Plugin style surge suppressors plug into wall outlets to protect equipment from transient overvoltages. They use shunt-type or series-type technologies, or a combination of both. Plugin style surge suppressors are designed to absorb the surge. By contract, series-type devices block the surge’s flow. Normally, shunt-type surge suppressors have a clamping voltage that approximates the circuit’s maximum safe operating voltage. To prevent equipment damage from internal or external surges, point-of-use surge devices may be used. With these surge protection devices, the equipment’s power plugs or data lines plug directly into the protected outlet.

Mounting Style and Technology

Mounting style and technology are important parameters to specify when selecting plugin style surge suppressors. Choices for mounting style 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. There are five main technologies for plugin style surge suppressors: metal oxide varistor (MOV), silicon avalanche diode, silicon thyristor diode, gas tube, and hybrid. Typically, gas tubes have higher energy capabilities than either MOVs or diodes. Hybrids incorporate features from various technologies.  

Performance Specifications

Plugin style surge suppressors carry performance specifications for maximum surge current, AC energy absorption, DC energy absorption, maximum AC power, maximum DC power, clamping voltage, and operating temperature. Maximum surge current is the maximum allowable current for a single impulse waveform with a continuous voltage applied. Both AC energy absorption and DC energy absorption measure the ability of plugin style surge suppressors to absorb heat created by transient surges. Maximum AC power and maximum DC power are also listed. Clamping voltage is the voltage at which plugin style surge suppressors conduct their full-rated current.  

Outlet Types

Outlet types for plugin style 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. Depending on the type of outlet specified, additional parameters include the number of electrical outlets, the number of RJ-type pairs, and the number of coaxial connectors. 

Standards or Approvals and Optional Features

Plugin style surge suppressors differ in terms of standards or approvals and optional features. Standards include UL 1449 Second Edition, UL 497A, UL 1459, and UL452 from Underwriters Laboratories (UL). Products that bear CE or CSA Marks are also available. Optional features for plugin style surge suppressors include AC adapter spacing, audible alarms, complete pin protection, continuously live outputs, graphical displays, grounding wires, and integral disconnects.