Three-phase transformer
Our variety of three-phase transformers / three-phase transformers offer many advantages:
- Use in three-phase systems to achieve the required voltages
- Adaptation and flexibility to specific customer requirements and broad portfolio
- Automation for welding three-phase transformers
- High quality, long usability and robust power supply made in Germany
- UL approval for a wide range of three-phase transformers
Examples of our three-phase transformers
Type series DTA/DTBA
Type series DTU / DTUL 0.15 to DTU / DTUL 30.0 according to VDE 0570 / EN 61558 Part 2 – 1 and UL 506 in spar winding according to VDE 0570 / EN 61558 Part 2 – 13 with index -A
- Three-legged core transformer / 3 UJ sheet cut
- Power range 200 – 30000 VA
- Frequency 50 / 60 Hz
- Insulation class T40 / B
- Protection class IP 00
- Suitable for installation up to IP 20, protection class I
- Vacuum soaked
- Foot angle fastening
- Connection to terminals
- From DTU / DTUL 1.0 with duct installation position
- vertical, in case of different installation
- approx. 10 performance reductions
- Contact protection according to VBG 4
Standard circuits
- Separate winding transformer star-star circuit with secondary zero point (Yyn0)
- Ballast-Spartransformer Star-Saving Circuit
- with zero point (Yna0). Recognizable
- end -A (e.g. DTU0, 12-A)
Type series DTB/DTBL
DTB / DTBL series (R 1.0 to R 30.0)
in accordance with VDE 0570 / EN 61558 Part 2 – 1 core transformer / 3 UJ laminated section
- Power range 2.0 – 30.0 kVA
- Frequency 50 / 60 Hz
- Insulation class T 40 / B
- Protection class IP 00, installation suitability up to IP 20, protection class I
- Vacuum soaked
- Terminals
- Foot angle fastening
- Contact protection according to VBG 4
- With air duct, installation position persecuting, approx. 10 reduction in performance when mounted horizontally
Standard circuits
- Separate winding transformer star circuit with secondary zero point (Yyn0)
- Series autotransformer Star autotransformer
with zero point brought out (YN
Type series DT/DTUL
Type series DT / DTL (R 15 to R 0.75) according to VDE 0570 / EN 61558 Part 2 – 1
- Three-legged core transformer / 3 UJ sheet cut
- Power range 25 – 1500 VA
- Frequency 50 / 60 Hz
- Insulation class T40 / B
- Protection class IP 00
- Suitable for installation up to IP 20, protection class I
- Vacuum soaked
- Foot angle fastening
- connection up to DT 120 to terminals, soldering eyelets or
- Solder swords, from DT 150 on clamps
- Contact protection according to VBG 4
Standard circuits
- Separate winding transformer star-star
- Circuit with secondary led out
- Zero Point (Yyn0)
- Ballast-Spartransformer Star-Saving Circuit
- with zero point (YNa0)
Three-phase transformers Definition
Three-phase transformers, also known as 3-phase transformers, play a crucial role in the efficient transmission of electrical energy. These industrial transformers are designed to meet the challenges of different mains voltages and types. Thanks to their additional taps as standard, they guarantee constant functional reliability and serve as the cornerstone for a reliable three-phase power supply.
Three-phase transformers Function
A three-phase transformer consists of a high-quality, laminated silicon steel core and three separately wound primary and secondary coils. The primary winding, also known as the three-phase primary coil, picks up the three-phase alternating voltage and generates an alternating magnetic field. This three-phase transformer ensures an even distribution of loads and a stable output voltage in all phases. In industrial applications, such as the metalworking or chemical industry, they are indispensable components for three-phase energy conversion.
Three-phase transformers Structure
The structure of a three-phase transformer is based on three identical coil systems arranged on a common iron core. These three systems correspond to the three phases of a three-phase network: L1, L2 and L3. Each of the three magnetically coupled legs has a primary and a secondary winding, which are electromagnetically connected to each other. This enables efficient voltage conversion with a compact design.
Winding arrangement
The windings of the three phases can be connected in different ways. The two most common types of connection are
Star connection (Y-connection): The winding ends are connected at a common point (star point). This circuit is particularly suitable for high-voltage applications.
Delta circuit (Δ circuit): The windings are connected together in a ring. This configuration is robust against unbalanced loads and is often used in industrial systems.
Combinations and switching groups
Depending on the grid requirements, the primary and secondary sides are connected in different combinations:
Yy0: Star-star circuit with the same phase position.
Dyn5: Primary side in delta, secondary side in star with 150° phase shift.
Yd11: Star-delta circuit with 330° phase shift.
The choice of switching group influences both the voltage transmission and the response to mains feedback, short circuits and harmonics.
Areas of application for three-phase transformers
Three-phase transformers are an indispensable part of modern energy infrastructures. Their main task is the low-loss conversion of electrical voltages in three-phase alternating current systems – both for energy transmission over long distances and for voltage adjustment in industrial and supply networks.
Typical areas of application:
Energy supply companies (EVU): In substations and distribution grids for the transformation of high voltage into medium and low voltage.
Industrial systems: For supplying large electrical consumers such as motors, machines and production systems.
Railroad technology and infrastructure: In traction systems and traction current networks.
Renewable energies: In wind farms and photovoltaic systems for feeding into the public grid.
Building technology: In large office complexes, hospitals or data centers to ensure a stable power supply.
Switchgear construction: As part of integrated systems for voltage regulation, protection and control.
Improving power quality is playing an increasingly important role in this. As an active member of the German Electrical and Electronic Manufacturers’ Association (ZVEI), ktc GmbH is actively involved in the further development of technical standards. The publication “Improving power quality in electrical networks”, which you can download here as a PDF, is a recommended guide.
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