Inverter Electronics Question...Jerry?

[NJT5047]

Looking for information on general functions of a Xantrex Inverter.
My Xantrex DR2424 took a dump.  The pass-thru mode doesn't work. 
Turn on the charge mode and it charges for a few minutes and then goes into "invert" mode and runs the batteries totally flat. 
I disassembled the unit enough to get at the AC board that has a Deltron 375-3PD relay mounted on it. 
The Deltron looks to me as though it should go to "NC" mode for the AC pass-thru...does this sound correct?
The problem might be related to my leaving the inverter hot to the batteries for years.   
I turned it off at the remote, but that doesn't completely turn the unit off. 
When the batteries are taken out of the circuit with the inverter master, the unit clicks. 
I cannot find any repair information on a DR2424. 
I would guess that some components are the same in most Xantrex units..or at least they function in the same way.
My question:  does the relay default to NC AC pass-thru mode when there's no battery power?
The unit has rarely been used for an inverter, but it has a good many hours charging batteries. 
It isn't worth sending back...it's a discontinued unit.  But there are plenty of them around...for $1000 bucks.
I found the relay on Deltrol Controls website.  http://www.deltrol-controls.com/files/rel375.pdf
Any thoughts on this would be appreciated! 

JR

[gumpy]

Hmmm..  I have a trace sw4024 and I notice 2 things with your post.... 

First, I don't think my inverter will work without batteries connected. Maybe I misread your post.

Second, I think the transfer relay is N.O., and closes when good AC is detected.

craig

[Sean]

Looking for information on general functions of a Xantrex Inverter.

You should start by downloading the user manual, if you don't already have one.  Many of your questions will be answered there.  You can find it here:
http://www.xantrex.com/support/docdisplayarchive.asp
(scroll down to DR series, then click the download button on the far right).

I downloaded the manual to answer the rest of your post:

My Xantrex DR2424 took a dump.  The pass-thru mode doesn't work. 
Turn on the charge mode and it charges for a few minutes and then goes into "invert" mode and runs the batteries totally flat.

Make certain you have properly set the AC voltage range as described on pages 3-10 to 3-11.  It sounds very much to me like your AC input voltage is dropping below the low voltage threshold as the charger ramps up.  This is a common problem if the wire run from the main supply to the inverter is too long or too small a gauge, or a combination of the two.  What happens is that, with no load, the voltage will read, say, 110.  Now the charger comes on line and starts drawing current; as the current builds to 20-30 amps, voltage drop in the input line causes the voltage at the input terminals to drop to, say, 100.  If that is below the AC LVCO, then the pass-through switch will open and the inverter will start powering the loads from the battery, as described in the manual.

One way to see if this might be what is happening would be to connect a quality AC voltmeter to the AC input terminals at the inverter, take a reading, then start the charger function.  Watch the reading to see if it drops as the charger ramps up.
 

I disassembled the unit enough to get at the AC board that has a Deltron 375-3PD relay mounted on it. 
The Deltron looks to me as though it should go to "NC" mode for the AC pass-thru...does this sound correct?

No, the pass through relay should be Normally Open.  It is closed only when the inverter sees valid AC input above the specified cut-out range as described above.  Note that the DR, like many Trace-heritage products, will not work at all (even in pass-through) unless the batteries are connected and above the DC LBCO.

The problem might be related to my leaving the inverter hot to the batteries for years.

I doubt it.  It is designed for exactly this type of service.

When the batteries are taken out of the circuit with the inverter master, the unit clicks. 

As noted above, the inverter requires proper battery voltage to operate.  Merely having AC power is not sufficient.

I cannot find any repair information on a DR2424. 

Xantrex does not publish repair information for its products.  You must return the unit to a Xantrex authorized repair center.

I would guess that some components are the same in most Xantrex units..or at least they function in the same way.

That's actually not correct.  Xantrex bought several inverter manufacturers, including Trace Engineering, Heart Interface, and StatPower (ProSine and ProWatt).  There is nothing at all in common between units of different heritage.  The DR series was a Trace Engineering product, and does share some design elements with other Trace products.  But note, for example, that there is almost nothing in common between the DR series MSW inverters and the SW series true sine wave models.

My question:  does the relay default to NC AC pass-thru mode when there's no battery power?

I don't understand what you mean when you say "default to NC."  "NC" means "Normally Closed," where "normally" means that the relay is closed when there is no power to it.  By contrast, NO relays are open when there is no power.  So an NC relay is closed "by default" and an NO relay is open "by default" if there is no power.

All relays in the DR function as NO relays, so with no DC power at all to the unit, nothing should be connected.

