Testing Inverters

[fridge doctor]

Hi Guys.

It’s that subject of Inverters again. I confess I am hopelessly lost on this subject. Give me a reciprocating single phase relay/cap start/run comp, or a straightforward 3 phase comp and I am in my own backyard… But what about Inverter comps? All this stuff about changing AC to DC and back to simulated 3Ph AC ? frequency modulation and what part do all the electronics play, and the 1500uf capacitor ? I have contacted major distributors with specific problems (compressors trying to start, or locking out) but they are only suggesting the trial and error methods of diagnosis (try a new PCB). It is not cost effective as we all know, and if we have integrity towards our customers we need positive information to provide positive results. No one seems able to explain how an inverter works, or more to the point how an engineer is supposed to test the equipment… I currently have one customer with several Mitsi inverters (3 years old ) givimg similar fault codes, the basis of which being "Fault on outdoor board/compressor fault/locked rotor" etc.. There are instances where I have heard the compressor trying to start (and failing)... The capacitors (3 x 560uf) are soldered to the outdoor board and therefore not easily checked or replaceable, and yet a few hours later the unit starts. (I stress this has not been due to a local overheat situation in which the thermatrip has operated). What can an engineer do to check ? Most of us are only mildly connected to the electronics side of refrigeration circuitry, yes we can recognise transformers, capacitors, diodes, IC's etc, but who can tell us how to easily check the boards ?

HRP, a well known distributor in the UK recently offered this advice from their tech dept. "If the comp isn't starting take the leads off and connect to a known good 3 phase motor or other Inverter compressor in order to check the board"... Surely there must be a more scientific approach than this ?

[The Viking]

In short, HRP's approach isn't bad.
Personally, I normally follow this route:

1. Disconnect the compressor (electrically)
2. Check if compressor is down to earth.
3. Check resistance across windings.
4. Restart the system (without the compressor fitted) and check the output from the inverter (the leads to the compressor, now disconnected). The important thing here is that the voltages between each phase and earth is equal, it doesn't matter what it is as long as it is roughly the same for all tree phases.

Depending on the findings from the above test, I would then proceed with:
A1. Connect the compressor to a 3 phase supply (via suitable safety devices) and test the compressor, monitoring the running current. PHASE ROTATION!!
NOTE: only for a short period, the rest of the system does not know that the compressor is running and there is a possibility to do damage.


B1. Get hold of the proper manual and check all relevant resistors / capacitors / noise filters and so on, of the inverter.
(it is normally possible to check capacitors even if they are soldered on to PCBs, just measure on the soldered pins)
B2. Try to run another 3 phase motor of equal or smaller size from the inverter or use inverter checker if available.

NOTE: Some of the latest generation VRFs utilise DC compressors, these should not be tested on 3 phase AC

[momo]

I agree: trying times with so much in the way of electronics AND unrepairable boards for the most part, even with a decent electronics workshop.

Check power supplies...
Investigating working limits on inverters, we had previously assumed that they were a solution for weak (under-rated) wiring since the compressors did not sag line voltage on start up...

However the machine is charging up capacitors for a good part of the time only on the peak of the AC wave: short time + high current => distorted wave form, add an oven, a brown out, quick cut or other mains irregularities and you get problems.

It first arose for me on a Daitsu and fortunately the customer was an ex-electrician and we resolved it amicably by testing the house supply on full load (it occured the day after the unit was installed in the evening, tourist area plenty on...)
Conclusion: protections tend to be better for inverters but don't assume them to solve bad supply probs (like you have on Cyprus? ) you will have weird errors appearing.

PS I use a lot of Mitsi's also. PM if you have comments.

PPS I like the ideas for testing boards using 3-phase motors however: WATCH the voltages some only go to 250 across phases others 400v + also with DC in charged capacitors TAKE CARE.
3 phase DC motors any ideas for testing out there?
Principle of operation for compressors?

