Purchase now: Weidmüller VPU AC II 3+1 300/50 Surge Protection
Purchase now: Atlantech Drives provides you the Weidmüller 2796790000 (Model: VPU AC II 3+1 300/50), a high-performance **Type 2 Surge Protection Device (SPD)** designed for low-voltage power distribution systems. This unit is configured for **3-Phase + Neutral** networks (TT and TN-S earthing systems). It protects sensitive electronic equipment (PLCs, drives, computers) from transient overvoltages caused by indirect lightning strikes or switching operations on the grid.
Technical Specifications and MOV Technology
The VPU AC II series utilizes advanced **Metal Oxide Varistor (MOV)** and **Gas Discharge Tube (GDT)** technology. The «300/50» rating indicates a maximum continuous operating voltage (Uc) of **300 V** and a discharge current (Imax) of **50 kA** per pole. The module features a visual status indicator (Green = OK, Red = Replace) and a remote signaling contact (telecom contact) to alert the BMS or PLC if a cartridge has blown.
- Part Number: 2796790000.
- Model: VPU AC II 3+1 300/50.
- Type: Type 2 / Class II.
- Network: 3-Phase + N (TT / TN-S).
- Max Voltage (Uc): 300 V AC.
- Discharge Current (In): 20 kA.
- Max Discharge (Imax): 50 kA (8/20 µs).
- Protection Level (Up): < 1.5 kV.
- Mounting: DIN Rail 35mm.
- Feature: Pluggable cartridges.
Expert Installation Advice: Cable Length Rule
SPDs are useless if installed incorrectly. Expert Tip: To maintain the protection level (Up < 1.5kV), the total cable length from the live busbar to the SPD and from the SPD to the earth bar must be less than **0.5 meters** (50 cm). If the cables are longer, the inductance of the wire adds voltage drop during a surge (V = L * di/dt), rendering the protection ineffective. Use V-wiring (Kelvin connection) if possible to eliminate the stub length.
Frequently Asked Questions (FAQs)
Q: Can I replace just the cartridge?
A: Yes, the VPU series features **pluggable cartridges**. If the indicator turns red, you can pull out the damaged module and insert a new one without rewiring the base.
Q: Do I need a fuse before it?
A: It depends on your main breaker size. The VPU AC II is self-protected up to 315 A gG. If your main fuse is larger, you must install a backup fuse (e.g., 125 A gG) in series with the SPD.
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