Image credit: Surge Suppression Inc. | L-com Inc. | Huber + Suhner AG
Dataline and DC surge suppressors protect equipment from voltage transients on data and direct current (DC) signal lines. Because voltage surges and spikes can damage communications boards and corrupt data, it is especially important to limit or eliminate transients in data or DC systems.
Surge protectors intended for data lines are unique in that they may be unique products or may be built into a consumer-oriented AC power surge suppressor. For example, the product below includes eight outlets for AC power devices as well as an input and output to protect a phone or Ethernet data line.
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For general information about surge suppressor principles, general specifications, and standards, please visit the Surge Suppressors Selection Guide.
Surge suppressors may be manufactured as single stage or three stage devices.
Single (left) and three stage protection circuits. Image credit: B&B Electronics
Single stage surge suppressors represent the majority of products produced and consumed, and are capable of protection against routine overcurrents. A single stage device simply includes a single method of shunting overcurrent, most often a metal oxide varistor (MOV). If the devices ground connection is solid, the suppressor will be capable of handling most transients.
More advanced surge suppressors designed for protection against higher voltages may include three stages for shunting and clamping voltage transients. In the above circuit schematic, overcurrent is first routed to a gas discharge tube, which safely shunts very large overcurrents, albeit slowly. This slow conduction is offset by the final two stages: a resistor which limits the amount of current to the third stage, and a transient voltage suppressor which clamps the voltage to an acceptable level. The final TVS stage is designed to prevent damage to the protected device until the gas tube begins conducting at an acceptable level; at this point the tube conducts and safely shunts all overcurrent.
Buyers of surge suppressors must take care to match the product's prescribed specifications to those of their desired application. For example, a product's maximum surge current must be high enough to accommodate the predicted overcurrents on the system the device will protect. A suppressor's number of protected lines is also an important specification for dataline surge suppressors; because communications networks often have many signal lines, buyers should be sure that a surge suppressor can accommodate all signal lines.
A dataline / DC surge suppressor may feature one of several mounting options.
Wall / panel / backboard mount devices include mounting holes for fastening onto a flat vertical surface.
DIN rail suppressors mount on metal rails standardized by the Deutsches Institut für Normung, a German standards body. Common DIN rail widths include 15 mm, 35 mm, and 75 mm.
Plug-in suppressors are modules that attach to an existing surge suppressor or system.
PCB mount devices are directly soldered onto printed circuit boards (PCB).
Rack mount devices slide into equipment racks, often a standard 19" telecommunications rack.
For information about surge suppressor connectors, please read the Surge Protective Devices (SPD) Selection Guide.
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