Generators and Short Circuit Currents

Hello,

The short circuit between phase to phase, phase to earth will be lead to short circuit fault.

Regards,

N.Suresh

Without going deep into generator design details... A magnet moving through a coil of wire induces a current. More magnetic force, more coils, more speed all increase available current. The current is induced in the wires of the generator by the moving magnets. The moving magnets are being spun on a motor shaft. The maximum current a generator can produce is based on the size of the magnets, the coils and the RPM. The short circuit current will be limited by those factors and/or the finite impedance or the short circuit.

A generator's fault current is limited by 3 factors:

1. Sub- Transient Reactance Xd" 0 - 6 cycles

2. Transient Reactance Xd' 6 cycles - 5 seconds

3. Synchronous Reactance Xd - greater than 5 seconds

Hello guest,

1.At the time of short circuit, current flow is in kiloamps. So if proper protection is not there, winding burnout. Smoke will be observed.We cannot make a winding that can carry infinite current.

2.The output power of Generator always less than the input power because of losses. At the time of Short circuit, the required output electric power can't be provided by mechanical input. It is impossible to provide that mechanical input. To make it possible we have to rotate the rotor of generator at infinite RPM.

guest, many small generators are self excited, that is part of the output is fed into the field winding that controls the voltage out, shorting the output would cause the voltage to drop close to zero volts, thus no voltage for the field, no output. perry

If it could stay operating and keep the short circuit going it should settle at 1 p.u.