IN Brief:
- DEHN has extended its Advanced Circuit Interruption range into Type 1 applications with the DEHNventil ACI M TNS 264 FM.
- The device integrates switch and spark-gap protection into the SPD, removing the need for backup fuses while providing galvanic isolation, no leakage current in normal operation, and higher TOV resistance.
- For switchgear builders and installers, the product is aimed at feed-in side installations where short-circuit levels, cable length limits, and selectivity questions complicate conventional SPD protection.
DEHN has extended its ACI platform into the Type 1 segment with the launch of the DEHNventil ACI M TNS 264 FM, a modular combined arrester aimed at the supply point of low-voltage switchgear. The move broadens a technology family previously established in Type 2 applications and targets installations where higher short-circuit currents and tighter protection coordination make conventional SPD protection harder to engineer.
The product is built around DEHN’s Advanced Circuit Interruption approach, which replaces the usual external backup fuse arrangement with an integrated switch and spark-gap combination inside the surge protective device itself. In practice, that changes the planning equation for designers and installers by combining overcurrent protection with galvanic isolation in normal operation, eliminating leakage current, and improving resistance to temporary overvoltage at mains frequency.
The feed-in side is where those details matter most. Type 1 lightning current arresters need to be installed as close as possible to the feeding point, yet connection cable length is typically limited to 0.5 metres to control inductive voltage drop. DEHN says the integrated ACI design removes the need for arrester backup fuses, allows direct mounting on earthed DIN rails or earthing rails, and keeps 16 mm² copper conductors sufficient even under fault conditions because the integral current remains low enough to avoid thermal overloading of the connection cable.
The TNS version is a Type 1+2+3 device for 230/400 V TN(C)-S systems with a stated total lightning impulse current of 100 kA, a protection level of up to 1.5 kV, and an 11-module DIN width. The disconnection function also allows the module to be replaced during operation from the side or the front using insulated tools, which places maintainability alongside surge performance in the product’s design.
As renewable generation, automation, and networked loads continue to alter fault behaviour and protection requirements, devices that cut cabinet complexity and reduce selectivity calculations are likely to draw attention. Technical details for the DEHNventil ACI M TNS 264 FM are available here.
