Accessories for smart transformers - eDevices

Liquid level indicators for smart transformers

Liquids like mineral and silicone oils insulate and cool a transformer. You need to monitor the level of the oil to assure reliable and safe operation of the transformer.

Choose our liquid level indicator type eOLI, an evolution of our conventional liquid level indicators, and continuously monitor from the remote any unexpected or accidental oil leakages that may lead to a transformer failure. The operator can monitor the preset values remotely or visualize the values on-site at men-height through the easy-to-read eViewer dial installed on the transformer wall and decide on the best transformer maintenance schedule.

The indicator 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

  • Continuous online monitoring at any time and from the remote
  • Proven technology enabling the end-user informed decision making about effective transformer maintenance schedule
  • Customizable mounting flange suitable for all transformer designs
  • Adjustable value settings for alarms and switches
  • Compatibility with other eDevices, and third-party accessories enables the end-user a controlled and gradual digitalization of the transformer and remote asset health monitoring
  • Easy installation
  • Maintenance free


  • Smart grid applications
  • Liquid-filled transformers with or without conservator
  • Conservator with rubber bag
  • Suitable for new installations and retrofits
  • Suitable for offshore environment
  • Suitable for tropical climates
  • Part of our MeDICA solution

Additional accessories

  • eViewer enabling accurate liquid level reading at men-height on-site

Technical data at a glance

HousingAluminum alloy
InstallationIndoor, outdoor and Tropical proof
LensPlycarbonate or tempered glass
FlangeAluminum alloy
Flange designeOLI22
COMEM design, 8 holes
Compatible with all transformer designs
DialNumbers and letters directly printed on the aluminum plate
Customizable range (MIN +20°C MAX, other available)
Red needle
Adjustable switchesYes
Ventilation valveYes
Float elementExpanded ebonite
Float movementRadial, axial, axial for rubber bag
Oil temperatureFrom -40°C up to +120°C
Ambient temperatureFrom -40°C to +80°C
Cable gland3; M25x1.5
Degree of protectionIP66
Power supply24 V dc ±10% polarized
Analog output4-20mA
Digital outputModbus RTU
Data logger
eViewer – additional dial
at men height
Enables liquid level value check on site; Power supply 24 V dc

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