The generator excitation system is based on a DC rectifier system that supplies voltage (rectified) to the generator rotor. This system consists of smaller components called rectifier elements, which determine the characteristics of the rectifier.
Excitation systems are classified into three main types according to the source of excitation power:
1- DC Excitation Systems
2- AC Excitation Systems
3- Static Excitation Systems
The excitation systems produced by MAPNA Electric & Control, Engineering & Manufacturing Co. (MECO) have both dynamic and static varieties.
1- The indigenous system developed by MECO with the brand name MAPEX (MAPNA Excitation System)
2- Under the license of Siemens Company
3- Under the license of ABB Company
Siemens-licensed system
Home-grown MAPEX system
ABB-licensed system
Currently, MECO produces the EAA excitation system under the license of the Italian company EAA in three ranges.
MAPEX-A | MAPEX-E | MAPEX-F | EAA | EAA | EAA | SIEMENS | ABB | TYPE Description |
Brush | Brush | Brush | Brushless | Brushless | Brush less | Brush | Brush | Synchronous Machine |
100 | 200 | 470 | 7.5 | 13.125 | 32.25 | 200 | 200 | Rated Power (MVA) |
13800 | 15750 | 20000 | 6000 | 11000 | 11000 | 15750 | 15750 | Rated Stator Voltage (V) |
50 | 50 | 50 | 50 | 50 | 50 | 50 | 50 | Rated frequency (Hz) |
0.85 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | Rated Power Factor (pu) |
873 | 1417 | 3629 | 722 | 689 | 1640 | 1559 | 1559 | Rated Field Current (A) |
Excitation Transformer | ||||||||
670 | 1150 | 3950 | 2 | 2 | 2 | 1150 | 1150 | Rated Power (KVA) |
13800 | 6600 | 20000 | 400 | 400 | 400 | 6.6 | 6.6 | Rated Converter NoLoad Voltage (V) |
400 | 520 | 692 | 95 | 95 | 95 | 520 | 486 | Rated Transformer sec. current (V) |
6 | 6 | 6 | 3.8 | 3.8 | 3.8 | 6 | 6 | Short Circuit Impedance (%) |
Dy5 | Dy5 | Dy5 | Yd11 | Yd11 | Yd11 | Dy5 | Dy5 | Vector Group |
Excitation Data | ||||||||
960 | 1559 | 4345 | 7.7 | 9 | 9.1 | 1417 | 1417 | Rated Field Current |
250 | 296 | 426 | 45.5 | 31.5 | 41.3 | 296 | 326 | Rated Field Voltage |
1472 | 2267 | 6952 | 13.86 | 18.45 | 15 | 2250 | 2267 | Ceiling Field Current (A) |
500 | 592 | 852 | 81.9 | 64.5 | 114 | 520 | 592 | Ceiling Field Voltage (V) |
The excitation system is a vital component of the power plant that connects to the generator. Considering its importance, MECO designed and built its own excitation system, called MAPEX (MAPNA Excitation System), and tested it successfully. The system was also installed and commissioned successfully in the second steam unit of Parand power plant in Tehran and Ferdowsi power plant in Mashhad.
The experts of this company, after years of installing and operating power plant excitation systems from leading and reliable global brands in different parts of Iran and gaining experience in assembling the power and control panels, managed to achieve the technical knowledge of designing and building this system by making the first sample of MAPEX. Acquiring indigenous technical knowledge in this area is one of the most important strategic projects of a power plant that is designed and built by relying on indigenous knowledge and expertise.
The complete manufacturing of sensitive power equipment and advanced control and electronic devices of this system has been done by the experts and specialists of MECO Company in accordance with the international standard IEEE421.5. Currently, this product can meet the need of class E power plants (with a power of 200 megavolt amps) for an excitation system with a current of 1417 amperes.
Meanwhile, the company is planning to design, construct, and operate excitation systems of class F power plants (with a power of 470 megavolts and a current of 4000 amps) in the near future.
