Two-winding transformer differential protection with automatic voltage regulator
Two-winding transformer differential protection with automatic voltage regulator
Two-winding transformer differential protection with automatic voltage regulator
Two-winding transformer differential protection with automatic voltage regulator
The E3-TR is a dedicated two-winding transformer protection and control IED with an integrated automatic voltage regulator; the relay provides complex protection, control and monitoring functions for two-winding power transformers. The E3-TR device also provides an integrated tap changer controller for voltage regulation of power transformers with motor-driven OLTC (on-load tap changer). The device is member of the DTRV product type in the EuroProt+ product family.
The DTRV type is especially designed for protection and control applications for power transformers and generators including power generator-transformer blocks. Additionally, the DTRV product type includes a variety of versatile protection functions to meet user requirements.
A voltage regulator can be integrated in the same device together with the protection functions or as a stand-alone IED. The voltage adjustment function can be performed automatically or, in manual mode of operation, the personnel of the substation can set the network voltage according to special requirements. The intelligent voltage control function can handle up to 4 parallel transformers depending on the minimum circulating current or master-slave principles.
Because of the control, measuring and monitoring functions implemented, the IED can also be used as a bay control unit.
The EuroCAP configuration tool, which is available free of charge, offers a user-friendly and flexible application for protection, control and measurement functions to ensure that the IED-EP+ devices are fully customisable.
The E3-TR is a dedicated two-winding transformer protection and control IED, the relay is aligned for complex protection, control and monitoring functions of two-winding power transformers. The device also features an integrated voltage regulator. It is member of the DTRV product type in the EuroProt+ product family.
The E3-TR relay provides a variety of versatile protection functions along with the main transformer differential protection, such as 3ph, Io and I2 overcurrent protection, overload protection, restricted earth-fault protection etc.
Sensitive restricted earth-fault protection (REF) is the final element in the overall differential protection system, which detects even single phase-to-ground faults close to the grounded neutral of the transformer.
The multiple instances of the implemented three-phase and residual overcurrent functions are provided for the segregated protection of both transformer windings. Furthermore, several voltage-based protection functions are available for the voltage controlled side of the transformer based on the three phase-voltage measurement. It can be used as a back-up protection relay for downstream equipment (e.g. feeders, cables).
The E3-TR transformer protection relay can support double-breaker terminals on any side of the transformer such as breaker and a half or ring bus topology.
Automatic phase shift and turns ratio compensation for all types of transformer winding connections.
The IED includes a wide range of control and supervise functions, which provide full control and user-defined interlocking schemes for the primary switchgear at the substation.
The E3-TR configuration measures three phase currents, the residual current component from both sides of a two-winding, three-phase transformer and, additionally, three phase voltages. These measurements allow, in addition to the current- and voltage-based functions, directionality extension of the residual overcurrent function.
Voltage control is integrated in the same device together with the main transformer differential protection and restricted earth-fault protection functions.
The additional protection functions can provide back-up protection for downstream equipment (e.g. feeders, cables).

| Protection & control functions | IEC | ANSI | *Inst. | |||
|---|---|---|---|---|---|---|
| Differential Protection Function (versions 5 and up on 2.10 systems) | 3IdT > | 87T | 1 | 2024.12.18. | download | |
| Overexcitation protection function | V/Hz | 24 | 1 | 2024.12.20. | download | |
| Definite time undervoltage protection function | U<, U<< | 27 | 2 | 2024.12.19. | download | |
| Negative sequence overcurrent protection function | I2> | 46 | 1 | 2025.04.04. | download | |
| Negative sequence definite time overvoltage protection function | U2 > | 47 | 1 | 2024.10.10. | download | |
| Line thermal protection function | T > | 49 | 1 | 2025.01.03. | download | |
| Three-phase instantaneous overcurrent protection function | I >>> | 50 | 2 | 2025.01.17. | download | |
| Residual instantaneous overcurrent protection function | Io>>> | 50N/50G | 2 | 2025.12.09. | download | |
| Breaker failure protection functions | CBFP | 50BF | 2 | 2022.10.03. | download | |
| Three-phase time overcurrent protection function | I>, I>> | 51 | 2 | 2025.04.04. | download | |
| Residual overcurrent protection function | Io>, Io>> | 51N/51G | 2 | 2025.04.04. | download | |
| Definite time overvoltage protection function | U>, U>> | 59 | 2 | 2024.12.19. | download | |
| Residual definite time overvoltage protection function | Uo>, Uo>> | 59N | 2 | 2024.12.20. | download | |
| Current unbalance function (CT Supervision) | 60 | 2 | 2024.12.20. | download | ||
| Directional residual time overcurrent protection function | Io Dir>, Io Dir>> | 67N/67G | 2 | 2025.12.03. | download | |
| Overfrequency protection function | f>, f>> | 81O | 2 | 2024.12.20. | download | |
| Underfrequency protection function | f<, f<< | 81U | 2 | 2024.12.20. | download | |
| Rate of change of frequency function | df/dt | 81R | 2 | 2024.12.20. | download | |
| Restricted earth-fault protection function | REF | 87N | 2 | 2024.12.10. | download | |
| Automatic tap changer controller function (parallel transformers included) | 90V | 1 | 2023.01.13. | download |
| IEC61850 documents | |||
|---|---|---|---|
| TISSUEs Implementation Conformance Statement (TICS) for the IEC 61850 Edition 2 server interface in Europrot+ product family | 18/04/2023 | download | |
| Protocol Implementation eXtra Information for Testing (PIXIT) for the IEC 61850 Edition 2 server interface in Europrot+ product family | 18/04/2023 | download | |
| Protocol Implementation Conformance Statement (PICS) for the IEC 61850 Edition 2 server interface in Europrot+ product family | 18/04/2023 | download | |
| Model Implementation Conformance Statement (MICS) for the IEC 61850 Edition 2 server interface in DTRV product | 18/04/2023 | download | |
| Protocol Implementation eXtra Information for Testing (PIXIT) for the IEC 61850 Edition 1 server interface in Europrot+ product family | 20/03/2017 | download | |
| Protocol Implementation Conformance Statement (PICS) for the IEC 61850 Edition 1 server interface in Eurorot+ product family | 20/03/2017 | download | |
| Model Implementation Conformance Statement (MICS) for the IEC 61850 Edition 1 server interface in the Eurorot+ product family | 21/05/2012 | download | |
| Type description | |||
| Transformer protection & control | 18/07/2025 | download | |
| Hardware Guides | |||
| Hardware description | 05/05/2025 | download | |
| Maintenance guide | 28/06/2023 | download | |
| Application Guides | |||
| Operating Manual and Troubleshooting Guide - system version: 2.8 | 19/09/2023 | download | |
| Configuration Descriptions | |||
| E3-TR configuration description | 23/05/2014 | download | |
| E3-TR_H product configuration options | 05/01/2026 | download | |
| E3-TR_F product configuration options | 05/01/2026 | download |
| E3-TR_H: | ![]() |
E3-TR_F: | ![]() |