[paul_h]

I'm a service agent for fujitsu, which used mitsi compressors and IPMs, (intelligent power module - the device that gives the compressor the three phases).
To test the IPMs, you check it's diodes. Turn the units off and wait for the capacitors to lose their charge and drop the power relay out.
You find the IPM output plug (compressor feed) and the IPM power input plug (two wires from the PCBs going to the IPM). Put a mulitmeter onto one of the IPM inputs, say multimeter red, then check across all three outputs with the multimeter black. Then reverse the leads, ie multimeter black on the IPM input wire and check the output wires with the multimeter red. Then check the other input wire to the IPM outputs in the same way.

(edit: I described that as if the IPM was seperate to the PCBs so there's connecting wires. It may be mounted on the actual PCB itself, so all you have is solder points. It still works OK putting a multimeter on the IPM chip input solder points, and compressor feed solder points on the PCB)

There's certain values to look for, but basically you'll get open circuits in one direction, and a low voltage value (about 0.4-0.5V) in the other. What you are looking for is shorts indicating one of the diodes in the IPM is stuffed, ie 0V or very very low voltage, that means a IPM fault.
Tthe fact that the unit ran OK hours later seems to suggest a compressor fault, as electronics don't normally go from not working to working, they blow and never work again.
Exceptions are bad joins and overheating - look hot spots, loose plugs and see if the IPM has adequate thermal paste and connection to the heat sink.
In your case, if it's not a bad connection it's a malfunctioning compressor.
I can say after repairing domestic inverters for 4 years, I've had a lot more compressors go wrong than inverters. A megger tester is required when working with these too, get an el cheapo from ebay. I've been sent to so many inverter units with new electronics, only to find the compressor down to earth causing the inveter to short it's diodes, and the short only shows up with a megger, not a multimeter.

[The Viking]

only to find the compressor down to earth causing the inveter to short it's diodes, and the short only shows up with a megger, not a multimeter.

Paul,
Reading the last sentence, it looks like you recommend using a megger on the electronics?

I'm sure you mean test the compressor with a megger.

Note: When you use a megger to check for short circuits (and I do agree with Paul, it's the only way to check a compressor) ensure that all PCBs are disconnected from the part you are testing.
A megger works by spiking whatever you are testing, in most cases up to 1000V (low amperage, thus not deadly for humans), PCBs and other electronic gear does not like this....

[paul_h]

Yeah sorry, I mean megger the compressor, after fully disconnecting it from the inverter.

[monkey spanners]

Get yourself one of these. the little flashy lights tell you if the inverter board if working correctly. Its made by EDC in the uk. Now all we need is someone to make a portable three phase inverter thing we can plug in a socket, hook up to the compressor and run it up manually to see if that is working.

Cheers Jon

[icecap]

Hi Paul, I think you might be able to help me with a problem I'm having at the moment. I have a 3.5kW 'DC inverter' heat pump which I installed and commissioned in the middle of May. The system serves a small 'computer server room' and operates in cooling mode only. Anyway, after approximately 11 days of operation the unit failed - the fault was down to a faulty 'IPM board' to which I fitted a replacement. The unit ran perfectly when I left site and then approximately 13 days later the second 'IPM board' failed! I reported this to the manufacturer 'Galanz' in China and they sent me 3 new replacement PCB's and they asked me to send them the 2 faulty PCB's for investigation. I fitted the second replacement 'IPM board' and this board failed after approximately 11 days!! I haven't replaced this board yet and I have fitted a mobile unit to give the customer temporary cooling whist this issue is being investigated. I have another unit which failed last week with the same fault, however this one lasted 70 days before the 'IPM board' failed. I replaced the PCB last week.

These units are installed in Manchester UK and the ambient temperature hasn't been any higher than + 18 degrees C as we are having a very poor summer. The mains supply voltage reading during commissiong and when I've replaced the 'IPM boards' has been 240V which is perfectly OK. Operating current consumption fluctuates between 1.5 amps to around 3.5 amps which is perfectly OK.

I can't put the fault down to excessive mains supply voltage. I can't put the fault down to excessive current consumption. I can't put the fault down to excessive outside ambient temperature. My feeling is that there is unit design fault to which they aren't admiting to at the moment. I am still waiting for the test report from the supplier. Any ideas??

Thanks in advance!

David

[fridge doctor]

Thanks to you all for such useful replies to my thread. I will be in the UK this coming week for a few days.... Looks like my priorities have moved to finding a Megger, and a EDC Inverter phase tester to bring back with me.... Finding bits like that here is impossible, the suppliers never even saw an AC condensate pump of any description !

