Generator Excitation System

The THYRIPOL 520/1800 R excitation system is one of the main strategic systems in power plants used in gas and steam units. It is manufactured by MECO under SIEMENS license for medium and large-scale generators.

 To achieve redundancy (2×100%) and increase the system reliability, two separate working channels including two AVR controllers and two rectifiers have been used. In case of an error or at operator command, while maintaining the normal system operation and without changing the machine terminal voltage, one channel replaces the other immediately and without interruption.

In the power circuits, two AC switches are provided to isolate the excitation system panel from the input which results in easy system maintenance.

In implementation of excitation control system based on the generator physical limitations and customer needs, many control functions and limits such as over-excitation and under-excitation limiters, along with stator current limiter, voltage per Hz, PSS power system stabilizer, reactive power controller and power coefficient controller are taken into account.

General system description:

The protection and maintenance of devices in power plants is crucial for saving capital and ensuring reliable electricity production. If a device does not have proper protection circuits and systems, or if its protection system fails for any reason, it may suffer severe damage during operation in case of faults. This may make the device irreparable, and result in high costs of replacement and repairs, as well as long-term loss of electricity production. Generators are one of the essential equipment of power plants, and any problems with them will force the system to disconnect the units from the grid and stop producing electricity for a long time.

Features of Generator Excitation System
    1. Easy and cheap set up, and maintenance via compact and modular design incorporating the installation of excitation system components in separate panels
    2. Automatic voltage regulator (AVR) and manual or field current regulation (FCR)
    3. OP touch panel with a set of analog meters to enable system monitoring and run all operations in local mode
    4. Forced air system including fan to prevent heat loss
    5. Advanced equipment such as S7-SIMATIC control racks and DC motor drive (SIMOREG) incorporating features including:
    • Modular design with system control board technology
    • PC / PG connectivity
    • Appropriate software package to adjust system parameters
    • Control and operator panel
    • A recorder logging events in the system memory by connecting the system to PC / PG and drawing the corresponding diagrams
    • Over voltage protection to strengthen system security with AC switches and circuit breaker protection
    • Full redundancy (2*100%) design to ensure increased system reliability
    • Achieving the control loops required sample values via current and voltage transformers at the generator output

Excitation system specifications


See 520/1800R

Output power


Excitation voltage at rated load


System response time


Excitation current at rated load


Impulse current test


Maximum input voltage


Thyristors type

5ST P27 H180



Rated losses


Cooling system

Forced air cooling

IP protection degree


Scroll to Top