Applications
• Load cells
• Weighbridges
• 3 and 4 wire RTD sensors
• Strain gauge sensors
• Truck stop weigh stations

Features
• Protects signal, supply and shield lines
• High power 3-stage surge protection
• Gasketed cover and concealed mounting holes
• Removable screw terminals
• Ground clamp provided on outside of enclosure

Description
The AL-LC-30 is a high power 3-stage lightning and surge protector that provides superior protection for devices such as load
cells, weighbridges, resistance temperature detectors (RTD) and strain gage sensors. These types of devices contain sensitive
and fragile components that can be easily damaged by lightning and power surges. The AL-LC-30 provides maximum protection
to the signal lines, excitation, sense lines and a shield line.
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-LC-30 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.