Xantrex 4048 problem

[Ralph Day]

Hi all
I've lived off grid for 6 years with few problems with my 10kw genset feeding power to my SW 4048. Now, I've got problems

The system now has grid power available...cheaper than diesel for charging batteries.

The problem is this: when grid power is applied (it doesn't matter, ac1 or ac2, things charge and bypass to loads just fine...when you remove the power supply (cut-off switch) the inverter doesn't immediately revert to inverting, it chugs along at minimum cut off voltage ac in charge/bypass mode. At this point there is NO power supplied (cut off switch OFF), yet the inverter will not invert.

When shutting off the generator via the inverter there's a clunk of a relay disengaging from the source. However, if you start the generator (or utility supply it seems) and supply power to the inverter it will charge/bypass as per owner's manual specifications...but when you remove that source it won't disengage as the manual suggests it should (in the testing mode section...relay will disengage and begin inverting immediately).

My work-around is to shut off the cut off switch, shut the inverter to OFF position then immediately cycle to ON. This shuts off the whole house but only for a few seconds...you hear the relays activating when doing this. The inverter shutting down must disengage any incoming power via the relays.

Any thoughts? I've tried changing the ac2 to ac1, the only difference is the drop of supplied power is much shorter on ac1.

Thanks for any thoughts

Ralph

[niel]

i'm just guessing here, and i assume it just started these symptoms you listed and worked before, but it almost sounds like a stuck relay. i'm probably wrong, but who knows it might be the case.

[RCinFLA]

Has this condition always existed on this SW4048?.

I am not sure what you mean by :

"it chugs along at minimum cut off voltage ac in charge/bypass mode. At this point there is NO power supplied (cut off switch OFF), yet the inverter will not invert"

On SW's the ACout is connected to inverter output and there are two relays that connect AC1 or AC2 in parallel with ACin source.

There are two possible modes when AC1 and AC2 are supplying power.

In standby mode the inverter is shut down with control sync'd to ACin source and ready to immediately activate if ACin goes away.

In normal run mode the inverter is active running in parallel with ACin source. Battery charge current is drawn from AC source as necessary but not greater then AC input source current setting or AC charge input current settings. If battery is charging then inverter is active.

I have two SW4048's, I have noticed that if load or charge current is low the disengagement of ACin relay is slow. This only occurs on the unit I have with newer software revision.

This only occurs if AC input breaker is opened. Normal grid going down is usually an overload. Under this condtion the relay immediatedly releases.

[Ralph Day]

Thanks for the quick replies.

Q1: I don't know if this ever happened before, I only ever had the genset and always controlled it from the 4048, so it always dropped power instantly via relay for ac2.

Maybe RC has a clue regarding low load or charge current. The only times I've tried in the new configuration there had been minimal charge and load draw (charging amps dropped down to 1 amp ac). Inverter is definitely in normal run mode.

By chugging along I mean that the house loads are still active/lights on, but the voltage output is down to the minimum set in the progammable parameters (111vac min). Power is coming from somewhere, but the led's indicate ac2 in ok, bulk charging not inverting...but absolutely no outside power available at ac2 connections.

Maybe I'll try a higher load shutdown instead of least amount possible charging current. Cycling the inverter to OFF then ON works, but it's not my preferred solution.

Ralph

[RCinFLA]

This is confusing me:

"By chugging along I mean that the house loads are still active/lights on, but the voltage output is down to the minimum set in the progammable parameters (111vac min). Power is coming from somewhere, but the led's indicate ac2 in ok, bulk charging not inverting...but absolutely no outside power available at ac2 connections."

From this I get,

1) ACout is still running at 111 vac.

2) LED for AC2 is solid 'ON', this would mean AC2in is supplying power. (at 111vac)
This is confusing as you said you disconnected ACin so both green LED should be off. This might mean the AC2 relay is stuck, perhaps with contacts sticking together (welded contacts.) The relay is a Deltrol 375 (spec attached, its a 12vdc coil)

"bulk charging, but not invertering" You don't understand how SW operate. The inverter must be running to charge. The inverter is bi-directional. The only difference between inverter pushing out power to ACout and charging is the way the three power transformers secondaries are instantly stacked.

Normally if an ACin (AC1 or AC2 input) is present, all the charging current and ACout current is coming from ACin. This is not true under certain setup conditions.

For example, if you set AC2 in to allow a maximum 20 amps input from generator, and total ACout load is 30 amps, then under this condition the inverter will supply the 10 amps necessary to make the 30 amp ACout load.

If AC2 in is set to 20 amps max draw from gen, and ACout load is only 8 amps then 12 amps is available for battery charging. This assumes the AC charging max amps setting is greater then 12 amps. SW always gives priority to ACout load. It will automatically back down charging current if more of the ACin current is needed for supplying ACout load.

When ACin (AC1 or AC2) is present, the inverter will take on the frequency and voltage of that source. If ACin is disconnected the inverter will continue to pick up the load at the freq and voltage of what the ACin was. I am not sure if it will gradually migrate the voltage and frequency to 120vac and 60 Hz or just leave it at last ACin setting. I think it moves it to 120vac/60hz over several seconds. If gen re-appears at 111 vac, the sync process (blinking green light) will gradually migrate inverter to match the voltage, frequency, and phase of the generator before closing the AC2 input relay.

