Surge Protection for NEMA TS2 Cabinets

Traffic Signal Lights - Butler, PA

Overview of NEMA TS2 Cabinet

Appeared in 1989, NEMA TS2 Cabinet replaced the original NEMA TS1 cabinet. With more performant controllers and upgrades such as Malfunction Management Unit (MMU),test switches within the loop amplifier rack, they also drastically simplified the installation and mainenance by reducing the wire congestion of the I/O back panel. This was mainly achieved through the use serial ports of communication. SDLC (Synchronous Data Link Control)and BIU (Bus Inteface Unit) found a new home in the transportation indutry.

NEMA TS2 are the cabinets presently the most depoyed and controlling most of the intersections nationwide and still present in most of the DOTs and munucipalities specifications.

Threat to NEMA TS2 Cabinet

With the icnreased presence of sensitive electronics, the NEMA TS2 cabinets became even more sensitive to electrical transients. This is why a most manufacturers have implemented a global surge protection mitigation systems to keep their equipment running at all time and avoid "dark" intersections. Loss of power or equipment leading to a lack of proper signalization at a cross road, is one of the primary cause of accidents and human injuries or death. Although traffic cabinets may use SPDs to protect the system, the majority of the surge solutions presently deployed in the TS2 traffic cabinets creates a disprution of that power continuity to the cabinet are safety concern.

Nema TS2 Cabinet

The solution for NEMA TS2 Cabinets

CITEL recommends the use of parallel installed SPDs, to ensure that power is being supplied to the traffic equipment in all conditions. This reduces the risk of the "dark" intersection, without any signalization, main cause for accident. Surge protection plays a vital role in preserving the integrity of equipment and, more importantly, protecting the lives of personnel.

The installation of Surge Protective Devices (SPDs) within the traffic controller cabinets is a measure that will not only extend the life of the circuit components but also increase the reliability of the system as a whole.

Selecting an SPD for NEMA TS2 Cabinets

NEC/NFPA 70 require that Surge Protective Devices (SPDs) shall be UL1449 Listed . This means selecting a surge protector is easier than it has ever been. There are only a few choices available for SPDs that are UL Listed for any of the most commonly used surge standards including UL1449 5th Edition, UL497B, and UL497E, in addition, only UL Listed Surge Protectors are acceptable for facilities that will install a Lightning Protection System (LPS) certified to either NFPA 780 or the UL96A Master Label.

Recommended SPD for Main Service Panel

LocationEquipmentSystemSurge Protector Model#Link
Main Service Pedestal120/240Vac M50-120T-A M50-A

Recommended SPD for TS2 Cabinets

LocationEquipmentSystemSurge Protector Model#Link
Power Panel120Vac DS72US-120S/G-F-ASSM

Cabinet Power Supply120Vac
Power Input
DS72US-120S/G DS72US-120S/G

Cabinet Power Supply24Vdc
Cabinet Power Supply Output
DS220S-24DC DS220S-24DC

Cabinet Power Supply12Vdc
Cabinet Power Supply Output
DS220S-12DC DS220S-24DC

Vehicle Detection CameraPOE+ MJ8-POE-C6A MJ8-C6A

Bus Interface Unit (BIU)RS485 DD25-24V

Contact us to develop a surge mitigation solution for your application

Where to purchase Citel SPD's


1ANSI C62.41, Low-Voltage AC Power Circuits
2UL1449 4th Edition, Surge Protective Devices
3UL1449 5th Edition, Surge Protective Devices
4UL497B, Surge Protectors for Data Lines and Fire-Alarm Circuits
5UL497E, Antenna Lead-in Conductors
6IEC 61643-11, Low-Voltage Surge Protective Devices - Part 11: Surge Protective Devices Connected To Low-Voltage Power Systems - Requirements And Test Methods
7IEC 61643-21, Low Voltage Surge Protective Devices - Part 21: Surge Protective Devices Connected To Telecommunications And Signalling Networks - Performance Requirements And Testing Methods
8IEC 61000-45, Electromagnetic Compatibility (EMC) - Part 4-5: Testing And Measurement Techniques - Surge Immunity Test
9CSA 22.2
10NOM-001-SCFI, Standard for Electronic Equipment
11NOM-003-SCFI, Electrical Products - Safety Requirements