Verification of limiter performance in modern excitation control systems

Modern excitation systems include devices for controlling or limiting machine terminal voltage (overvoltage limiters), volts per hertz ratio (V/Hz limiters), maximum machine field current (overexcitation limiters), and the reactive load absorbed by the machine (underexcitation limiters). Functional testing of these limiters before they are placed into commercial service is recommended. The Bureau of Reclamation (USA) routinely performs functional testing to determine the actual settings and operational characteristic of these limiters as part of excitation system commissioning tests on its hydroelectric generators. This paper discusses the purpose and practice of functionally testing these limiters