170614_FA3099-17-R-0005_Questions_and_answers.pdf

FA3099-17-R-0005 Question and Answers.

1. Interface standards MIL-STD-704 and ISO 6858 specify the maximum acceptable output voltage limits of a 28VDC GPU at the point of aircraft connection (plug/receptacle connection); these maximum limits are in terms of an acceptable output voltage range. For example, during engine start the voltage at the point of connection (plug head) is not to be less than 12 volts for a short time (seconds) at which time the plug head voltage must not be below 20 to 22 volts, dependent upon the applicable standard. This is the stipulated minimum unit output voltage at the plug head regardless of starting current; for this requirement a starting current of 1600 amps and a cable length of 30 feet has been specified.

Likewise, at the continuous 400 amp rating of the advertised Hobart GPU 400T provides an output voltage regulation of ± 0.5% of nominal when the input voltage is varied 480V ± 10%. It is assumed that this regulation is required. Please confirm.

A: This is correct, the regulation is required.