Transformer tap changer

Transformer tap changer (Spanish: Cambiador de Derivaci ó n, English: Tap Changer) is the core component for regulating the output voltage of transformers. It is divided into two types: on load tap changer (OLTC/CDC) and no-load tap changer. Its working principle and significance are directly related to the power supply stability, equipment compatibility, and operation and maintenance costs that Latin American customers are most concerned about. The following is a simplified professional analysis:

1、 Core working principle

1. No load tap changer (power-off adjustment)

Principle: After the transformer is powered off, the "tap changer" (terminals with different turns) on the winding is manually switched to change the number of turns in the primary winding, thereby adjusting the transformation ratio (U ₁/U ₂=N ₁/N ₂), and ultimately achieving the rated output voltage.

Key features: Simple structure, low cost, requiring power interruption during switching, only suitable for scenarios with stable load and low requirements for power supply continuity (such as rural power grids in Latin America and small shops).

2. On load tap changer (live regulation, core requirement for Latin American industry)

Principle: During the operation of the transformer with load, an uninterrupted transition of tap switching is achieved through a "transition resistor" (to avoid arc erosion), and the power supply is maintained continuously during the switching process. At the same time, the winding turns are precisely adjusted through mechanical/electronic control to stabilize the output voltage.

Key features: Supports multiple gears (commonly 17/21 gears), high-precision (± 1%) voltage regulation, suitable for scenarios with frequent voltage fluctuations in the power grid (such as mining in Chile and manufacturing in Ecuador), and core parameters need to be labeled with adjustment ranges (such as ± 10%).