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Growatt spf5000es with pressure pump 1.5kw


ahmed h

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GOOD DAY

WE HAVE RECENTLY INSTALLED A 5KW GROWATT INVERTER WITH A 5.12KW CYCLONE BATTERY WITH AN AVS 30 AS A BACKUP SYSTEM FOR LOAD SHEDDING. NO PANELS.

THE SYSTEM WORKS FINE TO RUN ALL THE PLUGS AND LIGHTS, HOWEVER WHEN WE CONNECT THE PRESSURE PUMP TO THE ESSENTIAL LOAD, IT SHUTS DOWN THE SYSTEM, IRRESPECTIVE OF WHETEHER WE A RUNNING IN BACKUP MODE OR OFF GRID.

ANY IDEAS ON WHAT THE ISSUE COULD BE.

 

THE PRESSURE PUMP IS A 1.5KW LEO.

 

THE LOAD ON THE INVERTER WITHOUT THE PUMP IS MAX 650 WATTS, SO I CAN'T THINK THAT THE INVERTER IS TOO SMALL TO RUN THE PUMP.

 

ANY HELP GREATLY APPRECIATED.

 

 

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On 2023/03/16 at 9:47 PM, ahmed h said:

the inverter gives a low bus voltage error when pump is connected to it and put on

My understanding is that during start-up, the power factor of the motor is very low, and the start-up current can be as much as 7x the rated current. That means that the inverter has to send a lot of VARs to the motor (Volt·Amperes Reactive), which largely travel from the DC bus to the motor, and back again. So it's not necessarily a 7x increase in required battery power (the battery mostly needs to supply real power, but also losses, which are proportional to the square of the current, so these could increase by a factor of 49x). But the 650 x 7 = 4550 VAR load in addition to other loads might be too much for the bus capacitors. [ Edit: Sigh. It's 1.5 kW x up to 7 = up to 10.5 kVA, in addition to the ~650 W of other loads. ]

You mention "recently installed" so I assume that the inverter is fairly new. Older inverters may have dried-out bus capacitors.

On 2023/03/15 at 10:26 PM, Jacques Ester said:

This can be harsh on your inverter.

Eactly!

Hopefully you can find an off-the-shelf soft starter for the pump motor. I think that pumps are worse than other motor loads, because there is a high mechanical load as well as the high electrical load, meaning that there is a large real power requirement as well as a large reactive power requirement. So the problem might actually be that the battery you have is a bit small for the task. 5.12 kWh is only 100 Ah; generally if you are approaching full load, you will need a 200 Ah battery. Perhaps attempt to measure the battery voltage during pump start-up. It's quite possible that the battery's BMS is disconnecting under overload. With a second battery module in parallel, each module will see about half the load current, and should be able to stay on during pump start-up.

Now that I think about it, that might also provoke the low DC bus warning/error. With the battery disconnecting, the only thing providing power is the bus capacitors, and they will drain very quickly when not topped up by the battery via the DC-DC converter.

Edited by Coulomb
650W was the other loads.
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