Accessories for smart transformers - eDevices

Self-dehydrating breathers

Moisture is a leading cause of transformer aging and outages. By choosing our condition-based self-dehydrating breather type eSDB for your transformer, you do not need to worry about site inspections and silica gel replacement. Your transformer will be continuously secured from moisture intake and you can collect data online required for your transformer health management remotely.

The breather is equipped with a digital interface for easy connection to smart grid applications and can be integrated into a system through a central control unit.

It is compatible with our complete eDevice family, can be connected also to third-party devices, and be part of our modular monitoring ecosystem for transformer diagnostics – MeDICA.

Contact us and get support with the product selection.

Why buy:

Transformer safety:

  • Proven technology assures safe transformer operation
  • Integrated innovative features facilitate the device management and enable remote control
  • The presence of a double tank in all models guarantees uninterrupted continuous automatic silica gel regeneration
  • Condition-based regeneration cycle secures longer lifetime and good dehydrating performance of the breather


  • Robust and compact design with no external wires for easy installation and maintenance
  • If the silica gel in the breather is contaminated with oil leakage during the transformer installation, the salt is easily replaceable on site
  • USB-A data logger and added connectivity features enable full control over the data collection from the device and make firmware upgrade easy for the user, additional cable or notebook not needed

Remote monitoring and control:

  • Possibility to remote the control signals through common communications protocols
  • Temperature, humidity, and silica gel status continuously monitoring


  • With only 4 models, we cover the full range of applications (see in the selection matrix below)
  • Suitable for new installations and retrofits
  • Data monitoring available through Modbus and 4-20 mA
  • Compatible with EN and DIN standards
  • Part of our MeDICA solution

Technical data at a glance

MaterialAll the external parts are resistant to transformer oils, salt fog, and UV rays – Treated aluminum and stainless steel
Types of installation environmentIndoorCorrosion class: C5-MediumGrey coating
OutdoorCorrosion class: C5-MediumGrey coating
Coastal areaCorrosion class: C5-MediumGrey coating
Off shoreCorrosion class: CXRAL 7035
Ambient temperatureFrom -40 °C to +80 °C
Degree of protectionIP55 according to EN60529;
IP65 according to EN60529 for terminal box
DessicantColorless, non-poisonous silicagel; amount according to model
Ventilation valveTo prevent the formation of condensation
Cable glands2 M25x1.5
Functional testStandard
Rated voltage – Power SupplyFrom 5 to 230 V ac/dc ± 10% 50/60 Hz
Overvoltage protectionStandard (replaceable varistor and fuse)
Heating element protectionStandard (replaceable fuse)
RedundancyFor eSDB type M, L: Double feedback signal – Load cell and Humidity sensor
DisplayUser-friendly – Quick access menu
Current consumptionIn-rush current < 10 A – Maximum current during regeneration < 3 A
Recommended wiresPower supply: 14 AWG
Relays: 18 AWG
Analog outputs: 2 x 18 AWG (shielded twisted cable)
Digital outputs:
– Modbus RTU – 2 x 18 AWG shielded twisted cable
– Modbus TCP/IP – Category 5e straight cable
Analog output2 x 4-20 mA
Digital outputMODBUS RTU – Modbus TCP/IP – Datalogger
Flange typeDIN & EN flange

(1) For critical environmental conditions, please contact us(

Selection matrix

Arc suppression coil (Peterson coil)X
Air-filled cable boxesX
Traction transformersX
Phase-shifting transformers ≤60 MVAX
Shunt reactors < 60 MVAX
Network ≥60 MVA ≤200 MVAX
Phase-shifting transformers ≥60 MVA ≤200 MVAX
Shunt reactors >60 MVA ≤200 MVAX
Step-up transformers ≥60 MVA ≤200 MVAX
Generator and network >200 MVAX
Phase-shifting >200 MVAX
Shunt reactors >200 MVAX
HVDC transformersX
Furnace transformersX
Cavern transformersX
Quantity of oil≤ 40t≤ 40t40 ≤ 80t≥ 100t