# triphase mesure

3 replies to this topic

### #1 fred

fred

Junior Member

• Members
• 3 posts

Posted 09 January 2003 - 08:19 PM

hi! i'm a new user?

On a single-phase line one calculation the dephase between the tension and the current in order to determines the power-factor.
I seek has to know how to deduce the power-factor on a three-phase line. Does one have to measure dephasing on each line and then which operation must one forward there?

thanks!!!!!

### #2 TheOne

TheOne

Junior Member

• Members
• 2 posts

Posted 11 January 2003 - 09:11 PM

I am assuming that you are referring to the phase angle between the voltage and the current and are using a scope. If so, power factor measurement on a three phase line would be similar if there are no seperate, single phase loads involved.

### #3 fred

fred

Junior Member

• Members
• 3 posts

Posted 12 January 2003 - 03:49 PM

If however the inductive load is unbalanced what must make

there is a mathematical operation used ?
or whatever!!!

### #4 marke

marke

Posting Freak

• Moderator
• 2,604 posts
• Gender:Male
• Location:Christchurch, New Zealand

Posted 17 January 2003 - 07:33 PM

Hello fred

By definition, power factor is the ratio between KW and KVA. If you have sinusoidal current and voltage (no harmonics) then this equates to the cosine of the angle between the current and voltage so on a single phase system, you can measure this angle to get the power factor.
On a balanced three phase system, you can make this measurement on each phase and average the result. On an unbalanced system, you need to measure the total KW and divide this by the total KVA to get a meaningful result.

Best regards,

#### 0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users