Aircraft Utilization Equipment Requirements
MIL-STD-704 also covers the requirements for aircraft utilization equipment. Below you’ll find an overview of all these requirements.
The equipment used in a military aircraft must be compatible with the power characteristics specified in the MIL-STD-704 standard. The standard sets the input requirements for military aircraft power supplies, compliance to the standard ensures compatibility and optimal performance between the source and utilization equipment. Such equipment shall not require a power of better quality than specified by the standard.
The utilization equipment shall also be compliant with the requirements of the applicable aircraft specifications for the control of electromagnetic interference and voltage spikes caused by power switching, lightning, and electromagnetic pulses. MIL-STD-704 does not cover voltage spikes and electromagnetic interference.
Besides power compatibility, another crucial requirement of aircraft utilization equipment is that it shall not cause the power characteristics at its input terminals to exceed the limits specified in the standard, as well as providing the level of performance required by its detailed specification for each operating condition.
Regardless of the operating conditions of the electrical system, the utilization equipment should not negatively affect the electrical system or cause it to malfunction.
The operation modes addressed in MIL-STD-704 are: normal operation, abnormal operation, transfer operation, emergency operation and starting opoeration.
As per MIL-STD-704, any utilization equipment that loses power (AC or DC) or one or more phases of AC power must not result in an unsafe condition or damage to that equipment.
AC Power Utilization
MIL-STD-704 also provides more specifications for utilization equipment using AC power as per below:
- For equipment requiring more than 0.5 kVA of 400 Hz AC power, the configuration shall be designed to utilize three-phase steady-state balanced power.
- Utilization equipment whose total load is greater than 30 kVA should have a load unbalance no greater than 3.33% of its total three-phase load.
- Single-phase AC power should be used only on a line-to-neutral basis.
- AC power should not be half-wave rectified.