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  • Users: VMMF
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  1. VMMF

    Wye-Wye Transformer and grounding

    Could you provide some technical details for this? What could be causing the customer equipment damage e.g burnt refrigerators? Was the delta facing the grid and the wye facing the customers? Was there any kind og earth/ground fault resistor (NGR) on the wye? Were this pole mount or pad mount...
  2. VMMF

    How much better are voltage optimizers compared to a traditional capacitor bank and PF correction

    Well, I understand that you have your reasons to decline the job. I would have explained to the customer all the things that could go wrong, i.e. added complexity and cost, little savings (depending on their facility), extra point of failure in the system, little quality of available solutions...
  3. VMMF

    How much better are voltage optimizers compared to a traditional capacitor bank and PF correction

    Thank you so much for sharing this real life experience. I'm growing very concerned because I see there are now 5 parallel tenders to install these Nola devices on 5 different schools and my concern is that they may have previously run a pilot project on some initial school which showed...
  4. VMMF

    How much better are voltage optimizers compared to a traditional capacitor bank and PF correction

    So from your explanation I see the FLA rating is for the combination of load + magnetizing current (resistive + reactive) where the reactive barely changes depending on the load and the resistive changes a lot. The voltage required to move the motor is proportional to the load + magnetizing...
  5. VMMF

    How much better are voltage optimizers compared to a traditional capacitor bank and PF correction

    Are you saying that if a motor is rated with a service factor of 1.15 which makes its wingdings resistant to more current for a brief time it still will only consume the nominal FLA? If a motor maximum voltage supply is limited, the maximum current will be limited right? Just like a star-delta...
  6. VMMF

    How much better are voltage optimizers compared to a traditional capacitor bank and PF correction

    Thank you for introducing me to the Nola concept! I see what you mean. They were saving on baseboard heating electricity but not considering the extra oil cost that they would require for their furnace
  7. VMMF

    How much better are voltage optimizers compared to a traditional capacitor bank and PF correction

    My provincial government just opened 3 tenders to provide voltage optimizers for 3 schools. I've been reading a bit about them and I really don't foresee many benefits. I consulted these links: Short length article Medium length article Long article These were the essential ideas from the...
  8. VMMF

    Wye-Wye Transformer and grounding

    Questions 5,6,7,and 8 that I made have been ignored so far. I think they were overlooked with so much activity in this thread. Could anyone please reply them in order? Thank you
  9. VMMF

    Porcelain vs polymer housing Metal-oxide station class surge arresters (2021 comparison)

    Thank you for your answers. @ Rejeckted excellent! @ RRaghunath I have the same doubt as cranky108 @dpc. What do you mean better survival rate when shot? Vandalism? @davidbeach If porcelain lightning arresters are sized with enough Pressure Relief Capability-Symmetrical rms (kA). Do they still...
  10. VMMF

    Porcelain vs polymer housing Metal-oxide station class surge arresters (2021 comparison)

    @RRaghunath Thank you for your answer. So Silicone rubber is actually better than porcelain in every aspect mentioned in my question? What possible reason has the utility company to continue using porcelain then?
  11. VMMF

    Wye-Wye Transformer and grounding

    @davidbeach . Thank you for your answer. I'm not sure if you were answering my question #8, which is, if we have a wye grounded-wye grounded transformer, does a fault on primary side will trip relays on secondary side? I know secondary side faults are visible on primary side, but does primary...
  12. VMMF

    Porcelain vs polymer housing Metal-oxide station class surge arresters (2021 comparison)

    I'm writing the specifications for a new substation class transformer that needs to be purchased. As a guideline, I'm using the specifications written by our provincial utility company for a similar transformer that was bought by them. On the lightning/surge arresters section they specify...
  13. VMMF

    Wye-Wye Transformer and grounding

    @RRaghunath Great post. I would like to ask you 5. On delta(pri)-wye grounded(sec) systems if we have a phase-ground fault on the secondary, fault current will flow from phase -> ground -> neutral of the secondary transformer? 6. Could you please provide some links or name articles further...

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