Weidmüller DEK 5 DIN Rail Surge Protection Device

The Weidmüller DEK 5 is a DIN-rail-mounted Type 3 surge protection device (SPD) for 24 V DC instrument and control circuits, using a combined MOV (metal oxide varistor) and GDT (gas discharge tube) hybrid technology to provide both fast-acting low-let-through-voltage clamping and high-energy surge absorption. Rated for 24 V DC nominal systems with a continuous operating voltage of 28 V DC and a maximum discharge current of 5 kA (8/20 μs waveform), the DEK 5 is designed for point-of-use protection of individual instrument loops, PLC I/O modules, and field device signal inputs in Saudi process control and DCS systems. The MOV component provides sub-microsecond voltage clamping when the transient appears, while the GDT provides the high-energy absorption path for the initial surge, resulting in a voltage protection level (Up) of less than 70 V peak — well within the 500 V impulse immunity of standard 24 V instrument loops rated to IEC 61000-4-5 Level 3.

The DEK 5 mounts directly on 35 mm DIN TS 35 rail and takes only 6 mm of rail space per protected pair, making it one of the most space-efficient DIN-rail SPDs available for 24 V DC instrument signal protection. This is critical in Saudi EPC panel designs where marshalling cabinet rail space is allocated to hundreds of instrument loops, each requiring individual SPD protection per IEC 61000-4-5 requirements and ARAMCO engineering standard GI-0476 (Surge Protection of Instrumentation and Control Equipment). The DEK 5 is thermally protected — in case of an overloaded MOV following multiple severe surge events, a thermal disconnect integrated into the varistor body opens the circuit, preventing sustained overvoltage damage and fire risk from a degraded MOV. A visual indicator flag confirms SPD functional status, enabling quick inspection during marshalling panel commissioning checks by ARAMCO instrument engineers.

Lightning-induced surges on instrument cable runs in Saudi Arabia are a significant concern due to the flat open-desert terrain of the Eastern Province and the extended cable runs between wellhead junction boxes and GOSPs — runs of 2–5 km are common in Ghawar and Khurais — which act as large loop antennas for electromagnetic field transients associated with lightning strikes. IEC 62305-4 (Protection of electrical and electronic systems within structures) recommends surge protection at both ends of cables entering or leaving a structure, and ARAMCO's GI-0476 specifically mandates SPD installation at instrument loop panel entry points for cable runs exceeding 30 m in open ground. The DEK 5 meets GI-0476 requirements as a Type 3 SPD for the panel-end interface, protecting PLC analog input modules and DCS I/O cards from lightning-induced common-mode and differential-mode transients.

Razz Middle East stocks the DEK 5 in 24 V DC and 110 V AC variants in Riyadh and Jeddah, and provides complete surge protection system design services for Saudi panel builders working to ARAMCO GI-0476 and IEC 62305-4 requirements. Services include: identification of cable runs requiring SPD protection, SPD type selection (Type 1, Type 2, or Type 3 per IEC 61643-21 classification), energy coordination between main panel entry SPD and instrument-loop SPD, and SPD monitoring relay design for DCS alarm integration. All DEK 5 devices are supplied with Weidmüller CE declarations, IEC 61643-21 test reports, and SASO customs clearance documentation.