high voltage disconnectors monitoring

The needs

An international company, leader in the production and sale of disconnection systems for high voltage electrical substation, expressed the need for a monitoring system specifically designed to ensure the correct operations and to optimize the preventive maintenance processes of their products. The system had to monitor some key parameters of the high voltage disconnector devices

  • Working temperature of the electrical contact points (knives, blades…) to evaluate the state of usury or oxidation
  • Absolute 3D position of the mechanical moving parts to evaluate their correct static placement during the normal operating states of the disconnector
  • Earth leakage current through insulators of the main structure to evaluate the state of usury and cleaning

These parameters are considered highly relevant for the correct behaviour of the devices and give an indication of their operational status and any maintenance need. The system had to support some components (temperatures and 3D position sensors) operating at monitored line HV potential (up to 420kVac or 1.1MVdc) and other components (earth leakage current sensors and control devices) operating at the ground potential.

In this configuration it was strictly necessary that the parts operating at HV potential were able to operate while immersed in strong electric and magnetic field, that they were independently powered by energy sources operating at the same HV potential, and that the digital communication between the single components took place in a completely wireless and secure way.The components operating at HV potential had to be powered by energy harvesting sources (magnetic or solar) and store energy to allow a long operating autonomy even in absence of the primary energy source.

All data collected by the monitoring system had to be made available to the HV substation control applications using standard interfaces, to allow the complete configuration management and the firmware update of all components. In addition to this native integration with the HV substation control applications, the system also had to be remotely managed via a dedicated WEB application using an additional cellular WAN connectivity module.

The system also had to allow the autonomous and programmable control of up to five dry contacts to activate local alarms/indications in stand-alone mode, without the need of connection with any external control system.

The challenges

  • Temperature detection from multiple points with wide measuring range (-50 / +200°C)
  • Measurement of inclination angles on the three axes with respect to the ground (3D absolute position)
  • Measurement and statistical indicators (RMS, Peak, StdDev..) of the insulator's leakage current
  • High immunity to strong electric and magnetic fields and to possible impulsive electric discharges
  • Bidirectional and secure radio communication of the HV potential components with the other ones
  • Ultra low-power design with support for magnetic and solar energy harvesting and for local energetic storage
  • Minimum dimensions, adaptable to the whole disconnector family required by the customer
  • Support of multiple sensors and lines (electrical phases) for each system
  • Integration with HV substation control systems
  • IP degree and UV protection for outdoor installations with a wide range of operating temperature
  • Dedicated WEB application for data view and historical KPIs analysis

The realization

The HVDM03 monitoring system for HV disconnectors is composed of different devices that realize, in a highly flexible and scalable way, the functionalities required by the customer.

A single HVDM03 system is designed for the complete monitoring of a three-phase HV disconnector and is made up of the following elements


  • Up to six HVDM03-S wireless sensors with BLE 5 connectivity, placed on the three phases of the HV disconnector (up to two HVDM03-S sensors for each phase) to detect up to three contact temperatures and the 3D position of the disconnector bars using an integrated MEMS sensor. Each device is autonomously powered by a harvesting circuit that captures energy from a solar panel or from a current transformer placed on the power conductor nearby the disconnector.
  • Up to three HVDM03-L wired current sensors (one for each phase) that measures various statistics related to the earth leakage current due to insulators pollution.
  • A basic HVDM03-B, installed on a DIN-rail inside the control panel, which communicates wirelessly with the HVDM03-S sensors and via a RS485 interface with the HVDM03-L sensors, and provides a RS485 ModbusRTU interface to interact with the HV substation control systems. This base module can also independently control up to five dry contacts (relays) for the logic signalling of configurable alarm or warning conditions.


A single HVDM03 system applied to a three-phases HV disconnectors can therefore detect temperature of up to 18 points (6 temperatures per electrical phase), the 3D positions of up to six moving parts (2 3D positions per electrical phase) and the earth leakage current value of up to 3 post insulators.

The HVMD03-B base module is the central point of the system and collects data from all the measurements devices associated with it. It makes them available on a standard RS485 ModbusRTU interface, with slave/server functionality, and on an integrated WEB interface accessible via a direct WiFi connection.

The control interfaces of the HVDM03 system also allow the firmware update of all its components and the complete configuration of working parameters in order to obtain the maximum flexibility of usage.

An optional HVDM-M device allows the remote management and monitoring of up to four different HVDM03 systems via a dedicated WEB application available as IaaS, PaaS e SaaS.

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