Current leading voltage

Discussion in 'General Electronics Chat' started by gbs59, Oct 6, 2010.

  1. gbs59

    Thread Starter New Member

    Oct 6, 2010
    I have a small building fed from a 3 phase 4 wire wye transformer. The load is small. Most of the load is 120 volt single phase. The building is a dormitory. The load is lighting electronic ballasts,120v fractional HP motors small refridgerators,Pcs, tvs, college student stuff. There is a very minimal amount of 3 phase motor load. The question I have is as follows. My sub metering shows a very small angle current lagging voltage one phase there is almost no angle and current will lead voltage or bounce to lagging. Does this sound normal?
  2. timrobbins

    Active Member

    Aug 29, 2009
    Sounds likely, depending on how your meter is taking measurement. You would have leading and lagging contributions from lighting capacitors and motors, and distortion from smps loads, with no load being over dominant.
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
    You're just seeing the effect of inductance in the loads and it's totally normal. The only time this gets out of hand is when you're driving mainly reactive loads, in which case a PFC capacitor of a calculated KVAR rating is added to the mains.

    You're actually using a little more power than what you're being charged for, the power meter measures KW hours and the electic company ignores the effects of power factor unless you're using a ton of power as in a large industrial building.