Surge Protective Devices (SPDs)

Surge protective devices (SPDs) are designed to protect equipment against temporary excess voltage and/or current. They differ in terms of signal protection type. Dataline and DC signal surge suppressors protect against transient overvoltages on data or DC signal lines. Single-phase surge suppressors protect equipment from transient overvoltages on single-phase AC power lines. By contrast, three-phase surge suppressors protect equipment from transient overvoltages on three-phase AC power lines. Other types of transient voltage surge suppressors are also available. 

Selecting surge protective devices (SPDs) requires an analysis of performance specifications such as maximum surge current, AC energy absorption, DC energy absorption, maximum AC power, maximum DC power, and operating temperature. Maximum surge current is the maximum current allowed for a single impulse waveform with a continuous voltage applied. Both AC energy absorption and DC energy absorption measure the ability of transient voltage surge suppressors to absorb heat energy created by transient surges. 

Surge protective devices (SPDs)  differ in terms of mounting styles and outlet or connector types. Mounting styles include wall, panel or backboard mount; DIN rail; rack mount; hard-wired or device mounted; in-line or integrally attached; plug-in module; and printed circuit board (PCB) mounted. Outlet types for transient voltage surge suppressors include standard electrical outlets; RJ11, RJ13, and RJ14 phone jacks; RJ41, RJ45, and RJ48 data jacks; screw-down terminals; DB connectors, and coaxial cable connectors.  

There are many optional features for surge protective devices (SPDs). Examples include AC adapter spacing, audible alarms, complete pin protection, continuously live outputs, graphical displays, grounding wires, and integral disconnects. Hospital grade products must pass additional safety tests that measure leakage current. Some transient voltage surge suppressors are housed within NEMA enclosures. These enclosures are rated by the National Electrical Manufacturers Association (NEMA) and designed for hazardous or non-hazardous locations and indoor or outdoor use. 

There are several standards, approvals, and certifications for surge protective devices (SPDs). Ratings from Underwriters Laboratories (UL) include UL 1449, Second Edition; UL 497A, UL 1459, and UL 452. Products that bear the UL Mark, the CE Mark, or the CSA Mark are also available. CE marking indicates that a product complies with the essential requirements of relevant European Union (EU) directives that uphold national standards for health, safety, and environmental protection. Transient voltage suppressors that bear a CSA Mark have been tested by the Canadian Standards Association (CSA).

• Properly Applying SPDs in a Health Care Facility (.pdf)
  Installing surge protective devices (SPDs) in health care facilities is complicated by the requirement to separate the electrical distribution among normal, essential, and emergency (i.e., critical...
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• SPD Industry Code Changes (.pdf)
  The past two years have seen many changes in codes and standards of surge protective devices (SPDs). The specific standards are from Underwriters Laboratories (UL), and the National Fire Protection...
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• Selective Coordination of Surge Protection Devices (SPDs) (.pdf)
  In 2005 changes in the National Electric Code (NFPA 70-2005) placed significantly more burden on the design of electrical systems for various types of facilities. One of the most significant is to now...
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