Thanks again, I will post the results when I have something positive, and hopefully useful to impart.

Trevor.

[The Viking]

David,
The second unit's maintenance timer needs replacing.
If you read the manual you will find that these units requires weekly maintenance.
The timer is there so that if a maintenance visit is more than 75% overdue then the machine will stop.

Just be careful, if it goes to 500% the whole system will blow up.




P.S. No, I'm not serious, my guess is that you are right, they are having design/manufacturing issues.

[paul_h]

Hi Paul, I think you might be able to help me with a problem I'm having at the moment. I have a 3.5kW 'DC inverter' heat pump which I installed and commissioned in the middle of May. The system serves a small 'computer server room' and operates in cooling mode only. Anyway, after approximately 11 days of operation the unit failed - the fault was down to a faulty 'IPM board' to which I fitted a replacement. The unit ran perfectly when I left site and then approximately 13 days later the second 'IPM board' failed! I reported this to the manufacturer 'Galanz' in China and they sent me 3 new replacement PCB's and they asked me to send them the 2 faulty PCB's for investigation. I fitted the second replacement 'IPM board' and this board failed after approximately 11 days!! I haven't replaced this board yet and I have fitted a mobile unit to give the customer temporary cooling whist this issue is being investigated. I have another unit which failed last week with the same fault, however this one lasted 70 days before the 'IPM board' failed. I replaced the PCB last week.

These units are installed in Manchester UK and the ambient temperature hasn't been any higher than + 18 degrees C as we are having a very poor summer. The mains supply voltage reading during commissiong and when I've replaced the 'IPM boards' has been 240V which is perfectly OK. Operating current consumption fluctuates between 1.5 amps to around 3.5 amps which is perfectly OK.

I can't put the fault down to excessive mains supply voltage. I can't put the fault down to excessive current consumption. I can't put the fault down to excessive outside ambient temperature. My feeling is that there is unit design fault to which they aren't admiting to at the moment. I am still waiting for the test report from the supplier. Any ideas??

Thanks in advance!

David

I'm not familiar with the brand or how they work, as they are all different. The advice I put in this thread applies to fujitsu, and seemed relevent to this thread because the OP was posting about a mitsubishi, and I know that fujitsu used mitsubishi compressors and IPMs.
The only advice I can give you is
1)have you meggered the compressor?
2) When you say you've replaced the IPM board, is it a seperate component, or part of the control board. ie are you just replacing the IPM or the whole lot? Besides the control part, and the IPM part, the system has main voltage filtering, a diode bridge to convert to DC, a filter module which normally upscales the voltage.
Are you mounting the IPM on the heatsink with thermal paste, making sure of good contact ie no cables getting caught inbetween?
Are the refrigerant temperatures and pressures good? A faluty TX or Reversing valve can cause compressor malfunction. I know you mention cooling only, but I've yet to see anyone produce a inverter without a r/v.
Lastly, are you sure that it's even the IPM that's causing the fault?
For example the systems I'm familiar with rely in many other components to convert 240Vac into 240vdc, then 240vdc into 380vdc etc before it even gets to the IPM, then theres a lot of other components that share that power and could cause power surges that stuff up the IPM. Not knowing the system means I can't hazard a guess on whether they're just cr*p IPMs or something else is faulty and casing IPM failure.
Bad batches of circuit boards happen all the time, for example one brand I consider very good in electronics normally, (not mentioned) just sent me two faulty boards in a row. I ended up just getting out a soldering iron and replacing the faulty components on the original PCB so I could put the job behind me and move on.

edit: Also the problem with inverter compressors is that the windings sometimes can't be measured with a multimeter. EG mitsu comps used in older fujis measure 1ohm with a multimeter, but with the correct gear they are only actually .300 ohm, the average meter just doesn't have the sensitivity to read it right. You may need to get the manufacturers data and the right equipment to check the windings.

