier. Further more, there was a diode busted in the output section and a couple of transistors in the output section on the heat sink. I am not sure If he was right about what he said (he could be exaggerating the problem to justify the money he took to solve the problem).

Dear Awais,

Can you share Alfa manual at my email ID [email protected]

 

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  • 4 weeks later...

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