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Reliability meets automation.

Your benefits at
a glance

  • Proven drive function for tap changers
  • Reliable monitoring of transformers
  • Cost-saving operation, cost-efficient implementation
  • Easy to operate, intuitive graphics interface
  • Modular structure, individual expansion possible
  • Automatic voltage regulation


Capture, evaluate, store, and visualize transformer data and drive the on-load tap-changer. ETOS® ED. Integrated intelligence.

In addition to driving the tap-changer (using a mechanical drive shaft), ETOS® ED lets you evaluate and record all of the relevant operating data from your power transformer, such as monitoring the tap changer or evaluating transformer utilization. ETOS® ED helps with focused planning of operation and maintenance. The solid, proven housing protects both the motor-drive unit and the integrated monitoring system. ETOS® ED is also ideal for retrofitting monitoring functions on older transformers. Optional automation solutions such as voltage regulation and cooling system control can also be included in the ETOS® ED order and used as supplementary equipment for controlling the transformer.

Minimum wiring, maximum flexibility.

Fitting ETOS® ED on the transformer directly transfers all relevant data to the control station via network protocol using a fiber-optic cable. This greatly reduces the amount of wiring needed during installation and significantly cuts costs compared to a conventional connection method. Integration of additional functions makes this added value available to you without even impacting system costs. We are happy to advise you and develop solutions with you that are tailored to your exact needs. Of course, we can even commission your systems on site on request.


Open system. ETOS® functions.

Efficient control and monitoring of transformers.

  • Innovative top drive or proven drive technology with mechanical drive linkage
  • Integrated motor current monitoring and monitoring of tap position
  • Conforms to IEC 60214-1:2014
Standard functions (contained in every ETOS® design)
  • Status monitoring of the protective devices (e.g. RS2001, Buchholz relay, PRD)
  • Monitoring the oil temperature
  • System voltage, load current, frequency, load factor, active power, reactive power, apparent power
  • Hot-spot calculation in accordance with IEC 60076-7 or ANSI/IEEE C57.91
  • Calculation of aging rate and loss-of-life
  • Tap position capture
Advanced functions
  • Capability of transformer to handle overload in the short or long term with live calculation and simulation of overload forecasts in accordance with IEC 60076-7 or ANSI/IEEE C57.91
  • Calculation of the bubbling temperature
  • Calculation of paper moisture content
Cooling system monitoring
  • Number of starts per cooling level
  • Operating time per cooling level
  • Monitoring of Rth and cooling efficiency
Cooling system control
  • Switching points, hysteresis and delay times adjustable to your needs
  • Various control algorithms (Periodic cooling group activation or predictive cooling)
  • Fail-safe mode
  • Optional as frequency-controlled cooling system control for increased performance and lower fan wear
Standard functions
  • Status monitoring of the motor-drive signals
  • Maintenance recommendations and maintenance interval calculation for OILTAP® and VACUTAP®
  • Calculation of contact wear for OILTAP®
  • Tap-position statistics for the OLTC (number of tap-change operations/tap, duration per tap)
  • Monitoring of OLTC oil temperature
Advanced functions
  • Motor current index in accordance with IEEE PC57.143
  • For ETOS® ED: OLTC torque monitoring
  • Online recording of up to ten corrosive gases, relative moisture in oil and relative overall gas content
  • Configurable limit value for each gas
  • Diagram of the measured values
  • Measured value memory
  • Universal 4…20mA or Modbus RTU Interface for capturing the DGA sensor signals
  • Standard evaluation methods in accordance with Duval, Rogers, Dörnenburg and IEC 60599
Standard functions
  • Measurement of system voltage and load current (single- or three-phase)
  • One desired value
  • Voltage regulation with linear delay time T1
  • Status of the motor-drive unit
Advanced functions
  • Various types of desired-value setting (three or fi ve desired values, TAPCON® Dynamic Setpoint Control, desired-value setting via analog value, raise/lower pulse, desired value via BCD)
  • Automatic voltage regulation with linear or integral time characteristics and two delay times T1 and T2
  • Parallel operation via CAN bus (up to 16 transformers)
  • Line drop compensation (RX or Z compensation)
  • Monitoring of bandwidth
  • Function monitoring
  • Limit-value monitoring
  • Monitoring of changes in C1 capacitance
  • Monitoring of the dissipation factor (tan δ)
  • System voltage
Additional functions
  • Freely programmable digital and analog inputs and outputs
  • Open programming with function blocks possible with TPLE function
  • Optional: Integration of functions in a motor-drive unit for the on-load tap-changer (side drive or innovative top drive)
  • Optional: Integration of the complete control including power unit of a conventional cooling system. Can also be combined with the advantages of intelligent cooling system control, such as predictive cooling (on request)
  • Visualization using web server (SVG and HTML 5) included as standard for various end devices
  • IEC61850 Ed. 1 and Ed 2. MMS, and GOOSE
  • IEC60870-5-101, -103, -104
  • DNP3
  • Modbus TCP, RTU, ASCII
  • Remote maintenance support