Lightning protection


    Maximum operating voltageUp to 24 kV
    Protection typeAgainst direct & indirect lightning
    Installation3 products per pole
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    SAd21z is intended to ensure protection of:

    • Recloser and Load Break Switches

    • Medium- and Low-Voltage Transformer

    • Underground Cables

    • Conductor and insulator against direct and indirect lightning strikes, installed on Section- and Termination Poles.

    The SAd21z installed in association with Metal-Oxide-Arrester provides the best possible protection for distribution substations against lighting activity.

    Operational Principle

    The Operational Principle is based on the EasyQuench Technology.

    The variable length of electrodes and different attachment solutions makes the SAd21z adaptable to any type crossarm installation.

    Overall Dimensions

    Medium sad20z 3

    Performance specification and characteristics

    SAd21z and the line
    Highest voltage for equipment

    up to 24 kV for:

    • 3W systems with insulated, compensated neutral.

    up to 21 kV for:

    • 3W and 4W systems with solidly grounded neutral;
    • Lines with overhead shielding/ground wire.
    Maximum prospective fault current*, kA 5
    Rated frequency, Hz 50 (±12)
    Power frequency withstand voltage (for minimal 140 mm air gap), kV
    SAd21z and lightning
    High current impulse (4/10 μs), kA 65
    Lightning discharge capability** (200 μs), C 2.4
    Maximum fault quenching lightning current (8/50 μs), kA 20
    Minimum withstand amount of operations 10
    Additional power losses on the line, % 0
    Weight, kg 3.5
    Average life time expectancy, years 20 to 30
    UV resistance***, h 1000
    Time to install/pole, min. 10 to 20
    Maintenance 1 visual verification per year
    Additional Equipment cross-arm fitting and conductor clamp + jumper

    * Maximum calculated short-circuit current in LLPD’s location;

    ** According to IEC 60099-8;

    ** According to ISO 4892-2, method A, IEC 62217.


    1 piece per phase each circuit on one pole for ensuring comprehensive protection of an overhead line against DLS, BFO and IOV.

    LLPD SAd21z must be installed with an air gap between its electrode and horn electrode. In order to select the proper value of the gap, please address to the table.

    Insulator’s CFO (kV)

    SAd21z: Air gap (mm)

    6 to 17 kV Highest voltage for equipment

    18 to 24 kV Highest voltage for equipment


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    Medium sad20z   3

    Test Certificates

    Type of Test
    Standard Lightning Impulse Sparkover Test STREAMER
    Follow Current interrupting test STREAMER
    Vibration Test STREAMER
    Functioning Test STREAMER