DEHNguard® modular

Modular Surge Arrester with integrated Backup Fuse

Arrester backup fuse integrated in the protection module Prewired complete unit consisting of a base part and plug-in protection modules Energy coordination with other arresters of the Red/Line product family High discharge capacity High reliability due to "Thermo Dynamic Control" SPD monitoring device Easy replacement of protection modules without tools due to module locking system with module release button


DEHNguard M TT CI 275: With integrated backup fuse for TT and TN-S systems ("3+1" circuits)

DEHNguard M TN CI 275: With integrated backup fuse for 230 V TN systems

DEHNguard M TT 2P CI 275: With integrated backup fuse for 230 V TT and TN systems ("1+1" circuits)

DEHNguard S CI 275: Modular single-pole surge arrester with integrated backup fuse

DEHNguard M ... CI 275 FM: With remote signalling contact for monitoring device (floating changeover contact)


Featuring the functional Red/Line design, the modular surge arresters of the DEHNguard ... CI family combine short-circuit and surge protection in a single protection module, setting new patterns for ease of application. The protective circuit including the arrester backup fuse in the protection module and the heavy-duty zinc oxide varistor as well as the dual Thermo Dynamic Control monitoring device allow easy installation with minimum space requirements. With the already integrated arrester backup fuse, the user no longer has to care about arrester-specific dimensioning requirements such as backup protection in the event of a short-circuit and impulse current carrying capability.

Space-saving surge protection measures covering all functions specified in the installation standards can be implemented in installations with short-circuit currents up to 25 kArms. All paths including the N-PE path feature an operating state indicator as required by the IEC 60364-5-53 standard. Due to the "Thermo Dynamic Control" monitoring device, the surface temperature of the heavy-duty varistor and the intensity of the discharge current are used for evaluation. The state of each protective path is shown by means of a red and green mechanical indicator which needs no power to operate. It also indicates the activation of the "Thermo Dynamic Control" monitoring device and the integrated arrester backup fuse. In addition to this mechanical operating state / fault indication, the ... FM version of the DEHNguard ... CI devices features a three-pole remote signalling terminal. With its floating changeover contact, the remote signal can be used as break or make contact according to the particular circuit concept.

All the benefits of the modular design of the DEHNguard family have been integrated into the new DEHNguard ... CI family. The system-configuration-specific product designation and the "Thermo Dynamic Control" monitoring device reflect the high safety requirements. The unique module locking system prevents the protection modules from becoming loose due to shock during transport or the enormous forces of discharge. Nevertheless, the protection modules can be easily replaced without tools, the need to de-energise and removing the distribution board cover by simply pressing the easy-to use module release button of the protection modules. Each protective circuit of the multipole and single-pole arresters and each protection module is mechanically coded to ensure against installing an incorrect protection module.

The surge arresters of the mutlipole modular DEHNguard ... CI family feature multifunctional terminals on a standardised spacing of one module for connecting conductors and busbars, allowing easy wiring with other DIN rail mounted devices. Thus, a variety of applications can be easily connected in series in accordance with IEC 60364-5-53 for optimal protection.


Type DG M TNC CI 275 DG M TNC CI 275 FM
Part No. 952 304 952 309
SPD according to EN 61643-11 / IEC 61643-11 type 2 / class II type 2 / class II
Nominal a.c. voltage (UN) 230 / 400 V (50 / 60 Hz) 230 / 400 V (50 / 60 Hz)
Max. continuous operating a.c. voltage (UC) 275 V (50 / 60 Hz) 275 V (50 / 60 Hz)
Nominal discharge current (8/20 µs) (In) 12.5 kA 12.5 kA
Max. discharge current (8/20 µs) (Imax) 25 kA 25 kA
Voltage protection level (UP) ≤ 1.5 kV ≤ 1.5 kV
Voltage protection level at 5 kA (UP) ≤ 1 kV ≤ 1 kV
Response time (tA) ≤ 25 ns ≤ 25 ns
Max. mains-side overcurrent protection not required not required
Rated breaking capacity of the internal backup protection 25 kA 25 kA
Short-circuit withstand capability (ISCCR) 25 kArms 25 kArms
Temporary overvoltage (TOV) (UT) – Characteristic 335 V / 5 sec. – withstand 335 V / 5 sec. – withstand
Temporary overvoltage (TOV) (UT) – Characteristic 440 V / 120 min. – safe failure 440 V / 120 min. – safe failure
Operating temperature range (TU) -40 °C ... +80 °C -40 °C ... +80 °C
Operating state / fault indication green / red green / red
Number of ports 1 1
Cross-sectional area (min.) 1.5 mm2 solid / flexible 1.5 mm2 solid / flexible
Cross-sectional area (max.) 35 mm2 stranded / 25 mm2 flexible 35 mm2 stranded / 25 mm2 flexible
For mounting on 35 mm DIN rails acc. to EN 60715 35 mm DIN rails acc. to EN 60715
Enclosure material thermoplastic, red, UL 94 V-0 thermoplastic, red, UL 94 V-0
Place of installation indoor installation indoor installation
Degree of protection IP 20 IP 20
Capacity 3  module(s), DIN 43880 3  module(s), DIN 43880
Type of remote signalling contact changeover contact
a.c. switching capacity 250 V / 0.5 A
d.c. switching capacity 250 V / 0.1 A; 125 V / 0.2 A; 75 V / 0.5 A
Cross-sectional area for remote signalling terminals max. 1.5 mm2 solid / flexible
Weight 376 g 382 g
GTIN 4.01E+12 4.01E+12
PU 1 pc(s) 1 pc(s)
Product Specifications (PDF) Product Specifications (PDF)