Static excitation system in synchronous generators Which components are typically used in a static excitation system?

Introduction / Context:
Excitation systems provide the field current for synchronous generators. Static exciters replaced rotating exciters in many modern plants for faster response and reduced maintenance. Identifying their building blocks helps understand control loops and reliability considerations.

Given Data / Assumptions:

• Static system means no rotating exciter machines.
• Field current is obtained by rectifying an AC source.
• Fast controllability is a design aim.

Concept / Approach:

In a static excitation system, a power transformer feeds a controlled rectifier (thyristor bridge). The rectified output provides adjustable DC to the generator field through slip rings or brushless arrangements with stationary power electronics. Thyristors enable rapid, high-power control of field current under AVR (automatic voltage regulator) commands.

Step-by-Step Solution:

Verification / Alternative check:

Plant schematics and standards (IEEE/IEC) categorize excitation systems as static when they employ stationary power electronics rather than rotating exciters.

Why Other Options Are Wrong:

Options including AC or DC exciters imply rotating machines; those are not “static” systems. A standalone transformer with a DC exciter is not a static exciter either.

Common Pitfalls:

Confusing brushless exciters (which are rotating but with rotating rectifiers) with fully static systems; ignoring the thyristor bridge as the controllable element.

Final Answer:

Transformer and thyristors (controlled rectifier)