[icecap]

Thanks for your quick response Paul! There are 2 PCB's mounted on to a common heat sink ('Power Correction PCB, and the 'Module Board'. The 'Electronic Control PCB' is separate. The LED on the PCB shows an error code of 'IPM Protection' when the board has failed. The heat pump obviously does have a reversing valve but the unit is only operated in cooling mode. I haven't meggered the windings but the compressor does work satisfactorily for a period of around 12 days until the board eventually fails (as the unit is used in a server room it is swithed on all the time and maintains a room temp of around +19 degrees C). Operating pressures/temperatures are normal, refrigerant charge correct and the outdoor unit installed in a well ventilated location.

Which other components could cause power surges to the 'IPM'? Should there be a power surge protector fitted to the unit?

By the way, these are brand new units!

[icecap]

Hey Viking, That's 30 maintenance visits per year......very lucrative;-)

[icecap]

Hi John, Can you tell where you purchased the EDC unit from?

Cheers David

[Obi Wan]

Hello All,

The original question was how does an inverter compressor work?
Actually it’s very simple, or at least it is on the Daikin VRV systems. This explanation is for the Daikin VRV II inverter system. On system the inverter compressor is known as the “Reluctance DC compressor” The DC in the name is not Direct Current but Digitally Commutated. The compressor is not actually a DC motor but is designed and built on the principle of a DC motor. Hopefully I can leave the explanation of the compressor itself for now, other wise it will be a 1000 word essay.

On the wiring diagram there is are definite area where the Voltage is AC, DC and DC regenerated into an AC wave pattern. Measuring the voltage at these places will help to find where a certain problem has occurred.

I tried attached a zipped power point presentation with some animation to show the circuit but the smallest I can make it is 250KB. Send me a PM and I will mail it to you. You will need the PPT or the below will not make any sense.

Click 1,
From the mains terminals the three phase and neutral passes to the noise filter PCB A4P. The noise filter stops any unwanted noise travelling back up the power supply lines which may affect other equipment on site. Also required by the CE standard.

Click 2,
After the noise filter, L1, L2 & N are used to feed the main or control PCB. Even though the control PCB does not directly switch 400v AC it is present on this PCB. If there is no Neutral connected or you miss wired the Neutral and L2 or L3 phases, the moment the power supplied is applied this PCB will go BANG!!

Click 3,
The reason there is 400V AC present on the control PCB is to sample the L1 and L3 phase to determine the phase rotation. The phase rotation is only required for the second or third compressors which are direct-on-line. The bit marked Q1RP is the reverse phase detection circuit. If the mains phases are connected back to front you will get the fault code error U1.

Click 4,
The L1 phase is then taken through the high pressure switches (one per compressor) and provided the relay K1R on the control PCB is made, the contactor K2M is energised to start the second compressor (direct-on-line). For normal operation the DOL compressors will always start after the inverter compressor.

Click 5,
The circuit V1CP detects the loss of the 230V signal through the high pressure switches and displays the E3 error code (HPS trip)

Click 6,
Now back to the inverter compressor. From the noise filter the L2 phase is wired directly to the bridge rectifier on the inverter PCB A2P. It does not switch through the contactor K1M. If K1M fails to energise when required then you may get the error code U2 (insufficient power supply to the inverter)

Click 7
To energise the contactor K1M there is a 230V (L1 & N) feed from the noise filter PCB to the inverter PCB. When a thermostat on an indoor unit switched on, the relay K2R on the inverter will make and will energise the contactor K1M.

Click 8
When the contactor K1M is energised, 400 V AC is applied to the bridge rectifier. This means there is demand and the inverter compressor is about to start.

Click 9
The 400 V AC is converted to DC voltage (about 540 to 600V DC). The DC voltage and current at this stage is unstable or has a ripple effect. The eliminate this, the positive line is passed through the line reactor L1R (it looks a bit like a transformer). The DC current is now nice and smooth and the capacitors are ready to be charged. The DC voltage is also applied to the power transistor module.

Click 10,
The power transistors will now switch in sequence and will regenerate the DC voltage into an AC wave pattern. The faster they switch the faster the inverter compressor will travel. The output voltage can be measured with a good multi meter set to AC voltage. To read the frequency of the inverter compressor, use a multi meter with a Hz button. Set the meter to read AC Amps and put the amp clamp on one of the output cables to the inverter compressor (U,V,W) and press the Hz button. Now you should be able to read the actual Hz in real time.

