AFGS-87219 Electrical Power Systems, AircraftThis specification establishes the performance requirements and verifications for electric power subsystems EPS for aerospace vehicles, including aircraft, helicopters, and missiles.

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AFGS�87219B APPENDIX A

A.3.3 Electromagnetic interference (EMI).

The electromagnetic interference requirements for the EPS shall be as follows: ------------.

REQUIREMENT RATIONALE (A.3.3)

EMI requirements for the electric power subsystem must be established which are consistent with, and in support of, the EMI requirements for the total aircraft system.

REQUIREMENT GUIDANCE (A.3.3)

Specify the applicable requirements of MIL-STD-461 for the EPS and its components. EMI engineers within AFLCMC can provide guidance for a particular application. Tailoring of the conducted emission requirements of MIL-STD-461 to be compatible with the harmonic distortion requirements will be required.

REQUIREMENT LESSONS LEARNED (A.3.3)

EMI-related problems have resulted from high-voltage, short-duration spikes on power lines. These spikes are usually load-induced and are most often caused by the switching of inductive loads. Spikes are a concern of the EPS because they can be transmitted to susceptible equipment via the EPS distribution circuits. Spike compatibility can be ensured by limiting spike levels in accordance with MIL-STD-464 and by requiring equipment to meet the spike susceptibility requirements of MIL-STD-461. Inductive coils should have diode suppression to minimize EMI effects.

A.4.3 Electromagnetic interference.

Compliance with the electromagnetic interference requirements of 3.3 shall be verified by tests as follows: ------------.

VERIFICATION RATIONALE (A.4.3)

Appropriate testing of the EPS components and the installed subsystem is the only means of ensuring that EMI requirements are met.

VERIFICATION GUIDANCE (A.4.3)

Specify the applicable test requirements of MIL-STD-461 for the EPS and its components. Ensure that the EMI test program for the total aircraft adequately covers the requirements for the installed electric power subsystem. Consult with EMI engineers within AFLCMC for additional guidance.

VERIFICATION LESSONS LEARNED (A.4.3)

Modification of MIL-STD-461 limits will be needed to prevent over-design of the generator output filtering. Generally, the output harmonic distortion requirements of MIL-STD-704 are adequate.