ELF 2 Phase Detector

Toolset for phase recognition in LV networks, operates under load condition without interruption.


The innovated tool set ELF 2 is used to determine phase order in low voltage networks (230/400V) with continuous uninterrupted operation. The set contains two devices for sending and receiving of synchronization signals. Booth devices are powered directly from the measured network and do not need any additional setup to cooperate. With one sending unit, multiple receivers can cooperate at once. The correct operation is indicated with LED diodes.


  • for phase identification in low-voltage power distribution grids
  • based on transmission of synchro- pulses between transmitter and receiver over power line
  • set contains transmitter and receiver
  • both units powered from measured line
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    Operation and Basic Principles


    The transmitter connects blue wire with croco clips the N or PEN conductor in the MV/LV cabinet transformer stations or other suitable place of low-voltage distribution. Then connect the black wire with clips to the phase conductor voltage L1 (or wire which we denote as L1 if the connected site does not yet have determined phases). If everything is correct, the green LED (PWR) will indicate the presence of the measured voltage (230 Vrms). If the LED is not lit the voltage is not present or fuse inside the unit tripped. One second interval flashing of the yellow LED (Tx) indicates broadcasting of synchronization pulses. When disconecting for safety reasons first switch the unit off and then disconnect the phase and neutral.


    The receiver first connects its blue wire with croco clip to the N or PEN conductor in the measured location of low-voltage distribution network. Then connect the black wire with croco clips connects to the measured phase conductor where we want to determine the actual phase order. If everything is correctly connected and the instrument is powered the green LED (PWR) lits. Also in a second long intervals one of the three red LEDs (L1, L2, L3) flashes to indicate phase sequence L1 transmitter.

    If the instruiment can not determine the phase order (phase shift of the measured phase is greater than +/- 20 ° from the phase of the transmitter) all three red LEDs (L1, L2, L3) flashes briefly. When the sync pulse is not correctly recognized (weak signal from the transmitter, due to large distances from the transmitter or high level of noise in the receiver) yellow LED (Err) flashes in 2 second intervals. In this case it is possible to move the transmitter to the already known or designated point of measurement network, which is closer to the measured place and restart the detection procedure. When disconnecting please first switch off the instrument for safety reasons and then disconnect the phase and neutral wires.