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.
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.
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Editor's note: This article was originally published in March 2020 and has been updated for comprehensiveness.