Time Response of a De-energizing Aerospace Synchronous Generator

The electrical power generation capacity of aerospace electric machines has grown considerably in both modern and future aircraft. While electrical power provides many performance and efficiency advantages, the added capacity also increases the available electrical fault current. Consequently, it is critical to understand the response of the electric machine to a fault and design protection schemes to de-energize the machine in order to mitigate any potential damage to the aircraft.This paper experimentally compares the response time of a wound-field synchronous generator when simultaneously shorting the terminal windings and opening the exciter field windings for no-load and loaded conditions. These results are compared against the response times to fault conditions in which the generator continues excitation throughout the shorting event. This experimental set can be used to empirically evaluate the magnitudes of peak current and the stored energy of the wound-field brushless electrical generating system. A subset of the experimental matrix is used to simulate a crowbar across the generator armature windings.