Whether you’re controlling a manufacturing process with a computer, distributed control system (DCS), programmable logic controller (PLC), or field device—surge protection barriers reduce or eliminate the risk to your equipment from lightning strikes and other harmful transient voltage or surge currents.
Below are four types of surge protection solutions, designed for a variety of applications. The common pattern you will see is that for field devices, you need to combine two different types of modules to provide protection. In contrast, a computer, DLC, or PLC requires only a surge protector.
1. Snap-on modules
These blue plug-and-play modules save space in the control cabinet and cut wiring costs because the wiring is self-contained inside the housing. The modules plug into the terminal block instantly and are removable for easy, convenient installation and periodic replacement. Pepperl+Fuchs offers snap-on modules that are specially designed to fit the K-System.
Snap-on modules and DIN rail mounted modules perform the same function. You can use either one depending on the size of your control room.
Using a snap-on module in combination with a screw-in module protects one control loop.
2.DIN rail mounted modules
These modules take up slightly more space than snap-on modules. Since they are DIN rail mounted, they involve slightly more wiring. They are not removable, but are instead attached to the terminal block. This means that when the time comes to replace a module, you actually have to replace the entire terminal block. If space is not an issue, and if you do not need to change them out frequently, these modules work just fine.
The DIN rail modules and snap-on modules perform the same function. You can use either one depending on the size of your control room.
Using a DIN rail module in combination with a screw-in module protects one control loop.
3.Screw-in modules for field devices
You can attach these modules right to the field device. There is no need for outside wiring. Screw-in modules come in a rugged metal housing and can be placed in hazardous location areas. These modules have different thread versions to fit into various field device housings. Available thread versions include ½ NPT thread (national pipe thread creates a seal that keeps moisture out), PG13.5 thread (standard for cable glands), and M20 x 1.5 thread (ISO standard).
Using a screw-in module in combination with either a snap-on module or a DIN rail module protects one control loop.
4. AC surge protectors
These are pluggable, hot swappable, and also mount on a DIN rail (but not power rail). AC surge protectors can be compared to a power strip. They protect AC lines coming into a PLC, DCS, or computer. One AC surge protector protects one computer, PLC, or DCS. These surge protectors can be replaced without any tools.