The AC pass-through relay is closed by the control system IFF battery voltage is present within limits AND the AC input power is available and within the limits you set as described above.

I found the relay on Deltrol Controls website.  http://www.deltrol-controls.com/files/rel375.pdf

That cut sheet is for several models of relay.  I'm not sure I understood which model you found in the unit.  But this type of relay is a common industrial product; nothing special about Deltrol over, say Tyco.  If the relay itself turns out to be bad (unlikely), you can replace it with anything that fits and has the same rating and terminal configuration  -- I can look up some cross-references for you if it comes to that.

-Sean
http://ourodyssey.blogspot.com

[Sean]

Wow, I don't know what's wrong with me today, but I had to edit that last post about six times due to typos, unclear statements, statements that should have been less definitive, and statements that, on re-reading, came across differently than I intended.

So if you got it in email, check the updated version on the board...

-Sean
http://ourodyssey.blogspot.com

[gumpy]

The AC pass-through relay is closed by the control system IFF battery voltage is present within limits AND the AC input power is available and within the limits you set as described above.

Wow, I'm impressed. That's the first time I've seen someone intentionally use the word iff, and use it correctly 

[Sean]

Thanks, Craig, but now that you've pointed it out, I realize I probably should not use mathematical expressions that are not commonly understood in my everyday writing.

"IFF" is a fairly common expression in mathematics and logic that means "If and Only If" -- and I probably should have just written that.

(Not to be confused, of course, with the military encrypted transponder system known as "Identification -- Friend or Foe" also abbreviated IFF.)

-Sean
http://ourodyssey.blogspot.com

[NJT5047]

Thanks for the quick response guys!   
The unit is screwed.   I've got the inverter out on the bench.   Prior to removing it the batteries were fully charged, and I disconnected everything, reconnected and turned on the battery switch. 
I have the manual and followed the 'start-up' proceedure.   
Disconnected the remote and tried to manually operate the unit.  It would start charging and over some hours switched off and then ran the battery bank stone dead.  Promptly recharged the batteries with another charger...they are OK. 
I may have another look for voltage drop in the AC line.  I shunted the inverter leads and everything works without issues....that doesn't mean the line voltage isn't dropping when the charger starts up. 
I checked line in without a load and it was 119 volts.   I understand that isn't really useful without a load.
The relay is unlikely to be the problem.   I found AC passthrough circuits "open" and thought that perhaps (optimistic thinking) the relay was welded in some alternative position. 
I'm going to keep the unit on the bench and connect it to a set of batteries.   See what happens. 
I've got 8 ga wiring (major overkill) between the panel-inverter-subpanel. 
The charger only draws upwards to 14 A for five minutes or so...then drops off fast.   
Unless a circuit breaker is failing...the rest of the system has been checked for loose leads.  None so noted. 
I ordered a marine 24V 20A charger which I'm going to install.  Unfun losing both charge and invert functions. 
I'm guessing that the fact that the inverter has totally depleted the batteries twice, the low-batt sense circuit has something in common with the AC pass circuit failure.
My mind's getting weak...but I would'a argued that the AC passthrough worked even when the inverter battery switch was off.   Wrong....
The AC board is almost $600 bucks.   Not likely I'm going to spend that guessing at what might be wrong.
It isn't worth sending back to the factory.   Not likely anyway. 
The unit is about 7 years old.   Lessee...that's about $70 bucks a year for a battery charger! 
We're using the bus for a few weeks, but when I get back, I'll bench test the sucker and post what happens.

Thanks again, JR

 

[Nick Badame Refrig/ACC]

Hi JR,

This maybe a long shot but, it happened to my first RS3000. The contacts on the 50amp internal transfer switch burned.

This caused 4 different fault codes due to arcing and load sense. It also did what you discribed in your first post.

Good Luck
Nick-

[Sean]

I've got 8 ga wiring (major overkill) between the panel-inverter-subpanel. 
The charger only draws upwards to 14 A for five minutes or so...then drops off fast.   
Unless a circuit breaker is failing...the rest of the system has been checked for loose leads.  None so noted. 

You are definitely looking at the right things.  I would defnitely re-install and then meter it while the charger starts up.

In addition to some kind of resistance in the input circuit (such as loose connection, improperly sized wire, etc.), there may be a very simple problem with the AC low voltage cut-out circuit.

If I understood the manual correctly, this setting is controlled by a trimmer pot, and a bit of crud or oxidation on the pot may be causing the cut-out setting to be off.  So if you think it should be cutting out at, say, 100 volts, it may instead be cutting out at, for example, 115 volts.

Depending on the results of the meter test, as a next step I would spray some contact cleaner into each of those pots, and run them through their full range of motion a few times before setting them back where they belong, to see if that has any effect.

