Applications
• RS-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-485 control and power lines
• 3-Stage protection provided for all lines
• Will also protect two single ended data, analog or
control lines
• Available in AC or DC versions
• Impact and weather resistant enclosure with
locking hinged cover

Description
The HyperLink AL-D15P series are designed to provide superior lightning and surge protection for RS-485 control
and AC/DC power lines. These protectors incorporate individual protection circuits for the RS-485 control lines and
AC/DC power lines. All housed in one weatherproof resistant enclosure.
RS-485 Control Lines
A high power 3-stage design is used to provide protection for the RS-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-485 control
line is connected to the protector via its screw terminal blocks. The
AL-D15P series is designed to work with 1 half duplex RS-485 line.