Click 11,
On this compressor there is an N terminal connection. This is not a neutral connection but a feed back signal from the inverter compressor to the inverter PCB. It tells the inverter PCB the exact position of the rotor in relation to the magnetic field created by the coils within the compressor. This is critical for the operation of this compressor. It acts a bit like the traction control on a car and if this not working correctly, it’s a bit like applying a magnetic break on the rotor.

Click 12,
The outdoor fan motor is also inverter driven. The DC voltage is also directed to the fan inverter PCB.

Click 13
When the second direct-on-line compressor is required to operate the contactor K2M is energised (click 4). Note there is no overload relay. This is replaced with a Current Transformer on the L3 phase. The control PCB can detect the current consumed by the DOL compressor. If it’s too high the system will fail on E6 error code. Another reason for using the CT is to detect when there is no compressor connected to the K1M contactor. (in case of a compressor failure some people disconnect the three phase feed to the compressor) Now if there is no current consumed the unit will fail on J2 error code. This is to ensure correct oil distribution between compressors on the same unit. If a failure on a DOL compressor occurs then you have to programme it to disable in the field setting mode 2.

Click 14,
When all thermostats on indoor units switch off, the inverter compressor will also stop. To discharge the capacitors on the inverter PCB the relay K1R will make and discharge the capacitor to the neutral line.

Clicks 15,16,17,18 & 19
Shows the areas on the circuit diagram where the voltage changes from AC to DC to regenerated AC.

See I told you there is nothing to it!!!!


Obi Wan

[Brian_UK]

Regarding the EDC inverter checker, you can get them from EDC direct I believe.

Try Louise [louise@edcinternational.demon.co.uk]
at EDC, price was 45GBP + VAT (17.5%) back in March.

[The Viking]

Hopefully I can leave the explanation of the compressor itself for now, other wise it will be a 1000 word essay.

As opposed to 1711 ??


I wouldn't mind getting the PP file........

[Obi Wan]

As opposed to 1711 ??


I wouldn't mind getting the PP file........

I have a tendency to be thorough or is that I GO ON and ON

Viking send be your email address.

Obi Wan

[hendrag]

Hi i spend quite a while teaching how to fix / diagnose inverters. heres the easy tests to do.

Testing Inverters

It is best to test the inverters with the compressors disconnected especially if you expect the fault is in the compressor. But if you remove the wires from the compressor and try to run the systems a fault will be displayed:

You will need a digital multi meter with a min max function,
Turn off the power
Disconnect the compressor either from the PCB or at the compressor terminals.
Connect your meter to two of the phases (Red to blue) set your meter to record max and min voltage
Power up and Start the unit
Let the inverter start and watch the Voltage rise
Record the maximum Voltage
The inverter will stop after a few seconds and the voltage will fall to 0
Swap the leads to measure the next two phases (Red to Yellow).
Measure as before
Repeat for the last two phases Blue to Yellow.

The readings of maximum voltage should be the same for all 3 measurements if not the PWM is faulty.

If no Voltage is sent out by the PWM check whether the Capacitors are charging, you should measure 320V DC on single phase units and 600V DC on three phase units. On most of single phase units the PWM and the capacitors etc are all on the same PCB so if there is a fault the PCB will need replacing.

hope it helps

regards
hendrag

[Thermatech]

You can suggest to the customer that the Muanufacturer technical engineer is called out to site & do diagnostics test.
£500.00 to £600.00 + your attendance cost would be enough in the UK, how much in Cyprus?

But Manufacturers technical engineer will only check all inverter circuit components & then test operation of the inverter as described by engineers here.
If you know how to test all the components & measure inverter output to compressor you can do this yourself & on small splits all of the components are on one or two circuit boards so just replace the boards is what the manufacturer will recomend.

No one can be sure if the compressor is ok untill it is fully tested running in a live system.
Then if it starts or runs with excessive amps it needs be replaced because it has some mechanical fault.

A mega test of the compressor motor windings is the important test because a ground fault will cause damage to the inverter. Never try to run a compressor with a suspected motor windings ground fault, it will be an expensive mistake.

