Xantrex SW2512MC2 120 volt shore power and generator both on G2 line in

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Scalloper1

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Oct 21, 2012
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Xantrex op manual supplement says shore power should be on G1 or will void warranty, mine has both shore power and gen. on G2. Does anyone no why it would be wired this way and would there be any adverse effects from wiring as manual sup. says? 2005 HR Navigator, 8 Dekka GC 15 batteries wired in series and parallel for 12 volt system. SW2512MC inverter.

 
Can you provide a direct quote from the referenced supplement, or provide a link to it?  Your terminology of G! and G2 does not correlate with the documentation I have for that model inverter. My manual simply refers to the AC inputs as AC1-IN and AC2-IN.  These are inputs to an internal transfer switch.  Shore power on AC1 would allow default to shore power, but give priority to Generator power (when turned on) if the Generator is wired to input AC2.

Most some motor homes would have a transfer switch installed in the AC path prior to the inverter to provide the selection of shore/Gen power and then feed the result into the inverter on AC1 input via a single feed.

Sorry if I've made an invalid assumption of your question.
 
I can't find any such reference either - maybe only in that supplement you mentioned?  Furthermore, it doesn't make any sense that I can see. Perhaps you could  do a copy and paste or post a scan of the relevant page?  There are wiring diagrams for configurations that involve stand-by generator and other applications that may not be wired the same as an RV (mobile) application, where there is an external transfer switch that masks the generator from the inverter.

Normally the inverter AC In comes from a breaker in the coaches 120vac load center (breaker box).  There would be an external  transfer switch ahead of that that would switch between generator and shore power, giving preference to the generator if it is running. This means that the inverter is unaware of whether the actual source of the 120v power was shore or generator. Both would feed the AC-In of the inverter, but only one could do so at a time. There would be no direct connection between generator and inverter. I'm fairly confident that your Navigator is wired that way, but cannot say so unequivocally.
 
Following up after reading the manual further, it states that the alternate generator input is used when there is no external transfer switch. Since you do have an external switch, only one of the AC In's should be used. I would have thought that would normally be AC1, but it appears that HR/Monaco has elected to use AC2 in your coach. I can't think why that would be, but I also can't think of any harm from that. However, I don't know the SW2512 internal design well enough to know what, if anything, is different about AC2 vs AC1.

Here is what little it says about the two AC inputs when an External Transfer Switch is employed:
EXTERNAL TRANSFER RELAYS
It is not acceptable to switch the AC input from one AC source to another while the inverter is
connected. This applies whether the inverter is in battery charging mode or inverter mode. Switching the
AC input from one source to another can result in a loss of synchronization that can cause a severe
overcurrent condition that is far worse than short circuiting the inverter. Two separate AC inputs are
provided to eliminate the need for use of external transfer relays. If a transfer relay is used, it must provide
a center ?OFF? position (?break before make?) that causes a loss of input power to the inverter for a period
of at least 100 milliseconds. This will allow the inverter to disconnect from the original AC input and then
re-synchronize to the new AC source although the same AC input terminal is being used. During the
transition period, the inverter will have to operate the load while it re-synchronizes to the new AC source
(about a thirty-second period at the minimum). Most transfer relays will switch too fast for the inverter to
detect - and will cause the inverter to lose synchronization with the AC source. This is indicated by the
inverter shutting down upon transfer and the red overcurrent LED indicator flashing or turning on.

Manually, hand operated transfer switches may be acceptable since the transfer time can be slow enough
for the inverter to detect. The switch must go through a center ?off? position. They are often used to switch
from one generator to another. Since the inverter has a separate AC input for a utility grid, a transfer
switch is not required to switch from the utility grid to a back-up generator. The inverter will not allow the
generator to be connected to the utility - if both are available, the generator will be disconnected and the
inverter will connect to the utility on AC HOT IN 1.

I'm sad to say that I have seen cases where the RV manufacturer ignored the installation instructions in the component manual.
 
Gary, the supplement the OP referenced says the internal software has been changed to give priority to the generator on AC2, so the shore power should be applied to AC1.  (this is done to be consistent with the RV Pseudo standard of default=shore power and override/priority=Generator.)