-Sean
http://ourodyssey.blogspot.com

[Sean]

... it happened to my first RS3000. The contacts on the 50amp internal transfer switch burned.
This caused 4 different fault codes due to arcing and load sense. It also did what you discribed in your first post.

Nick has a good point -- oxidized contacts on the transfer relay, such as would be caused by arcing, will produce exactly the sort of voltage drop I suggested in both posts above.

Whether this could be the problem or not depends largely on whether the unit is monitoring line voltage ahead of the relay, or behind it.

It certainly bears looking into.  The shroud on the relay should be transparent plastic, and you ought to be able to see the contact pads and note any char there.

-Sean
http://ourodyssey.blogspot.com

[NJT5047]

Thanks again!   The relay is clear, and the contacts are visible--barely.   Components are situated in close proximity.   
The relay is one of the few parts that I can replace.  There's a large transistor looking gizmo mounted on the case (for a heat sink?)...black with 3 spade connectors, two screws thru a flange retain the thing.  3 wires-- two 12 ga and one 18 ga.  I intended to copy the id numbers but haven't done so yet.
There is one 18 ga grey wire that is soldered into the AC input line (I'll have to trace that back and see if it could be a sense lead?).  That might be the AC sense lead and if so, sense is ahead of the relay.   There is no crud visible.  The unit is clean and both interior and exterior look new.
Still, 7 years mounted in a bus that's stored in a barn may have some negative effect on the pots.   I'll mark and check those.  No harm at all.
Nick's experience may lead me to take a buckshot approach and replace the individual peices that I can access...relay and the transistor.  The relays are cheap.  The relay is 375 (p) 3pd...that's the printed circuit variation. 
Received my new boat battery charger today. Going to install that rather than work on the inverter.   
It's a 24V unit.   
If I can revive the inverter, I'll move the new charger to the cranking batteries.   They have never had a permanent mount charger.  Never been any trouble either since they are isolated when switched out. 
BTW, I did do the 'shadetree' thing last night and pecked on the relay case to see if the unit switched.  It did not.   I'm going to check for a switch control voltage.   That should settle whether the relay is at fault?

JR

[Sean]

JR, can you read the actual part number from the relay?  That will give us the coil voltage and contact configuration.

Again, I would definitely meter the AC voltage at the inputs while the charger is running as the next diagnostic step.

It is unlikely that either the relay or the power transistor is the problem with the control circuit.  I would clean the pots and check for blown caps.  A much more likely failure would be one of the ICs on the board -- not something you will be able to diagnose without a logic analyzer.

-Sean
http://ourodyssey.blogspot.com

[Nick Badame Refrig/ACC]

Hi JR,

I think you said the problem still exists on your bench..?? but, in case you havn't tried it, I would also look at the contacts on your external transfer switch

if you have one. This would also create the same problems as I discribed.

Good Luck
Nick-

[NJT5047]

The transfer switch contacts are in excellent condition.  I checked everthing carefully upstream from the inverter.  Initially, I thought I had an AC/panel  problem.  Didn't prove to be the situation.     
Right now, the unit is on the bench and does not have the 24V DC system hooked up.   I've got a couple of chargeable 8ds that I can set up.   The AC circuits are hooked up with a test load on the output.   All sufficient to power the charger which will kick in once the DC is hooked up. 
Sean, I looked at what I called the "AC" board found that it has no logic (or should I say no ICs)...the other board on the DC end of the unit has 15 ICs and all sorts of expensive looking gizmos.   Also has a good number of adjustable pots...which I'll 'adjust.'
Looked over both boards and don't see any smoked resistors or caps...or ICs.  Very clean, no obviously bad solder joints either. 
The DC end very likely controls the AC relay.  I can follow the wiring back to the DC board, but that's about where my level of understanding quits.
I'll get it hooked up to 24V and see if the relay has control voltage.  If so, bad relay...if not...anyone need a slightly less than perfect DR2424?   
In any event, the part number for the Deltrol looks like EN60947-4-1
The series is 375P-3PDT
I appreciate the input.  This doesn't look like something that is field repairable.  I'm sure Xantrex could, but the cost would be prohibitive.   There's a good bit of negative comments posted on the web regarding failed Xantrex units.  Parts are neither available, and when they are, really expensive. 
Still, I doubt I'll make it any worse dinking with it.   
I may call Xantrex and see what they say about the unit.  I've read that they'll produce schematics for non-current units.   I probably couldn't repair it even if I had a schematic.  Still, interesting thing to work with.
The inverter function was still working....??  Maybe I can still use that?   Hey...poor folk gotta do what they do! 

JR