PIP5048MG - Earth and Battery

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TitchRSA
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PIP5048MG - Earth and Battery

Post by TitchRSA »

Hi all,

Question 1:
When the 5048MG is totally switched off or disconnects load as a result of going below the battery Cut-Off (program #29) does the inverter connect Neutral and Earth?
I get a tripping RCD on my 3-phase input side when this happens.

Question 2:
Why when in line-mode do the 5048MG inverters still use battery (about 40W)?

Many thanks.
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coulomb
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Re: PIP5048MG - Earth and Battery

Post by coulomb »

TitchRSA wrote: Wed, 29 Jan 2020, 15:13 When the 5048MG is totally switched off or disconnects load as a result of going below the battery Cut-Off (program #29) does the inverter connect Neutral and Earth?
If the inverter connects neutral and earth at all, then I'd expect it to connect the way the 5048MS models do:

Image

So with the power off, all the relays are off, so the neutral and earth would be connected.

When the load is cut off, that's a different relay (again, presuming similarity with the 5048MS). In line mode, the neutral out would be connected to neutral in, and not to earth.
I get a tripping RCD on my 3-phase input side when this happens.
RCDs on the AC-in are often nuisance triggered by the EMI neutral and active to earth capacitors. It's best not to have an RCD at the AC-in (connect the AC-in before any RCD). You want RCDs on the output, of course.
Why when in line-mode do the 5048MG inverters still use battery (about 40W)?
I expect so, again based on similarity with the 5048MS models. They use about 35 W (from memory) when the inverter is not running, and about 50 W when it is. That always seems to come from the battery. When utility charging, there will be some 50 W lost because the inverter is running (albeit in reverse).
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.
TitchRSA
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Re: PIP5048MG - Earth and Battery

Post by TitchRSA »

Thanks again @coulomb
Always valuable responses.
So with the power off, all the relays are off, so the neutral and earth would be connected.
Great - wish this was documented.
When the load is cut off, that's a different relay (again, presuming similarity with the 5048MS). In line mode, the neutral out would be connected to neutral in, and not to earth.
OK - so that could well play havoc with an RCD - thanks.
RCDs on the AC-in are often nuisance triggered by the EMI neutral and active to earth capacitors. It's best not to have an RCD at the AC-in (connect the AC-in before any RCD). You want RCDs on the output, of course.
Excellent advice. Going to change that soon.
I expect so, again based on similarity with the 5048MS models. They use about 35 W (from memory) when the inverter is not running, and about 50 W when it is. That always seems to come from the battery. When utility charging, there will be some 50 W lost because the inverter is running (albeit in reverse)
.
When one has 3 inverters running that's about 150W per hour - so that's whats chomping battery when its low. Only had about 1200W in the battery so it would have reached the Cut Off around 6 hours - which is pretty spot on with the time the data reflects. Thanks for this.
TitchRSA
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Re: PIP5048MG - Earth and Battery

Post by TitchRSA »

Hi @coulomb
RCDs on the AC-in are often nuisance triggered by the EMI neutral and active to earth capacitors. It's best not to have an RCD at the AC-in (connect the AC-in before any RCD). You want RCDs on the output, of course.
This morning I moved the 3-phase AC Input circuits directly onto the incoming main 3-phase utility circuit breaker (4 pole, 3 phases + neutral). Separate phases to neutral per inverter. No luck! As soon as I switched the single phase AC CB (L+N) on to any of the 5048MG inverter AC inputs the 3-phase (4 pole) RCD tripped and this is with the Inverter AC inputs connected directly to utility.

The inverters had switched over to Line-Mode during the night as a result of program #12 (Switch to line-mode when battery gets to 48V). No issue there and all was good. I removed all loads from the inverters via a 3-way bypass switch (OFF) before switching off Utility and working on the change.

There are two systems here - one made of 3 x PIP5048MG and 6 x PIP4048MS - all were connected directly to Utility and all neutrals are common.

When switching on the AC CB input to any of the 4048's the RCD also trips. My guess is because they are picking up the 'Earth/Neutral characteristic' from the 5048's.

When I moved the AC Inputs back onto the RCD output, the tripping stopped - how wierd is that?

The 3-phase utility RCD does feed other loads directly - these are loads we do not run off the inverters. From the 3-phase RCD we branch out to single phase loads balanced by phase.

All loads are connected to single phase RCD's (unless a 3-phase circuit in which case they have their own 3-phase RCD) and no load RCD's have tripped.

Any ideas on how I can get around this problem?

