Contact us for an immediate quote at

Indoor 3-Stage Lightning Surge Protector for RS-232 Sensors & Control Lines




Import duties, taxes and any additional delivery or clearance charges, are not included in the item price or the quoted shipping cost. These charges are the responsibility of the Buyer.

Please check with your local customs office to determine any additional charges prior to purchase.

Continue Shopping or View Cart

The HGLN-D2 series of high performance 3-stage lightning protector provide superior protection of differential or balanced digital or analog lines from transients and surges. The units will protect two pairs of differential data or analog signal/control lines.

The first stage is comprised of a differential gas discharge tube. Stage two is a pair of current limiting series resistors and the final stage is a low capacitance diode array. The use of three terminal differential gas discharge tubes provides superior common and differential mode protection against conducted transients versus the use of lower cost two terminal tubes. The second stage series resistance limits the power dissipation of the fast diode clamp array in the third stage. This allows time for the slower but higher power gas tubes to flash over. The diode array clamps the leading edge of fast transients to safe levels until the high power gas tubes turn on. This eliminates the damaging leading edge spike that single stage gas tube protectors let leak through. The diode array's low capacitance assures that the suppressor will not degrade the high-speed signals. The 3-stage design can handle higher-level transients than a protector that uses only diodes.

For more complete surge protection of data lines, the use of two units is recommended, one at each end of the line.

For outdoor applications, this protector is also available in a weather resistant enclosure. See AL-D2W-12. For additional information and complete specifications, see data sheet below.


  • Industrial grade
  • 3-Stage surge protection
  • Cast aluminum construction, integral mounting feet
  • Protection of digital or analog signal or control lines & provision for shielded cables
  • Superior to diode or TVS only based designs