FAQ n° 12359
Utilisation des appareils
Analyseurs de puissances, d'énergies, de pertubations
Pinces AC série B
Question
Asked on
11/19/15
How should I interpret the Vunb parameter present with the Fresnel diagram on my Qualistar+?
Response
Answered on
11/19/15
The Vunb parameter can be used to qualify the level of unbalance on a three-phase network.
To calculate the unbalance Vunb, the instrument takes into account:
- The unbalance due to the values of the three phases
- The pahse shift between the three phases
- Correct connection of the three phases- Formula:
Where Vunb is the unblance, Vi is the negative phase sequence and Vd is the positive phase sequence of the three-phase network. If Vunb = 100%, it means that:
- One phase is disconnected
- Two or more phases are inverted
- Several of the Qualistar+ voltage inputs are on the same phase