AFGS�87219B APPENDIX A
VERIFICATION LESSONS LEARNED (A.4.2.9.3)
A generator must be tested to demonstrate compliance with all of its performance requirements. This assures that the generator will operate in its actual environment. Every qualification test program results in some design changes that provide a better system in the field.
A.3.2.9.4 Converters.
a. DC to AC converters (inverters) shall be in accordance with: ------------.
b. When equipment that is essential for safe flight derives power from an inverter, a spare inverter shall be provided. Changeover from the main inverter to the spare shall be automatic in the event of main inverter failure. Spare inverters may be used as operative units to supply power to nonessential loads, but these loads shall be dropped in the event of main inverter failures.
c. AC to DC converters shall be in accordance with: ------------. When the outputs of two or more AC to DC converters are parallel to supply a common DC bus, no single unit shall be loaded beyond its rating for the worst-case load unbalance or failure mode which can occur.
REQUIREMENT RATIONALE (A.3.2.9.4)
The EPS is often required to supply power of a type different from that provided by the primary source. In this event a means of power conversion is needed. Typically, the conversion is from
115-volt, 400 Hz power to 28 volts DC (rectification) or from 28-volt DC to 115-volt, 400 Hz,
3-phase or single-phase (inversion).
REQUIREMENT GUIDANCE
a. Requirements for DC to AC converters (inverters) should be based on MIL-PRF-7032.
This specification covers both rotary and solid-state types.
b. Requirements for AC to 28 Volt Unregulated DC should be based upon MIL-C-7115.
Older systems may refer to the inactive MIL-DTL-26517. This specification should only be used for AC to DC converter (transformer-rectifier) replacepent, and not new designs.
REQUIREMENT LESSONS LEARNED (A.3.2.9.4)
Converters are frequently used in the system to provide voltages other than the ones provided by the main generators. This results in an electrical system that is more efficient overall. Many aircraft use off-the-shelf equipment which do not operate on normal aircraft power, and converters are the best way to provide the electrical power these equipments need.
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