Determing three phase amps

[arnettda]

As per 220,87 I have contacted the POCO and found out the max demand on a 3 phase service is 53 KW.
Using the formula Watts = Voltage X current x 1.73 I come up with 127.64 amps
Am I correct?
Do I need to use POCO power factor when I do this formula.

I have a 320 amp continus meter pedestal so I can load that to
240V times 320A times 1.73 which would be 132 KW
Again am I doing this correctly.
I find many formulas that mention using the power factor but am having a hard time obtaining this from the POCO

This is High Leg 3 phase system so my voltage 240V phase to phase.
Thank you

 

[adamscb]

Voltage X current x 1.73

​

Multiply the above by the utility pf and that will equal Watts. The above equation alone is equal to Volts-Amperes (VA). To go from VA to Watts you multiply by the pf. ​

 

[MRKN]

adams math is correct. To add on to his comment, the utility is not going to tell you your pf, your load that you install will dictate that. For residential service the will not penalize you for a low pf since it is typically a non-issue. When you say you have a certain kW load, that is an incomplete picture. Where are you getting this data from? A nameplate? A panel schedule? If all your loads are resistive and you have no rotating machinery then it's more or less accurate to say your pf = 1 and your W = VA. However if you have any induction motors your pf will be slightly lagging which means in the range of .8 - .99, depending on the total mixture..

 

[Besoeker]

adams math is correct. To add on to his comment, the utility is not going to tell you your pf, your load that you install will dictate that. For residential service the will not penalize you for a low pf since it is typically a non-issue. When you say you have a certain kW load, that is an incomplete picture. Where are you getting this data from? A nameplate? A panel schedule? If all your loads are resistive and you have no rotating machinery then it's more or less accurate to say your pf = 1 and your W = VA. However if you have any induction motors your pf will be slightly lagging which means in the range of .8 - .99, depending on the total mixture..

And, just to add to that.............
Pretty much any of the load that is electronic or non-linear will have a lower than unity power factor. Televisions, computers etc. Again, the POCO can't advise about that.

 

[arnettda]

adams math is correct. To add on to his comment, the utility is not going to tell you your pf, your load that you install will dictate that. For residential service the will not penalize you for a low pf since it is typically a non-issue. When you say you have a certain kW load, that is an incomplete picture. Where are you getting this data from? A nameplate? A panel schedule? If all your loads are resistive and you have no rotating machinery then it's more or less accurate to say your pf = 1 and your W = VA. However if you have any induction motors your pf will be slightly lagging which means in the range of .8 - .99, depending on the total mixture..

My KW load comes from the power company. It is the Max demand load for the last 5 years.

 

[arnettda]

And, just to add to that.............
Pretty much any of the load that is electronic or non-linear will have a lower than unity power factor. Televisions, computers etc. Again, the POCO can't advise about that.

My loads are pretty much refrigeration , air conditioning , and electric oven loads. It is a butcher shop with a kitchen that serves food and does a lot of catering.

 

[electrofelon]

And, just to add to that.............
Pretty much any of the load that is electronic or non-linear will have a lower than unity power factor. Televisions, computers etc. Again, the POCO can't advise about that.

Although IMO, 220.87 does not require taking power factor into account.

 

[kwired]

Although IMO, 220.87 does not require taking power factor into account.

No but nearly everything in Art 220 is done in VA.

If POCO is capable of giving VA instead of W, that would be the better way to do this. One must also remember that net VA or W value will not give you the highest loaded line for unbalanced loading conditions. 120/240 volt high leg delta especially are often subjected to more unbalancing - unless the majority of load is three phase loads.

 

[Iron_Ben]

No but nearly everything in Art 220 is done in VA.

If POCO is capable of giving VA instead of W, that would be the better way to do this. One must also remember that net VA or W value will not give you the highest loaded line for unbalanced loading conditions. 120/240 volt high leg delta especially are often subjected to more unbalancing - unless the majority of load is three phase loads.

Extremely good point about the potential imbalance in phase currents in a delta service with significant single phase loads. We (POCO) served a medium sized small town “Piggly Wiggly” grocery store built in the early 60’s. Load grew incrementally over the years and there was trouble. I had a guy amp the phase conductors on a blazing hot day and they were something like 450, 460, and 100 on the stinger. A *far* cry from what one would calculate knowing the three phase load and assuming balanced currents.

 

[Jraef]

Probably your biggest loads in a butcher facility will be refrigeration and A/C, those will all be motor loads. The accepted “conventional wisdom” is to assume a .8 power factor overall in trying to estimate Amps from kW when your loads are mixed.

 

[kwired]

Probably your biggest loads in a butcher facility will be refrigeration and A/C, those will all be motor loads. The accepted “conventional wisdom” is to assume a .8 power factor overall in trying to estimate Amps from kW when your loads are mixed.

Being on high leg system however we can't assume how balanced the load is across all three phases.