Applications

• RS-485 serial communications

• Modbus, Profibus and DMX applications

• 5 Volt differential or single ended data or control lines

• Industrial and building automation

• AISG control lines

Features

• Protection for up to three pair of lines plus provisions for shielded cables

• High power 3-stage surge protection, superior to diode or TVS only based

designs

• Gasketed cover and concealed mounting holes

• Removable screw terminals

• Ground clamp provided on outside of enclosure

Description

The AL-D3W-05 is a high power 3-stage lightning and surge protector that provides superior protection of differential / balanced

digital or analog lines from transients and surges. The unit will protect up to three pairs of lines or six single ended data, analog

or control lines. Provisions for use with shielded cable are provided.

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.

Failsafe Feature

The AL-D3W-05 is designed to convert into a failsafe mode in the rare case of a

catastrophic surge or lightning event. For this mode, the resistors in the second

stage will fuse and portions of the diode array will short. This effectively disconnects

the line from sensitive equipment thus limiting damage. The units are factory

repairable.

This protector features a weatherproof ABS enclosure with gasketed cover and

concealed mounting holes. Removable screw terminal strips are provided on the

input and output for convenience. To ease installation, the terminal strips can be

removed. A ground clamp provides a tie point for earth ground.