The Series 2000 Surge Suppressors are in-line protection devices designed to cover the power supply and RS-485 communication wiring between a remote sensor and a terminal processing unit. The Model 2261R4 surge suppressor is shown at right.


These surge suppressors have a three-level suppression circuit that prevents voltage and current transients from damaging the electronic interfaces. These surge suppressors meet UL, FCC, and IEC standards. A protective coating permits operation in corrosive environments. The communication signals and power supply lines are limited to 12 VDC by transient voltage suppressors (tranzorbs) to cover light and medium transients. All lines are additionally protected against highly powerful transients by high current solid-state crowbars, which respond within nanoseconds when voltage levels exceed 25 VDC and provide a full path to ground. The bypass stops when the transient fades out, and when the minimum holding current is no longer supported. A third level of protection is provided by self-resetting solid-state fuses which open-circuit the bypass after transients subside and prevent a by-pass overload to the power supply.


A power-indicating LED brightens when a minimum of 10 VDC is present and darkens with crowbar activation.


Part Numbers

  • 2261R4 – Surge Protection Boards – RTU RS485

  • 2301      – Surge Protection Board – RTU RS485 with LED Heartbeat & Bracket

  • 2301A   – Surge Protection Board – RTU RS485 with LED Hearbeat w/o Bracket

  • 2304      – Surge Suppressor – 4 Channel 4/20mA (28V)