question

Charlie D avatar image

48V 15KVA Quattro showing random VE Bus overloads

Hi

I recently replaced an 8KVA Quattro for a 15KVA one, as my clients needs had been growing steadily recently. It is a monitored ESS system. Since its installation I am seeing regular overload warnings even though the loads are maximum 7KW. Often showing overloads at under 3000w. It shuts down at least once a day and did it again last night at midnight with a 1500w load. VRM data is giving me no indication of why it is doing this.

Anyone come across similar situation

ESSVRM
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I’ve had a similar issue recently, also with a 15Kva Quattro running ESS. I swopped it with a 10Kva that ran perfectly for 2 weeks, then installed a new 15Kva and the problem returned same day. Changing the grid code to other or none (I can’t remember now which one) fixed it. Obviously you will need to take care of anti islanding protection.

1 Answer
Guy Stewart (Victron Community Manager) avatar image

I have seen similar situations where batteries connections and interconnections were an issue, or battery cells were weak, but the bank as a whole was strong. So battery voltage didn't collapse, but there were enough dips in the voltage for a very short time, to increase the current.

Combined with a large surge load, eg a compressor which might only be 2400W continuous, but when switched on can pull 12 kW+. As soon as the surge load is over, the battery voltage instantly recovers, so it's hard to diagnose unless you are there to see it happen.

It can also be that some loads are pulling a very strange sine wave or power factor, and the usual rules do not apply. If possible, isolating loads to see if there are any in particular that cause the issue.

If you find some, perhaps changing the AC wiring configuration to lot those run directly off the grid but visible to the ESS system with an energy meter.

You didn't put the VRM information, or give permission to view it, so I can't see if there are any other signals that seem something is amiss.

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Hi Guy,

The battery bank is 1130AH 48V OPZV approximately 18 months old. the system is grid connected with the grid set to optimize mode and no feed back. I have noticed that their pressure pump (1.5kw) or any other reasonable size load cutting in causes power to be taken from the grid rather than from the batteries. The inverter makes a lot of clicking noises that seem foreign to normal use.

If you can have a look on VRM it would be appreciated. I am the Victron dealer in Vanuatu and it is under our login of savvysolarvanuatu@gmail.com (my email if you need more info). The site is Mulham Vanuatu.

Hi @Charlie D,

I did a quick look at the graphs, and as Guy suggested, your batterie looks very weak, it's empty in no-time and voltage swings very quickly under load / charging.

Also the inverter gives a high DC-ripple warning sometimes, also indicating a bad battery or poor connection.

I'd first check the batteries.

Charlie D avatar image Charlie D Daniël Boekel (Victron Energy Staff) ♦♦ ·

Hi Daniel

I have been back to the system and removed all battery cables and cleaned terminals and connectors, nothing too bad here. Checked all battery voltages and they were all very close to 2.2V, again nothing standing out here. All connections through to inverter are new but I checked for anything loose.

The system is still having random high AC output spikes, and lots of inverter overload warnings even at very low output currents. The inverter shut down this morning at 1.44am while supplying 1300w. Then again at 5.15am supplying 1100W. This is definitely not caused by a weak battery bank

I watch the color control for a while and it does not seem right. It is a grid connected ESS system and every time a pump or a load kicks in it dragging power from the grid rather than from the batteries

I have had this from a Multiplus once before and I re-installed firmware and software which cured it but not in this case.

Can you please check out Mulham Vanuatu VRM site again at the times it shut down this morning and see if you can see something I can't.

Thanks

Some observations:

-your batteries are empty while still showing 55% SOC, so your battery monitor is not correctly configured - batteries are a lot less capacity then set in the BMV

-I cannot find an obvious reason for the overload warnings and alarms, so you'll have to do some digging to try to get this to happen / change out the unit with another one to see if that fixes the problem.