smart screen question

[csfPickard]

10 x 60w flourescent lamps will have an assumed current demand at 230v of

a-2.6a

b-4.35a

c-4.7a

d-7.83

i found this question on smartscreen and the answer it says is 4.7amp

am i missing something because i thought the answer was 2.6amp

I=P

V SO 600 DIVIDED BY 230 = 2.6

HELP

 

[a1]

4.7A

Assumed current demand

10 x 60 x 1.8 / 230 = 4.69A rounded to 4.7A

 

[a1]

Don't forget they are Fluorescent Lamps and to include the current on start up too, that Is where the correction factor of 1.8 comes from.

HTH.

 

[csfPickard]

ok brilliant thanks

so the pf for all flourescent lights would be 1.8?

 

[ElecQ]

It's not so much power factor directly, more an allowance for the inductive nature of discharge lighting and the higher start up currents.

I still equals P/V as you have done, but in this instance a "factor" of 1.8 is assumed to cover the excessive start up currents and inductive load.

You might be thinking of P=V x I x cos0 (theta) which is not the case for this particular question.

 

[Andy™]

ok brilliant thanksso the pf for all flourescent lights would be 1.8?

power factor is only 1 or less. and rarely 1.

the 1.8 is the corection factor. during startup, they will draw more power than they use in normal use, so you have to times current by 1.8