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eyub avatar image
eyub asked

3 PHASE SYSTEM WITH GENSET ( STARTING CURRENT)

we have a customer requesting a solar system for oxygen pumps in his fish farm, he has 4 oxygen pumps each of 2.2 kW rated power and they are three-phase he needs to operate them 24/7 there is also grid in the site for 8-10 hour per day and there is also a generator, he wants to operate using solar during the day time and about 2 hours battery backup at night or during a cloudy winter day, and the Genset will start when the batteries are empty and there is no grid.

can we offer him a solution with Victron at this big back-up capacity, also note that there is no suitable place for the battery so we have to create a small cabin and cool it with a small 12000 BTU AC

I thought of :

19.44 kWp solar (54 panels 360 watts divided for three sets each 18 panels for each inverter)

3 x 5 KVA Quattro

3 X 250/100 MPPT charger (1 for each inverter)

24.576 kWh battery ( 12 X LiFePO4 Battery 12,8V/160Ah Smart ) considering 85%DOD


SO MY QUESTIONS ARE:

1- can this combination (especially the inverter) stand the starting current of this load ( I don't know the starting current the pumps are installed and I couldn't find their datasheet online but I attached the nameplate photo)

2. can I replace the batteries with LONG LIFE GEL OPZV 2V with considering 60% DOD, will they stand the discharge current of the load since the load during the battery back up?

- I attached the load calculation and the motor nameplate

thanks

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MultiPlus Quattro Inverter Charger
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Alexandra avatar image Alexandra ♦ commented ·

@eyub

The 5KvA Quattros may not be quite enough. The start up currents on motors can be heavy if they do not have great power factor correction on them. Or at least soft start devices. we have even seen motors installed with electrical wiring that is too small making the whole situation even worse.

So 2200W is active the power rating but the apparent power may be very different.

Watts law for three phase is easy to work out the active power though.

Current (amps) = power (watts) ÷ voltage (volts) ÷ square root of 3 (1.732) ÷ power factor

2200÷380÷1.732÷0.8 = 4.18A. 0.8 as a power factor is generous for motors.

Also on another note, is there a reason why you are choosing to build battery banks with 12V batteries instead of a 48V system? Battery balancing will become an issue and not all batteries can be series parallel connected.

Is the site running are you able to power log it?

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tilo avatar image
tilo answered ·

As Alexandra said, if 4 pumps start at the same time, the startup current may overload the system. You may install a time delay relay to 3 of the 4 motors so they do not start at the same time.

Do not make a separate battery bank for each inverter. You must use one battery bank for the 3 inverters.

The 12V 160Ah Smart can be series connected to 48V. In any case use 48V.

What is the temperature in this place?

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