Whether you control a process with a computer, a process control system, a PLC, or a field device, a surge protector can eliminate or reduce the risk of damage to sensitive electronics caused by transient overvoltage. In this article, we outline three surge protection solutions—for signal lines, for supply lines, as well as for Fieldbus and Ethernet-APL applications.

Surge Protection for Signal Lines

Modules for DIN Rail Mounting

The M-LB-4000 surge protection system is a modular assembly, consisting of a base and a protection module. The base modules are mounted on standard DIN rail, into which the protection modules can be easily inserted. This enables simple and tool-free installation, as well as quick replacement of individual modules during operation, without any interruption of the signal circuit. If a protection module is removed and reinserted while turned 180°, the signal circuit is interrupted by an integrated disconnect function, the so-called loop disconnect function. This enables isolation tests and loop checks during commissioning. With a width of only 6 mm, the M-LB-4000 modules reduce the space required in the switch cabinet to a minimum. The surge protection system also offers reliable self-monitoring via an indicator window when the protection module needs to be replaced. An error detection module can be used to forward the status information directly to the control level and to the integrated display. This simplifies maintenance and reduces operating costs.

The modules from the M-LB-2000 surge protection system are also mounted on a standard DIN rail, without the need for tools. When the module is plugged in, a loop disconnect is achieved via two switches on the module, making fault repair and maintenance work easier. The M-LB-2000, which is only 6 mm wide, not only saves a lot of space in the switch cabinet, it practically replaces the terminal block while also offering surge protection. This means that knife disconnect terminal blocks can be dispensed with completely. The certificates range from ATEX, IECEx, and UL for Zone 1 and Div. 1 intrinsically safe loops, as well as SIL 3. M-LB-2000 modules are available with either screw terminals or spring terminals with push-in connection technology.

Plug-In Modules for the K-System

The P-LB* plug-and-play modules save space in the switch cabinet and reduce the wiring effort, since they can be directly plugged into the 20 mm wide isolated barriers of the K-System. The surge protection barriers have been specially developed for this application. With their snap-on fixing method, the plug-in modules snap directly onto the terminal block and can be removed just as easily. This means installation and regular maintenance tasks can be carried out very quickly.

Screw Modules for Field Devices

With the type F*-LB screw modules, the surge protectors are attached directly to the field device, without the need for additional external wiring. The surge protectors have a rugged metal housing with IP67 degree of protection and can be used in hazardous areas. The modules are available with different types of thread, making them suitable for use with a correspondingly large number of field housings. The available thread types include ½ NPT (NPT creates a seal that keeps moisture outside the thread), PG13.5 (standard for cable entries), and M20 x 1.5 (ISO standard).

Surge Protection for Supply Lines

Type M-LB* modules for supply lines can be plugged in and mounted on the DIN rail. Type 2 surge protectors are available for protecting all standard mains configurations for 125 V AC and 230 V AC. In addition, Type 3 surge protectors for 230 V, 120 V, and 24 V supply lines are available to protect control panels or other sensitive electronics. The M-LB*surge protectors can be easily replaced without tools during operation.

Surge Protection for Fieldbus Applications and Ethernet-APL

In the field and in the control room, measurement and control signals of the fieldbus infrastructure as well as the entire instrumentation must be reliably protected against overvoltages. FieldConnex® surge protection modules are designed for applications according to the PROFIBUS PA and FOUNDATION Fieldbus H1 fieldbus standards. They are also available with optional self-diagnostics. The diagnostics-capable Segment Protectors and field barriers with surge protection modules indicate the end of their useful lifetime in the control room with the help of advanced diagnostics: an error message indicates which track is affected. Based on the LED on the device, the maintenance personnel on site can see which module needs to be replaced. Existing FieldConnex® Segment Protectors (R2-SP*, F2-SP*, or F.SP5*) or field barriers (R4D0-FB* or F.FB1*) can be retrofitted with suitable surge protection modules. These are simply plugged onto the Segment Protector or field barrier without the need for any additional wiring.

Mountable on a DIN Rail, surge protection modules for Ethernet-APL also serve as a connection point for bringing in cables from the field. As for any other infrastructure described in this article, there are modules that can be mounted in the field device instead of the cable gland.

Pepperl+Fuchs offers a complete product portfolio for surge protection. Suitable surge protection devices are available for signal and supply lines as well as for fieldbus infrastructure and Ethernet-APL. The modules reliably divert surges to the ground, thus protecting people and equipment.

More Information

• Surge Protection from Pepperl+Fuchs
• M-LB-4000 Surge Protection System for Signal Lines