Many thanks
Titch
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coulomb
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Re: PIP5048MG - Earth and Battery

Post by coulomb »

TitchRSA wrote: Thu, 30 Jan 2020, 12:48 This morning I moved the 3-phase AC Input circuits directly onto the incoming main 3-phase utility circuit breaker (4 pole, 3 phases + neutral). Separate phases to neutral per inverter. No luck! As soon as I switched the single phase AC CB (L+N) on to any of the 5048MG inverter AC inputs the 3-phase (4 pole) RCD tripped and this is with the Inverter AC inputs connected directly to utility.
So the RCD that trips is between the outputs of the three inverters and the loads?
When switching on the AC CB input to any of the 4048's the RCD also trips.
So this is the same RCD as above, on a completely different system?
When I moved the AC Inputs back onto the RCD output, the tripping stopped - how wierd is that?
Seven :)
I think you must have something weird with how you are commoning the neutrals. You have to be really careful that no neutral current can be sensed by the RCD other than from the loads.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.
TitchRSA
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Re: PIP5048MG - Earth and Battery

Post by TitchRSA »

So the RCD that trips is between the outputs of the three inverters and the loads?
The 3-phase RCD is on the Utility 3-Phase input - then that branches to the Inverter AC Inputs - no more RCD's in the way. The RCD is there because there is a 3-phase machine attached to the Utility. There are also other single-phase loads on the utility and they all have their own single phase RCD's, but these are placed between the 3-phase RCD and the single phase loads.
When switching on the AC CB input to any of the 4048's the RCD also trips.
So this is the same RCD as above, on a completely different system?
The Utility 3-phase RCD feeds both systems and so the input Neutrals for both systems are all connected. The Inverter Output neutrals are isolated for the 2 systems.

Perhaps I should remove the 3-phase RCD from supplying single-phase loads and use it just for the 3-phase machinery.
When I moved the AC Inputs back onto the RCD output, the tripping stopped - how wierd is that?
Seven :)
I think you must have something weird with how you are commoning the neutrals. You have to be really careful that no neutral current can be sensed by the RCD other than from the loads.
I am looking at this now as the wiring is inherited so there may well be a neutral anomaly somewhere.

Thanks for the quick feedback.
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coulomb
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Re: PIP5048MG - Earth and Battery

Post by coulomb »

TitchRSA wrote: Thu, 30 Jan 2020, 14:01 The 3-phase RCD is on the Utility 3-Phase input - then that branches to the Inverter AC Inputs - no more RCD's in the way.
OK, but didn't you say you made the change to put the AC-ins of the inverters directly to the 3-phase breakers, i.e. before the 3-phase RCD?

If turning on the inverters trips the RCD and no inverter current is supposed to be going through the RCD, then you have some very screwy wiring, probably neutrals.
The RCD is there because there is a 3-phase machine attached to the Utility. There are also other single-phase loads on the utility and they all have their own single phase RCD's, but these are placed between the 3-phase RCD and the single phase loads.
With all those RCDs, it sounds like you need at least 5 neutral bars (though some might be so small as to become just BPs (single screw connectors). Do you have such?

You're going to have to puzzle 'till your puzzler is sore, or employ an electrician to sort it out. Think about what currents each RCD "sees".
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.
TitchRSA
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Posts: 26
Joined: Wed, 05 Jun 2019, 14:00
Real Name: Titch

Re: PIP5048MG - Earth and Battery

Post by TitchRSA »

The 3-phase RCD is on the Utility 3-Phase input - then that branches to the Inverter AC Inputs - no more RCD's in the way.
OK, but didn't you say you made the change to put the AC-ins of the inverters directly to the 3-phase breakers, i.e. before the 3-phase RCD?
Erm no. We have a main Utility breaker then the 3-P RCD. I only moved the 3-P Inverter in connections to the circuit breaker. This is causing some of the RCD problem because the other single phase circuits (across the 3-P scope) were still on the RCD.
If turning on the inverters trips the RCD and no inverter current is supposed to be going through the RCD, then you have some very screwy wiring, probably neutrals.
I think so too - waiting for close down this afternoon to check.
The RCD is there because there is a 3-phase machine attached to the Utility. There are also other single-phase loads on the utility and they all have their own single phase RCD's, but these are placed between the 3-phase RCD and the single phase loads.
With all those RCDs, it sounds like you need at least 5 neutral bars (though some might be so small as to become just BPs (single screw connectors). Do you have such?
I have 4 neutral bars.
You're going to have to puzzle 'till your puzzler is sore, or employ an electrician to sort it out. Think about what currents each RCD "sees".
Going to remove the 3-P RCD this afternoon and just put it on the 3-P load. The single phase circuits with single phase RCD will then be connected directly to the Utility as will the non-RCD Inverter inputs.

Will let you know how the puzzle works out :)
TitchRSA
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Re: PIP5048MG - Earth and Battery

Post by TitchRSA »

Hi @coulomb
Will let you know how the puzzle works out :)
All sorted on the tripping issues. The 'Electrician', it appears, cannot read circuit diagrams - I am the architect of the engineering designs and I have no clue what hymn sheet he was working from. This is Mauritius.

Most of the issues were poor wiring and much of that was the poor neutral connections you mentioned. I re-wired most of that last night, ensured the RCD was only servicing the 3-P loads, checked all CB and load connections and re-balanced the single phase loads across the 3 phase system. All seems fine now. I did come across a 3-phase steel saw which has some form of capacitance across P1 and P3 and allows for a momentary 'short' of the 2 phases. Not significant but did play a part in tripping the RCD the way things were wired. It doesn't do that any more.

Thanks for your assistance.
Titch
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