This would only be of consequence if there is no external transfer switch installed prior to the inverter AC inputs.  I can't imagine that being the case.  I don't think it has any bearing on the OP's current problem either.  JMO
 
Sorry my bad. Manuals are in motorhome at electrical repair shop, I misinformed when I said G1 and G2, AC1 and AC2 are the correct terminology. I was thinking I must have a separate transfer switch with both shore power and
generator wired on AC2. My concern was if this had anything to do with failure of SW2512 inverter after reading supplement that Xantrex would void warranty because shore power and gen. both being wired to AC2.  Not worried over warranty, concerned if inverter is wired wrong. From what I've read I think Lou is right about gen. being priority. Thx for your replies.




 
If I am following all this they are using AC-2 because they have already wired a transfer switch upsteam and either source is providing the priority source after the first transfer switch although I don't think it makes any difference.

To answer your concerns this should not affect the operation of the Xantrex SW2512MC2.
 
If I am following all this they are using AC-2 because they have already wired a transfer switch upsteam and either source is providing the priority source after the first transfer switch although I don't think it makes any difference.

I think so too. I'll go one step further and suggest that it makes no difference which AC input is used when there is an external transfer switch.
 
Gary RV Roamer said:
I think so too. I'll go one step further and suggest that it makes no difference which AC input is used when there is an external transfer switch.

Actually, I think it just might make a big difference under the right conditions.

The data in the supplement indicated that the AC1 and AC2 inputs were under internal program control, and that their operation had been reversed from earlier versions.  This would indicate to me that they are not just the usual contacts on a mechanical relay contactor.  The requirement to move the shore power feed to AC1 was the whole purpose of publishing the supplement. 

If functional power (and program intelligence) is required to switch the input from AC2 to the output during  pass through, then on a defective or dead inverter it probably wouldn't work as desired if the input was on AC2.  I'm assuming that, like the mechanical TX switches we are used to, if the input was on AC1 it would simply pass through on N/C contacts even with no power to the inverter.

This is precisely why most RV transfer switches are cabled with shore power being the default (requiring NO action by the switch) and the Generator power on the override input.

Under normal operating conditions there probably would be no difference other than possibly a delay when starting from a complete no power condition (waiting for AC2 to transfer).
 
Lou:

The Xantrex XM1800 Pro I just bought defaults to AC pass through if the inverter fails.
 
Jeff said:
Lou:

The Xantrex XM1800 Pro I just bought defaults to AC pass through if the inverter fails.

That's as it should be, Jeff.  A major knock on some Xantrex inverters of the past was that certain failures of the inverter would cripple the pass through function.  I think the Prosine 2K and 3K may still be that way.

The old Trace inverters were not that way until Xantrex got hold of them.
 
I wonder why the SW2512 has such complex requirements? Some attempt to avoid a need for an external transfer switch, I guess?  My Xantrex RV2512 (also a Trace design) has only one AC input and works nicely with an external transfer switch.
 
Gary RV Roamer said:
I wonder why the SW2512 has such complex requirements? Some attempt to avoid a need for an external transfer switch, I guess?  My Xantrex RV2512 (also a Trace design) has only one AC input and works nicely with an external transfer switch.

I got the impression from the documentation that the SW2512 was not specifically designed for the mobile environment (RVs and Boats) and that the two AC input design was a holdover from a unit designed to be the main transfer switch point between multiple power sources.

Correctly wired, the two AC inputs do provide the same functions as an external TX switch plus the normal TX switch in a typical I/C.
 
It only provides the "same function" insofar as the inverter circuits are concerned. An RV also has air conditioners, a water heater, a fridge, and maybe some additional circuits or appliances (like an Aquahot) that do not pass through the inverter, so an external transfer switch is still a requirement.
 
Now I realize that I found one of the most informative RV forums, you guys are answering my questions before I even ask them. Your insight is inspiring thanks for your trouble in this matter.  :)
 
Gary RV Roamer said:
It only provides the "same function" insofar as the inverter circuits are concerned. An RV also has air conditioners, a water heater, a fridge, and maybe some additional circuits or appliances (like an Aquahot) that do not pass through the inverter, so an external transfer switch is still a requirement.
I thought I said that it appeared to be designed for a non-RV application.
 
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