Applications
 4 to 20 mA sensors and controllers
 Industrial process control
 HART Street light controllers
 Toll booths, drawbridges, railroad crossing gates &
signals
 Pulse input circuits

Features
 Dual Channel
 Three-Stage Protection
 Weather resistant enclosure
 Screw Terminal Blocks
 Available in 12V, 15V and 24V models

Description
The AL-CL2-xx series are high performance 3-stage outdoor protectors that provide superior protection of
differential or common mode lines from transients and surges. These units will protect two 4-20 mA circuits.
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.
The compact weather resistant housing features a lockable hinged cover and mounting holes are provided on the
rear of the enclosure for mounting. The two cable grommets may be adjusted to cable size and are removable.