About the current

kcbibek310
kcbibek310 Registered Users Posts: 21 ✭✭
in Solar Water Pumping #1
What happens if the current output of VFD is less than the rated current of Solar Pump. Is this responsible for the failure in operation of motor? Please give me reasons with explanations as possible. 
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #2
    When sizing a drive to run a motor, be it a pump, fan or whatever, the drive should have a capacity greater than the load to reduce stress on the electronic components, around 120% or greater than the load, is a general benchmark. Some drives, Danfoss for example, require  a hand shake with the motor in the setup procedure, which tests the motor to establish compatibility, if not compatible, it is rejected.

    Not all drives are created equal, so some general a calculation is needed to establish if there is compatibility, but certainly using a drive which cannot support the load is not part of the criteria. Also establish if the motor has the insulation required to employ a drive, as frequently drives can induce high voltage spikes which can compromise the insulation of the windings.

    Not sure if this answers the question, but hope it helps.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
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  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    edited October 2017 #3
    If the VFD reduces both voltage and frequency to protect itself, all can be fine.   Also note that the rated current of the pump may not equal the actual current of the pump.   Actual can  be higher, which overheats the pump.

    I am available for custom hardware/firmware development

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  • kcbibek310
    kcbibek310 Registered Users Posts: 21 ✭✭
    #4
    Sir, i have a motor with rating 2.2 kW and 6.5 A rated current. My solar panel rating is 7.2 A short circuit and I have a VFD of 4 kW with output rating 9 A. My question is what happens if i made two parallel connection of solar panel and  total output current of pannel become 14 A. Does VFD manages current rating? Does it seem overcurrent? Does if effects motor operation? Assuming i have manages the voltage ratings.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited October 2017 #5
    The drive would only use the current needed to support the load, along with inherent losses, the extra capacity would not be used, having the extra capacity however would allow for longer run times, when the sun is not at optimum angle to the array, which is beneficial. The short circuit amps of a panel is not what the panel can provide in normal conditions, the Imp is the actual maximum available in ideal full sunlight.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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