We design a suit of aviation AC excitation generator system, it insures the output voltage is constant frequency and constantvoltage.
我们设计了一套航空用交流励磁发电机系统，以保证输出电压恒频恒压。
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To make the measurement, a constantvoltage is applied for a predefined period, usually 60 seconds, and the resulting current is measured with a picoammeter or electrometer.