Overview

Bourns® Model 1800 Series Signal and Dataline Protectors are designed to protect sensitive electronic circuits and components from damaging
surge voltages and currents. Their extremely fast response and low clamping voltages make them particularly suitable for the protection of
signal and data lines associated with computer, data communication, instrumentation, broadcasting and industrial controls. They may be used
directly with EIA standard interfaces RS-232, RS-422, RS-423, RS-485 and with 20 mA and 50 mA instrumentation loops. The Model 1800
Series Signal and Dataline Protectors are fast, rugged and capable of protecting against fast rising voltage transients as well as the severe
current surges associated with lightning discharges.
Method of Operation
Bourns® Model 1800 Series are heavy-duty, multi-staged protectors. A solid-state section intercepts the leading edge of the surge with subnanosecond
response time. Within microseconds a 3-pole common chambered gas tube capable of handling 20,000 ampere lightning
currents operates and crowbars the surge to ground. The protector remains in the crowbar state until the surge has passed and line voltages
return to safe levels, then automatically restores the line to normal operation. There is no need for resetting a breakeror replacing a fuse.
Application
Protectors are generally placed at each end of a signal or data line or current loop. In the case of daisy-chain confi gurations (such as RS-485),
protectors are placed at each node. The 1820 models provide both line-to-ground and line-to-line protection and are designed to use on differential
signals (such as RS-422 or RS-485) and 4-20 mA current loops. 1810 models provide line-to-ground protection for two separate circuits
and are designed for use on ground referenced signals (such as RS-232) where the return wire is grounded at the protector. The 1811 and 1821
models provide the same protection modes for high frequency applications.
Related Bourns® Protectors
For outdoor applications with 1/2 inch NPT ports (such as fi eld-mounted 4-20 mA transmitters), please refer to Bourns® Model 1669 Series
Protector. In this application, the mixed use of a Model 1800 Series Protector at the controller and a Model 1669 Series Protector at the fi eld is
recommended.