Try explaining to the customer that the compressor & inverter are designed to only operate as a pair together & that you can repair & test the inverter first but only then can you proceed to test & diagnose any possible problem with the compressor & that if it is also faulty then it will cost £XXXX to replace.
Dont forget that on VRV/VRF systems there may be some fault in the system operation which may have caused premature compressor failure & you cannot test & monitor the system to ensure correct operation untill you have the inverter & compressor fully operational. So it is usually best to advise the customer regarding this possibility.

Its like purchasing a second hand car at auction, it might look good on the auction floor but a test drive after you have payed for it might show up some major problem which could not be seen from a visual inspection.

[fridge doctor]

Thanks for all the info guys. I picked up an EDC inverter phase tester which will be pressed into service tomorrow checking 3 (small Mitsi splits) boards. Have to say (Monkey Spanners & Brian), with regard tothe EDC unit, I expected a little more than a simple pass/fail... In fact EDC's own sales pitch implies that the unit can identify more than simply - PCB OK/Compressor OK. They quote "If one or more LED's fail to light, this indicates the position of the fault" ? There was no mention of this in the instructions though... Am I missing something ? Thanks too to Hendrag, can you just clarify for me though, If I check the output (compressor) voltage across phases (as per testing 3 phase), should I be using the DC or AC scale on the meter ?

Cheers

[fridge doctor]

Report that the EDC inverter phase tester is an accurate diagnostic tool. It may look a little tacky, but it does the business. Today it correctly identified 2 failed, and 1 (brand new) working inverter boards... Which is somewhat contrary to the concensus of opinion regarding failure of boards versus failure of compressors. However, I can only say facts are facts. £45 well spent

[ozairman]

Thanks for all the info guys. I picked up an EDC inverter phase tester which will be pressed into service tomorrow checking 3 (small Mitsi splits) boards. Have to say (Monkey Spanners & Brian), with regard tothe EDC unit, I expected a little more than a simple pass/fail... In fact EDC's own sales pitch implies that the unit can identify more than simply - PCB OK/Compressor OK. They quote "If one or more LED's fail to light, this indicates the position of the fault" ? There was no mention of this in the instructions though... Am I missing something ? Thanks too to Hendrag, can you just clarify for me though, If I check the output (compressor) voltage across phases (as per testing 3 phase), should I be using the DC or AC scale on the meter ?

Cheers

Checking the output across phases works best on the AC scale of your meter.

Static testing of the IPM as PaulH has described will show up shorts quite reliably but the EDC box or Daikin's one makes it really easy to show up an IPM that is sound as far as power transistors goes but is not actually switching properly.

The lights on the EDC box basically indicate the switching of the transistors in the IPM module, The IPM has 6 transistors inside it, 3 connect each leg of the compressor (U,V,W) to the HVDC (normally marked P) and 3 connect each leg to the DC Gnd (normally marked N). The IPM switches one leg of the compressor to P and one to N for each switching sequence, ie P-U and N-V, then P-V and N-W, then P-W and N-U. One leg of the compressor is always unpowered (but is monitored by the control pcb) and as a back EMF pulse is generated in the unpowered winding the timing relationship of this pulse being received is judged against the switching signals being sent to determine if the rotor of the compressor is actually spinning and then report any "compressor rotation/location/lock" errors.

There was a really good article in Elektor Electronics last year on brushless DC motors with some good diagrams on the switching sequences. Also search for "brushless DC motor control" and "sensorless dc motor commutation" for more info on this there is a lot around.

[ozairman]

Thanks for your quick response Paul! There are 2 PCB's mounted on to a common heat sink ('Power Correction PCB, and the 'Module Board'. The 'Electronic Control PCB' is separate. The LED on the PCB shows an error code of 'IPM Protection' when the board has failed.

Above was edited for brevity.

When you say "the board has failed on IPM protection" have you actually tried resetting the unit before replacing the board? Most times "IPM Protection" means just that, the unit has shut down as the IPM module has signaled a fault condition outside it's normal operating parameters and caused it to stop. As alluded to before it's normally and overcurrent or overtemp of the IPM module. If it's due to overcurrent then you need to be looking closely at the compressor and what the refrig system is doing at the time it fails. If its an over temp things then as has been said before is the module making good thermal contact with the heatsink and is the condenser fan running correctly?

