Special application transformers
Designing transformers for special applications requires both experience and expertise. Equipped with both, we design and manufacture transformers that fit your operation, whatever the application.
Do you need help with earth-fault compensation, reactive power, converter operation, motor start, railway or any other special application? We will help you find the right solution.
What do you need help with?
Compensate earth-fault currents or reactive power
Solutions for earthing, Petersen coil and reactive power compensation.
Solutions for rectifiers, furnace, motor start or railway
Transformers for demanding applications and specific operating conditions.
Verify capacity, standards and technology level
View technical specifications, standards and what we can deliver.
Describe your application and get help choosing the right unit
Contact us and we will help you put together the right solution.
Guidance — which solution fits your need?
| Need | Recommended solution |
| Compensate earth fault currents | Earthing transformer / BTB Treactor |
| Compensate reactive power | Shunt reactor |
| Combine earth fault and reactive power compensation | Shunt reactor with Petersen coil function |
| Handle harmonics from rectifiers or frequency converters | Rectifier and converter duty transformer |
| Limit motor starting currents | Starting transformer |
| Handle extreme currents | Furnace transformer or rectifier transformer |
| Adaptation for railway systems | Railway transformer / booster transformer |
Compensating equipment
If you need equipment to compensate earth-fault currents, reactive power or a combination of both, we offer standard and bespoke solutions for both centralised and distributed compensation.
Centralised compensation
Earthing transformer (with Petersen coil)
An earthing transformer with a built-in Petersen coil compensates earth faults. The Petersen coil can have a fixed compensation value or be equipped with a tap-changer with fixed steps for adjusting the compensation value.
This product is typically used in addition to an existing adjustable Petersen coil at a power transformer substation when the need for compensation grows and the existing Petersen coil becomes too small.
Shunt reactor (with Petersen coil function)
Shunt reactors are used to compensate capacitive reactive power generated by long, lightly loaded distribution lines and underground cables. Shunt reactors can also be designed to function as a combined shunt reactor with Petersen coil functionality.
For shunt reactors, thoughtful electrical design and a robust mechanical construction are critical. This combination reduces vibrations in the structure and therefore also the noise level.
Specifications:
- oil-immersed shunt reactor up to 145 kV and 63 kVA
- fixed compensation value or adjustment via a manual or motorised tap-changer
- variable shunt reactor (VSR) with tap-changer
- with or without Petersen coil functionality
- in accordance with the reference standard IEC 60076-6
Distributed compensation
Distributed compensation complements centralised compensation and is particularly well suited to large underground cable networks.
BTB Treactor
Transformer with earthing transformer functionality and a built-in Petersen coil for distributed earth-fault compensation.
24 kV series:
- oil-immersed distribution transformer: 50–1000 kVA, 20,500 V ±2×2.5 % / 400 V
- earthing transformer with a maximum neutral current of 15 A as standard
- Petersen coil with fixed steps: 0-5-7.5-10-12.5-15 A
Shunt reactor with Petersen coil function
Combined solution for distributed compensation of both reactive power and earth-fault currents.
24 kV series:
- 20.5 kV oil-immersed shunt reactor
- compensation power in fixed steps: 59-89-118-148-178 kVAr
- earth-fault compensation in fixed steps: 5-7.5-10-12.5-15 A
- can be integrated with a distribution transformer in the same tank
Other special application transformers
Earthing transformer & reactor
Creates an artificial neutral point in a three-phase system and enables earthing of the neutral with, for example, a Petersen coil or a neutral resistor.
Multi-voltage transformer
Designed to operate at various grid voltages with a fixed secondary voltage and reinforced for transport and operation in demanding environments.
Rectifier and frequency converter duty transformer
Specifically designed to handle current harmonics with phase-shifted secondary windings for 12-, 18- or 24-pulse operation.
Starting transformer
Used as a current limiter to start three-phase induction motors and reduce short-duration voltage dips in the grid.
Furnace transformer
Designed for severe operating conditions with recurring overloads, high current and low voltage.
Railway transformer
Designed and manufactured for specific railway systems, both AC and DC.
Booster transformer
Developed for the Finnish railway system at 25 kV AC 50 Hz, but can be adapted to other markets to customer requirements.
Capacity and design capability
- Special solutions for both centralised and distributed compensation
- Designs for complex applications in industry, energy and railway
- Various cooling principles, tap-changers and mechanical solutions depending on operating conditions
- Solutions tailored to both standard requirements and customer-specific technical parameters
Contact us
Let us plan your transformer solution
Tell us your requirements or describe your application and our experts will help you put together the right special transformer for your operation.