1. A 3 phase, wye connected synchronous generator rated at 10kVA, 230V has a synchronous reactance of 1.2 ohms per phase and an armature resistance of 0.5 ohms per phase. Calculate the percent voltage regulation at full load if the power factor is 0.8 lagging. Draw the phasor diagram. Then, determine the power factor such that the voltage regulation is zero on full-load.
2. 150kVA 480 V, 60 Hz wye connected synchronous generator with a rated field current of 5 amps was tested and the following data was taken:
The open circuit terminal voltage at rated field current was 530 volts
The armature current at the short circuit condition was 300A
When a DC voltage of 15 volts was applied to the two terminals, 30 amps was measured. Find the values of the armature resistance and synchronous reactance that would be used in the generator model at rated conditions.
3. A 480 volt, 60 Hz, Wye connected synchronous generator has eight poles. The synchronous reactance is 1.3 ohms. The full load armature current is 80A at 0.85 pf lagging. Friction and windage losses are 2kW and core losses are 1kW. Assume the armature resistance is negligible. The field current has been adjuested to make the terminal voltage 480V at no load. Determine the following:
Speed of rotation
Terminal voltage with at rated current with 0.85 pf lagging, rated current with unity power factor, and rated current with 0.85 pf leading. Draw a phasor diagram for each.
What is the efficiency when operated at rated current and 0.8 pf lagging?.
What is the shaft torque at full load?
What is the voltage regulation at 0.8 pf lagging?