Can you see what brand of IPM module is used on the board? or is it on the circuit diagram? if so google it and get the data sheet for the device. You will then see that there is probably a FO or fault pin, see what things can trigger a fault condition and you are on your way to working out why it is happening.

I see a lot of boards get changed due to IPM faults but in reality the board is just doing what it should due to an external condition.

Cheers

[fridge doctor]

Thanks again guys, Lotsa useful information here. Current problems sorted with new boards but there will be more of course.. One more Q. Is there any difference between a PSC compressor and an Inverter compressor of the same duty. Are they wound differently, or are they one and the same?

[monkey spanners]

PSC compressor is single phase fixed speed and an inverter compressor is three phase variable speed.

[Cool100]

Obi Wan, you still have that PPP file regarding inverters?
Can you mail it to me please?

[bangoman]

WHILE CHECKIN ON SOME INSTALLATIONS MET AGEAN INVERTER WITH SPECS:
OUTDOOOR UNIT ADV 80W
RATING 27000BTU/HR
THIS WAS SUPPLYING TWO INDOOR UNITS OF SPECS;
INDOOR UNIT ONE ADV V22G E
RATING 7000BTU/HR
INDOOR UNIT TWO ADV V71G E
CAPACITY 24000BTU/HR

IM NEW IN INVERTER TECH BT SEEMS ON MAXIMUM LOAD THE OUTDOOR UNIT WONT COPE WITH DEMAND SINCE TOTAL MAX LOAD IS 31000BTUs/HR COMPARED TO OUTDOOR OUTPUT OF ONLY 24000BTUs/HR

[bangoman]

hi all I posted this question wen I hd juss arrived in Australia and was stil a freshman in terms of inverters comn from a background with no inverters but nw that i have had my fair brsuh with them I wld love to answer mi question....
the agean inverters like most inverters outdoor units they have a maximum and minimum limity in terms of capacity.they cn operate at 55% minumum capacity and 150% maximum capacity hence the uneven capacity of bth indoor n outdoor units .

[cool_tech]

gday guys can you get the edc tester is australia?

[matt.yelland]

Hi all,

Some really good reading. Could anybody share a bit of knowledge on this one please?

I have a Hitachi Unit. 3 Phase. RAS-6HRNE. 1 master and 1 slave..... My problem is that I had a 03 and 04 fault code. Tested and found the inverter 20 Amp Fuse and Compressor 20 Amp fuse blown. Tested the inverter board and the compressor. Compressor ok electrically, but the inverter board had a black mess at the back of the board. Sent the inverter board back as warrenty and orderd a new board and a compressor due to reading a few posts about changeing the compressor.

The parts came on a next day delivery. Replaced the parts and switched the unit on and found the main pcb had no power. Checked the transformer, power in but nothing out.

I took the transformer from the slave unit to allow the store to have 50% air con. Got the transformer on a next day again.

Fitted the transformer to the slave unit and couldnt get rid of the 04 fault code. Spoke to hitachi tech and found the inverter board faulty on this unit.....

Is it just bad luck or could there be a further fault? I have checked the electrical supply, all equal as far as I can tell.

Your thoughts would be appreciated?

[NDC]

Matt
NDC support full epair and testing of inverters and VSDs
Look us up@ ndc-uk.com

[cooltools]

Stick to IMI and a c17 stat its on or its off job done and very retro

[George H]

Hi Obi Wan,

I would appreciate to receive the PP file.
Thank you!

[lawrence1]

Dave,
Your problem is the brand GALANZ ,,,,worst manufacturer in China.
They made thousands of splits which sold cheaply in Aus only to have a failure rate more than 75%.I would replace it now before you spend yopu profit on service calls.
Regards
Lawrie

[arctic]

This looks really helpfull would love to have the ppt that goes with it..

[arctic]

Hey Obi Won that info you had on inverter testing looks really helpful - would i be able to get the power point that goes with it?

[Serg89]

Hi! And to me, please ...

[sunilkumarhvac]

This is a very valuable post and reply s so thanks for all