immersun repair -no.3

[Marcus]

hello all,

Those who came here from the old place might remember i did a couple of posts on fixing a couple of immersuns that had gone bang. Well a friend & near neighbour called an said their immersun had gone 'dead' (no bang this time), so i said i'd take a look. As you might expect with it completely dead, this one turned out to be an easy fix

It's an earlier version than the other two; V2.06 (but still the later PWM type), and comparing with the other two, doesn't have the overvoltage protection cct that blew up in the 1st repair job, doesn't have common mode chokes or nearly so much filtering, and has 2*3 blue 1.5uF caps instead of the 2 5uF black caps (one of which was the cause of the failure of the overvoltage cct), and also doesn't have the little 0.5va 15v transformer(s) which i believe were the cause of the failure in the 2nd repair job.

Anyway, finding the fault:- checked live and neutral to the board - fine; as there's a small fuse for the low voltage power supplies (small round black thing next the the grey box capacitors near the mains input) that was the next test - fine. followed live and neutral to the orange 5v 1A d.c. supply that powers the control ccts (underneath the display board - (some control ccts powered via a 3.3v linear reg)) - L & N were getting there but no 5v. connected a 5v bench supply to test - immersun comes to life (pic).

ordered a new 5v supply (Vigortronix VTX-214-005-105) and fitted. All working again.

[Swwils]

Good to see these devices built around PIC24F's. Myenergy stuff is the same, they must be feeling good knowing that they can get PICs forever whilst anything developed on something newer is struggling to get stock!

[dan_b]

ImmerSun was designed and built by the company that is now Myenergi and their equivalent current product is called Eddi.

[Mr Gus]

We had a lot of immersun failures on the old forum, it caused a great deal of angst, they were widely used by members.
(especially when the company looked like disappearing)

[Marcus]

ImmerSun was designed and built by the company that is now Myenergi and their equivalent current product is called Eddi.

Coincidentally, i had a look at an eddie for the 1st time on Saturday (not to repair - just someone showing me their setup), i had a thought that there was a resemblance to the immersun.

I can't say I've looked at what sort of microcontrollers the immersuns use - as long as that bit's working i don't need to know

[Stevews]

Hello Marcus,

I did attempt to send you a PM but as I’m a new member I wasn’t authorised to do that.

I was wondering if you could shed some light on my Immersun.

I replaced the T1 transformer as that was causing the unit to display the dreaded error 8 short circuit message. Since then it displays, on occasions when solar panels are producing in excess of 4kwh or more, a error 10 - over voltage error.

I would be very grateful if you could suggest what might need to be replaced on the Immersun.

I’ve already replaced two Varistors and the Triac and as mentioned above, the T1 transformer.

Any help would be gratefully received.

Regards

Steve

[Marcus]

Hello Steve,
Hmm, I'm not familiar with that error, but if it's an overvoltage error and only occurs when the PV output is >4kw then my 1st thought is that it might not be a fault with the immersun but that the pv is actually causing the voltage on the immersun input to go too high.

Have you checked the voltage when the error occurs?

[nowty]

I have high voltage where I live, sometimes goes to 254v or even 255v and sometimes in the middle of the night with no export ! Sometimes a pain as one of my car chargers shuts down at 254v.

I regularly used to always get that over voltage error on the Immersun but I think it did over read as I thought it was supposed to shutdown at 260v. I eventually fitted a voltage reduction unit (for other reasons) and its been fine since.

[Stevews]

Hi Marcus and Nowty,

Thanks for your replies.

I should have said that I checked the input voltage with an independent tester and the results were between 244v-248v. At the same time the Immersun believed the input voltage was between 248-262v and when it exceeds 260v it displays error 10, stutters for a few seconds and then goes back to normal showing a voltage input of around 250v. Please see below the various screen shots of the Immersun readings.

It normally happens when the PV exceeds 4kw (approx 1kw to the house and the remaining 3kw+ to the Immersun) eg only when the input voltage is greater that 3kw direct to the Immersun.

I think theres a faulty component inside the Immersun that can’t read the input voltage correctly when the input exceeds 3kw but I don’t know what that component is.

Any ideas greatly appreciated

Thanks, Steve

[Marcus]

Ok, just to be clear: when you did the independent voltage test, was that on the immersion input terminals or somewhere else in the electrical installation? Are you using a digital voltage tester?

It's curious that the apparent error in voltage reading is not continuous - and only when the immersun appears to be maxxing out on diversion.

I'm still not certain wether it is a fault in the immersun or a poor connection somewhere that's allowing the voltage at the immersun terminals to momentary rise above grid voltage. If I were you i would be tempted to inspect and retighted all connections between the immersun and grid and the immersion (include checking the plug in connectors on the immersun itself), and all the connections between the inverter and grid. If the fault is reproducible, i might try connecting and old incandescent lamp to the input of the immersun to see if i could 'see' any voltage fluctuations.

If it is a fault in the immersun:-

Then, i expect there would be a resistor voltage dropper connected to a 4pin opto-isolator connecting to the input side of the immersun - possibly downstream of the common-mode choke and input inductor, but not necessarily (there are several different versions of the immersun and they don’t all have the same input arrangement). Trouble is, i don't see a fault in the input voltage detection cct causing the described fault - usually, either the resistors and opto-isolator are faulty, or they're not.

i suppose a dry solder joint on the pcb could cause an intermittent error - particularly if the board's heating up under full load.

On the original 'immersun that went bang' the fault was caused by the failure of one of the 5uF capacitors under the display board, causing voltage spikes that caused the overvoltage protection cct to keep triggering and blowing up the varistor. You say you have replaced two varistors and the triac (i only remember one varistor) - was that 'cos they blew up?