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

Location	Equipment	System	Surge Protector Model#	Link
	Main Service Pedestal	120/240Vac	M50-120T-A

Recommended SPD for TS2 Cabinets

Location	Equipment	System	Surge Protector Model#	Link
	Power Panel	120Vac	DS72US-120S/G-F-ASSM
	Cabinet Power Supply	120Vac Power Input	DS72US-120S/G
	Cabinet Power Supply	24Vdc Cabinet Power Supply Output	DS220S-24DC
	Cabinet Power Supply	12Vdc Cabinet Power Supply Output	DS220S-12DC
	Vehicle Detection Camera	POE+	MJ8-POE-C6A
	Bus Interface Unit (BIU)	RS485	DD25-24V

References