Three-phase transformer winding connection types are critical for large-scale power distribution, with their working principle rooted in electromagnetic induction—alternating current in the primary winding generates magnetic flux in the iron core, which then induces alternating current in the secondary winding to output voltage. As a leading manufacturer, CHH Power optimizes the two most common connection methods—star (Y) and delta (Δ)—to ensure stable performance for diverse applications. Below is a detailed breakdown of CHH Power’s three-phase transformer connection designs, including wiring rules, characteristics, and application considerations.
1. Star Connection Method (Y Connection)
CHH Power widely adopts the star connection for three-phase transformers, especially in medium-to-high voltage scenarios, due to its ability to provide a neutral line and reduce phase voltage stress.
(1) Core Wiring Structure
Taking CHH Power’s 110kV/10kV three-phase power transformer as an example, the star connection follows strict rules:
- Neutral Point Formation: One end of each of the three-phase windings (typically labeled the “neutral end,” e.g., N1, N2, N3) is connected together to form a neutral point (N).
- Terminal Lead-Out: The other end of each winding (the “line end,” e.g., A, B, C) is led out separately as the three-phase power output terminals.
- Wiring Diagram Standards: When designing wiring diagrams, CHH Power arranges the three-phase windings vertically and in parallel, with phase sequence from left to right (A→B→C). The potential direction is defined from the neutral end to the line end, while the voltage direction (between line terminals) is opposite to the phase potential direction.
(2) Key Electrical Characteristics
- Voltage Relationship: Line voltage (voltage between two line terminals, e.g., U_AB) is √3 times the phase voltage (voltage between a line terminal and neutral point, e.g., U_AN). For example, if the phase voltage is 10kV, the line voltage is 17.32kV—this makes star connections ideal for high-voltage input (e.g., 110kV grid) to reduce insulation requirements.
- Neutral Line Function: The neutral point can be grounded (e.g., solid grounding or resistance grounding) to provide a neutral line, which is essential for supplying single-phase loads (e.g., lighting in industrial plants) while maintaining three-phase balance.
(3) CHH Power’s Application Scenarios
CHH Power primarily uses star connections in:
- Medium-to-high voltage transformers (e.g., 35kV, 110kV input) for grid-side power transmission.
- Transformers requiring neutral lines, such as industrial substations that supply both three-phase motors and single-phase control circuits.
2. Delta Connection Method (Δ Connection)
The delta connection is another core design in CHH Power’s three-phase transformer lineup, favored for low-voltage, high-current scenarios due to its ability to handle higher short-circuit current and avoid neutral point issues.
(1) Core Wiring Structure
CHH Power’s delta-connected transformers (e.g., 10kV/0.4kV distribution transformers) follow a closed-loop wiring design:
- Closed-Loop Formation: The three-phase windings are connected end-to-end to form a closed triangle. Specifically, the line end of one winding (e.g., A2 of Phase A) is connected to the neutral end of the next winding (e.g., B1 of Phase B), and so on, until the loop is closed.
- Terminal Lead-Out: Three line terminals (A, B, C) are led out from the three connection points of the closed loop.
- Two Connection Variants:
- Correct Connection: The end of the previous phase (e.g., A2) connects to the start of the next phase (e.g., B1), ensuring three-phase voltage symmetry.
- Reverse Connection Risk: If the end of the previous phase (e.g., A2) connects to the end of the next phase (e.g., B2), it causes three-phase voltage imbalance—CHH Power strictly avoids this via clear terminal marking.
(2) Key Electrical Characteristics
- Voltage Relationship: Line voltage is equal to phase voltage (e.g., U_AB = U_AN). This makes delta connections suitable for low-voltage output (e.g., 0.4kV industrial power) where line voltage stability is critical.
- No Neutral Point: The closed-loop design has no neutral point, so it cannot directly supply single-phase loads requiring a neutral line (unless paired with a separate grounding transformer).
- Current Advantage: Phase current is 1/√3 of line current, allowing the transformer to handle higher line currents—ideal for high-power industrial loads (e.g., large motors).
(3) CHH Power’s Application Scenarios
CHH Power uses delta connections in:
- Low-voltage distribution transformers (e.g., 10kV/0.4kV) for industrial and mining enterprises with high-current three-phase loads.
- Transformers in scenarios where neutral points are unnecessary, such as standalone three-phase motor power supply systems.
3. CHH Power’s Design & Application Advantages
Three-phase transformers (composed of three phase units, totaling three iron cores and six windings in CHH Power’s design) offer irreplaceable value due to their high efficiency and load capacity. CHH Power leverages its connection design expertise to meet the needs of key fields:
- Strict Wiring Quality Control: CHH Power marks winding terminals clearly (e.g., line ends as A/B/C, neutral ends as N1/N2/N3) and conducts pre-delivery wiring checks to prevent connection errors—avoiding three-phase imbalance or transformer damage.
- Wide Application Coverage: From national defense and scientific research projects to schools, post and telecommunications, elevators, industrial and mining enterprises, and railways, CHH Power’s three-phase transformers (star or delta connected) provide stable power support tailored to each scenario.
By choosing the right connection method and adhering to strict design standards, CHH Power ensures its three-phase transformers deliver reliable performance in diverse power systems. Whether for high-voltage transmission or low-voltage distribution, the star and delta connections each play a vital role in meeting specific grid and load requirements.
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