Your generator output voltage may be low or you may have a stuck relay. It would be surprising if both AC1 and AC2 have 'welded contacts'. Moving gen to AC1 should avoid any AC2 stuck relay.

[Ralph Day]

Thanks RC

I do understand how the charging and bypass work on the SW, I'm just a crappy writer and sometimes don't get my point across properly.

The chugging along should not have been said. More clearly: when the ac power is disconnected (by a 60 amp knife switch, zero power) the 4048 still has the led's indicating ac2 in green, bulk charge yellow. I know this should not be, but there you go.

As far as stuck relays goes, I haven't tried the generator operation in a while, tha'ts tomorrow's job, to see if it works as it always has.

I will also try disconnecting with a heavier load present.

If this puzzling behavior persists do you think that cycling the inverter off then on would have any adverse effects on components? It seems to me that cycling on/off runs the relay through an on off cycle as well. It's so far the only solution I've found that works.

I'll update when tomorrow's experiments are completed. This requires changing the transfer switch from utility to generator (in the garage).

Ralph

[RCinFLA]

Sounds like a stuck power relay.

When relay coil is de-energized the controller sees any voltage on ACin node as coming from outside source.

If relay is contact welded and stays connected when coil is de-energized then the controller thinks external AC source is present. Inverter will chase its tail.

Attached is schematic of power control board.

Without battery power, nothing runs in inverter. Relays should be open. With battery disconnected and both AC1 & AC2 breakers open you should be able to check relay contacts (should be open) with ohm meter. Check ACout to AC2in terminals at inverter and ACout to AC1in with ohm meter.

If contacts welded, you might be able to separate and re-burnish the surfaces. A new relay would be better if you can find one.

When I first saw how they used a three pole 30 amp contact rated relay for a 60 amp connection I was surprised they got the design by UL. You know upon normal AC grid going down overload detect release, one of the three contacts is going to leave the party a little late, taking a hell of a current disconnect break.

[Ralph Day]

Hi
5 minutes of troubleshooting and I've got the problem solved...i think, at least workable.

Tested the generator operation and it is as always, when started by the inverter it synchronizes, shutting down as normal the ac2 relay disengages from power and begins to invert immediately.


Second test was done by re-applying grid power as the power source, but not feeding the inverter as yet (60 amp knife switch off), with the remote start wire interrupted (at the 5 amp fuse, removed) generator start was initiated at the inverter. Ac2 flashing as per usual, when first relay clicked (assuming it was ac2 ) I closed the switch allowing power to the inverter. After the programmed delay it synch-ed to the supplied power and commenced charging and bypassing loads.

Then the tense part...I cycled the generator controls on the inverter to OFF and things behaved just as if it was the generator supplying power...immediate cutoff of supplied power and start of inverting. Just what I was looking to see.

My plebian explanation is that the ac2 relay is functioning normally (obviously), but something sensing supplied power when the inverter is not in control (generator controlling) is malfunctioning.

My plan to make it easy to work this way? Install a switch on the remote start wire, one position will be closed, or ON (labeled generator function) so that generator does actually get remote started, in the open position, or OFF (labeled as utility function) the remote control will be disabled and will function as tested above. This removes the need to shut off the inverter when ending applied power (utility) charging/usage.

Hope that's as clear as mud. Something is not right, but the inverter works, it just needs attention.

Thanks for your input RC, it helped me figure out what I needed to do in order to find a workable solution,

Ralph

[RCinFLA]

You lost me on description of second test.

Don't forget there is a 40 second 'cool down' function on SW for generator.

The remote generator control does not have anything to do with ACin sensing control other then 'cool down' disconnects AC2 power relay so generator runs unloaded for 40 seconds to allow it to cool down before releasing relay RY7 ignition control to shut down generator.

If AC1 shows up during a gen run on AC2, a gen shut down is initiated. Sequence is release AC2 power relay, inverter changes sync to AC1, then closes AC1 power relay. Gen completes its 40 second cool down before RY7 shut down.

Also check all the other gen setup function parameters.

Opening a breaker to ACin's can produce squirrely results. SW has trouble sensing open circuit on AC1, AC2 inputs, one of reasons it fails to comply with UL1741. The only SW sense capability is the current reading on AC2. What is difference between a condition of light load on AC2 (no need for charging, no load on ACout) and a breaker disconnect on AC2 in? Answer, not much difference.

SW really needs a low impedance source to either pull it out of freq range or pull down voltage out of range to know its time to disconnect the power relays.

[Ralph Day]

Second test was done by re-applying grid power as the power source, but not feeding the inverter as yet (60 amp knife switch off), with the remote start wire interrupted (at the 5 amp fuse, removed) generator start was initiated at the inverter. Ac2 flashing as per usual, when first relay clicked (assuming it was ac2 ) I closed the switch allowing power to the inverter. After the programmed delay it synch-ed to the supplied power and commenced charging and bypassing loads.

What I meant here is I ''started the generator" but there was no remote start connection with the generator. Normally this would result in several re-start attempts. I closed the switch allowing 120vac to feed the inverter (ac2), not from the diesel generator but from the utility. The inverter synch-ed, charged and shut down properly.

I think what I was observing was what RC described as ''squirrely" .

Ralph