DehnDG-MOD-275Type 2 Varistor Surge Protection Module, 275 V AC, In 20 kA / Imax 40 kA, Plug-In Module for DEHNguard Base

Product Description

What this part is

A DEHN DG MOD 275 — the pluggable varistor protection module used in the DEHNguard modular surge arrester system. It is the sacrificial element: the base part stays wired into the distribution board and the module plugs into it, so a module that has reached end of life is swapped in seconds without breaking any connections. Classified as a Type 2 surge protective device to EN 61643-11, for main and sub-distribution boards.

Decoding the designation

DG – DEHNguard family, Type 2 varistor-based surge protection for power supply systemsMOD – protection module only, not a complete arrester275 – maximum continuous operating voltage Uc, 275 V AC952010 – DEHN part number

What these specs mean in practice

Two figures drive the selection. Uc 275 V AC is the continuous voltage the varistor tolerates indefinitely; on a 230/400 V TN system that gives headroom above nominal for supply variation, and it is the number to match — fitting a lower-Uc module on the same system shortens its life, fitting a higher one raises the let-through voltage. The discharge figures are a pair, not alternatives: 20 kA is the nominal discharge current In, the level the module is rated to survive repeatedly with an 8/20 µs wave, while 40 kA is Imax, a single-shot maximum. Design to In, not Imax. As a Type 2 device this belongs downstream of any Type 1 lightning current arrester at the service entrance, not instead of it.

Published specifications

Type: Type 2 surge protective device (SPD) per EN 61643-11, varistor basedMaximum continuous operating voltage Uc: 275 V ACNominal discharge current In: 20 kAMaximum discharge current Imax: 40 kAConstruction: pluggable protection module for DEHNguard modular base partsApplication: main and sub-distribution boards in low-voltage installations

Quantity and configuration

Sold as 1 piece — the protection module only. There is no base part, no DIN-rail mounting foot and no terminals in this item; it cannot be installed on its own. It is intended either as a replacement for a spent module in an existing DEHNguard M or S installation, or to populate a base part you already have. Complete arresters carry different part numbers — for example DG S 275 (952070) or the DG M TT variants — and include the base.

Installation and setup notes

Check the base part accepts this module and that the base’s pole configuration matches the system earthing arrangement before ordering — TN-S, TN-C and TT installations use different base parts even where the module is the same. The DEHNguard design includes a thermal disconnector and a mechanical status indicator; a module showing red has operated and must be replaced, and a red indicator is not a fault in the base. Where remote signalling is required, that comes from an FM-suffixed base part with a floating changeover contact, not from the module. Isolate the circuit before pulling a module, and always fit the arrester downstream of appropriate overcurrent protection as shown in the DEHN application data.

Interchange guidance

Modules are Uc-specific and not interchangeable across voltages: DG MOD 275 is a 275 V AC module and will not correctly protect — or survive on — a system that calls for a different Uc. Do not confuse this module with a complete arrester: DG S 275, DG S 275 FM, DG M TT 275 and DG M TT 2P 275 are assembled devices with base parts and their own part numbers. DEHNgap modules are spark-gap rather than varistor devices, with different let-through behaviour, and share only the mechanical format. Always quote the base part number as well as the module when ordering a replacement.