DNU2 Surge Protection Device Installation
The DNU2 SPD mounts easily inside distribution or control panels. Snap it onto a 35 mm DIN rail and connect L/N conductors through the SPD terminals (with ground/PE to earth). Follow wiring diagrams and use recommended upstream fuses/breakers. The device should be installed upright (≤5° tilt) in a clean, low-vibration area; avoid corrosive, explosive, or dusty atmospheres. A dedicated supply breaker (gL/gG) must be installed ahead of the SPD for backup protection.
The Type 2 models (C100/C120) are ideal for general overvoltage/shunting protection on distribution circuits, while the Type 1 models (B15) handle direct lightning energy. In practice, use the DNU2 in factories, offices, or high-end homes for residential surge protection, and in factories or utility substations for industrial surge protection. Its versatility fits “plug-and-protect” on almost any low-voltage system needing a DIN-rail SPD.
DNU2 Surge Protection Device Applications
The GRL DNU2 series provides robust surge protection in demanding environments. Typical installations include:
- Telecommunications and Data Centers: Protecting communications equipment and servers from surges.
- Postal and Network Infrastructure: Safeguarding control systems in postal networks and logistics facilities.
- Railway and Transportation Systems: Ensuring reliable power protection for railway signaling and transit systems.
- Oil & Gas Installations: Providing surge defense in oilfields and related industrial sites.
- High-Rise Buildings: Securing electrical distribution in residential and commercial high-rise buildings.
In each of these applications, the DNU2 SPD remains inactive under normal conditions. When a surge occurs (from lightning strikes or switching events), it activates in nanoseconds to shunt excess voltage and current safely to earth. Once the surge subsides, the SPD automatically resets and returns to standby mode, ready for the next event.
Model Selection Guide
Choosing a DNU2 Surge Protection Device model depends on the required surge capacity and the type of system.
In the model name “DNU2-C100”: “C” indicates a Class II (Type 2) SPD, and “100” implies a 50 kA nominal discharge current (In). Similarly, “C120” denotes 60 kA In. The “B” series (e.g., B15, B25) is Class I (Type 1) SPD rated 15 kA or 25 kA. After this code, add the system voltage and pole configuration (for example, “385V 3P”, “550V 1P+N”); an optional “F” suffix indicates a plug-in (fast-replace) design. Example: DNU2-C100–385V–3P is a 50 kA Type 2 SPD for a 3-phase 385 V AC system. Refer to the ordering code list in the GRL catalog for exact part numbers.
In general, select a Type 2 (Class II) unit for most modern panels, or a combined Type 1+2 SPD when heavy lightning exposure is expected. For residential or light-commercial use, ensure the SPD’s In rating matches the local surge environment and that proper upstream fusing is provided.
