Applications

• RS-422/485 lines with AC or DC supply voltage

• Analog or IP video surveillance cameras

• Pool/spa and industrial controllers and keyboards

• Door/gate access control with RS-485 and power

• Pan-Tilt-Zoom (PTZ) camera controllers

Features

• Individual protection circuits for RS-422/485 control and power

lines

• 3-Stage protection provided for all lines

• Will work with Full or Half Duplex RS-422/485 lines

• Available in AC or DC versions

• NEMA rated enclosure with gasketed cover and

concealed mounting holes

Description

The HyperLink ALS-D25P series are designed to provide superior lightning and surge protection for RS-422/485

control and AC/DC power lines. These protectors incorporate individual protection circuits for the RS-422/485

control lines and AC/DC power lines. All housed in one NEMA rated weatherproof enclosure.

RS-422/485 Control Lines

A high power 3-stage design is used to provide protection for the RS-422/485 control line. The 3-stage design can

handle higher-level transients than a protector that uses only diodes. 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 protector will not

degrade the high-speed signals. The RS-422/485 control line is connected to the protector via its screw terminal

blocks. The terminal blocks are removable to ease wiring. The ALS-D25P series is designed to work with either 1

full duplex or 2 half duplex RS-422/485 lines.