Plug in protectors used with an interface(pg 8) suppress transient overvoltages on data lines, analog loops and telephone lines operating in hostile electromagnetic environments. SuppresSurge Plug In Protectors utilize the classical 3 element, high energy, primary overvoltage protection cicuit on a printed wiring board. Four separate circuits per board allow four lines of protection on the 232B, TEL50B, TEL185B, and CLPSB's. On the 422B, 485B, and 420LB series, additional line to line protection is added resulting in two pairs (loops) of protection circuits per board. The protector has a board edge of free edge connector with spacing for a 1500 Vdc minimum breakdown voltage allowing the gas discharge tubes to reach firing voltage without arc over. The edge connector has copper foil on only one side of the board to preclude backwards installation. All plug in protector boards are conformally coated to prevent direct electrical contact with the circuits. The circuits have a rugged 10,000 Amp (10 kA) 8/20 us single impulse rated GDT on the input and a rapid response 1500 W peak pulse power bidirectional TVS diode on the ouptput. In most cases, the circuit unput and output are isolated with a 1/2 Watt ten ohm carbon composition resistor allowing a conservatively rated operating line current of 100 mA. In high current versions, the ten Ohm resistor is replaced with and inductor permitting a two or five Ampere operating line current.

How to Choose a Protector

For RS232, RS422 or RS485 data lines select the associated product, i.e., 232B, 422B or 485B respectively. For 4-20 mA loops, select a 420LB protector with a voltage rating equal to or greater than the system maximum operating voltage. For telephone lines, select a TEL50B for digital lines with an operational voltage of 48 Volts dc; select a TEL185B for an analog system having the 90 Vrms ringing voltage superimposed upon the 48Vdc central office supply voltage. For high current applications, such as valve control lines, a 2 Amp(2000 mA) or 5 Amp(5000 mA) rated CLPSXXXB with the required voltage rating can be selected. The 5 Amp CLPS has two lines per board and is supplied with crimp jumper terminals to paralled connect two adjacent wire screw clamp interface circuit paths. Note that high current plug in protectors are intended for use with interfaces with adequate current capacity i.e., wire screw clamp or solderable terminals.