Ac Generator Open Circuit Test

360 Words2 Pages
Project Report Synchronous Generators open and short circuit test EEE-403 Autumn-2013 Name- Md. Shawkat Kibria Kiron ID- 1020648 Open circuit Test The generator is rotated at the rated speed, •all the terminals are disconnected from loads, •the field current is set to zero first. •Next, the field current is increased in steps and the phase voltage (whish is equal to the internal generated voltage EA since the armature current is zero) is measured. Since the unsaturated core of the machine has a reluctance thousands times lower than the reluctance of the air-gap, the resulting flux increases linearly first. When the saturation is reached, the core reluctance greatly increases causing the flux to increase much slower with the increase of the mmf. Open circuit test characteristic graph Short Circuit Test The short-circuit test provides information about the current capabilities of a synchronous generator. It is performed by 1) Generator is rotated at rated speed. 2) Adjust field current to 0. 3) Short circuit the terminals. 4) Measure armature current or line current as the field current is increased. Short circuit test characteristic graph From both tests, here we can find the internal machine impedance (EA from OCC, IA from SCC): Since Xs >> RA , the equation reduces to: Short Circuit Ratio Ratio of the field current required for the rated voltage at open circuit to the field current required for rated armature current at short circuit. OCC and SCC A drawback of this method is that the internal generated voltage EA is measured during the OCC, where the machine can be saturated for large field currents, while the armature current is measured in SCC, where the core is unsaturated. Therefore, this approach is accurate for unsaturated cores only. The approximate value of synchronous reactance varies with

More about Ac Generator Open Circuit Test

Open Document