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Negative Phase Current

Electronic energy meters can have various additional useful functions for tamper protection, event logging or billing. The screenshot below was taken from our four-quadrant simulation. Other names used in literature are Reversed Phase Current or Reversed Power Flow.

Principle for negative phase current detection


The electronic energy meter monitors constantly the direction of current flowing through each phase. When a specific phase current is detected to be flowing reverse, a event for negative phase current is set for each phase individually.


Default logic

When the current direction in one phase is different from current direction of two other phases and all currents are above the current threshold parameter, meter starts a timer. If such condition stays for a time period longer than Reverse power flow time threshold, the meter triggers a reverse power flow condition.

When later all currents start flowing in same direction or at least one of the currents falls below threshold, meters starts a timer again. If same condition stays for a time period longer than Reverse power flow time threshold, the meter detects normal phase sequence condition.
Reverse power flow condition is registered via dedicated events in tamper log book and tamper alarm on display is set.

This function can be disabled.
Disabling the function is necessary when the customer is feeding-back power to the grid, e.g. in case of solar installations.

The logic behind the negative phase current detection can be customized.

Thank you for taking a look.
You can leave a comment below.

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6 Replies to “Negative Phase Current”

  1. If the load supply switching off then how showing reverse in PQA L1- 0.00 kW , L2 -0.00 kW , L3 o.1 kw if there is no load it should not show reverse flow accordingly

    1. If you switch off the load, your analyser can’t measure current. Power analysers need a certain minimum current to indicate power. So, -0.00 kW can also be +0.00 kW. I assume that the analyser is connected to phase L3 and has a consumption of 100 W. Check the specifications of your instrument for minimum current and switch-on one consumer to meet the minimum currents in all 3 phases.

  2. Dear sir i already checked to use power quality analyzer the flow is showing reverse on two phases L1 L2 and some time in all please can you tell me the reason.
    The connection of meter checked and verified its proper nothing found wrong with connection

    1. It’s hard to say without having more details. Sounds like magic, you are delivering power to the grid. If you have the possibility, check the export registers of the meter, only to avoid that the power quality analyser delivers false information.
      If you have heavy rotating masses like huge electro motors, you have a temporary reversed current until the motor stops rotating after switching off.
      I suggest monitoring all consumers individually to narrow the problem.
      Keep us informed, it’s interesting.

  3. Why the smart meter is showing reverse flow while connected properly and there is no solar panels etc

    1. The meter detects the flow direction of the current. Seems that your meter has inverted connections. That doesn’t harm the functionality, but better inform your energy provider. They have tools to check the flow.

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