INTRODUCTION
This paper sets forth the minimum performance standards for airborne static („DC to DC“) electrical power converter equipment then used as a part of a navigation or communication system.
Compliance with these standards is required as a means of assuring that the equipment will satisfactorily perform its intended function under all conditions normally encounted in routine aeronautical operations.
Inasmuch as the measured values of a radio equipment performance characteristics may be a function of the method of measurement, standard test conditions and methods of test are also recommended in this paper.
MINIMUM PERFORMANCE STANDARDS FOR AIRBORNE STATIC („DC TO DC“) ELECTRICAL POWER CONVERTER
1.0 GENERAL STANDARDS
1.1 Ratings of Components
The equipment shall not incorporate its design any component of such rating that, when the equipment is operated throughout the range of the specified environmental test, the ratings established by the manufacturer of the component is exceeded.
1.2 Effects of Test
The design of the equipment shall be such that the application of the specified test produces no discernable condition which would be detrimental to the reliability of equipment manufactured in accordance with such design.
2.0 MINIMUM PERFORMANCE STANDARDS UNDER STANDARD TEST CONDITIONS
The test procedures applicable to a determination of the performances of the airborne static („DC to DC“) electrical power converter equipment are set forth in Appendix „A“ of this paper.
2.1 Nominal Output Voltage and Current
The nominal output voltage and current shall not be less than that specified by the manufactuer’s ratings. Further, the equipment shall be capable of delivering at least 10% more output power than the manufacturers specified rating for a period of two (2) hours.
2.2 Regulation
Regulation under standard conditions shall not exceed 12%. For the purpose of this standard, regulation is defined as:
2.3 Ripple
Ripple in the output DC voltage at maximum rated output load shall not exceed 1/10% of the output voltage when shunted by a 2 mfd capacitor and the ripple on the DC input leads is equal to 2 volts peak to peak at a frequency of 400 cps. For equipment designed for operation on 13.75 volts DC, the ripple on the input leads need not exceed 1 volt peak to peak.
2.4 Over Voltage
There shall be no permanent damage to any of the solid state devices (transistors) or the components when the power converter is delivering full rated output power and is subjected to the following over voltage conditions:
(a)The input DC voltage is increased to 50% above the standard operating voltage for a duration of not less than five minutes.
2.5 Short Circuit Conditions
There shall be no degradation of the power converter or its components as a result of a sustained short circuit applied separately to each output of a multiple output power converter, or simultaneously to all DC outputs for a period of not less than one minute. Within five minutes after removal of the short circuit condition, the equipment shall be capable of continuous operation at the manufacturer’s rated output load for a period of eight hours without, degradation of performance.
2.6 Emission of Radio Frequency Energy
The emission of radio frequency energy at discreet frequencies within the range of 90 kc to 1500 Mc shall not exceed 200 microvolts between any cable terminal to ground.
Note: It is recognized that the radio frequency emissions having a level considerably less than the maximum permitted by the above standard are capable off interfering with the operation of other electronic equipment in an aircraft installation. It is also recognized that the method of reducing the level of emission of radio frequency energy to much lower values are known. However, at the present state of the art, large and expensive filters are often required in addition to the exercise of care in the mechanical and electrical design of equipment. The end result is often a compromise between what is desired and cost.
In view of the above, the emission standards were set at a level which can be met by the exercise of reasonable care in design and yet effect the reduction in the present overall interference problem. Lower emission levels are desirable and it is, therefore, recommended that the equipment manufacturers make a determined effort to reduce the level of emission from electronic equipment, to the lowest practicable value below that specified above.
2.7 Dielectric Strength
The equipment shall withstand without evidence of damage the application of a sinusoidal voltage between each transformer output winding and frame for a period of five seconds. The RMS value of the sinusoidal voltage applied shall be either five times the maximum operating voltage existing across that winding during operation when delivering full rated output, or 500 volts, whichever is greater. During the application of this test, all diodes, transistors, and capacitors may be disconnected.
3.0 MINIMUM PERFORMANCE STAND ARDS UNDER ENVIRONMENTAL TEST CONDITIONS
The test procedure applicable to a determination of the performance of radio equipment under environmental test conditions are set, forth in RTCA Paper 100-54/D0-60, „Environmental Test Procedures-Airborne Radio Equipment,“ and amendment Paper 256- 58/ EC-366 dated November 13, 1958. This paper outlines environmental test procedures for equipment designed to operate under three environmental test conditions as specified therein under Procedures A, B, and C. Only airborne static („DC to DC’) electrical power converter equipment which meets the operating requirements outlined under Procedure A or Procedure B of this paper, as amended, is applicable under this standard.
The applicable electrical test procedures are set forth in Appendix „A“ of this standard.
3.1 Low Temperature Test
When the equipment is subjected to the low temperature test and, with primary power voltage 10% less than standard test voltage applied, the following requirements shall be met:
(a)The output voltage shall not vary more than 121/2% from that obtained at standard test conditions.
(b)The requirements of paragraph 2.3 shall be met.
3.2 Altitude Test
When the equipment is subjected to the altitude test, the requirements of paragraphs 2.1, 2.2, and 2.3 shall be met.
3.3 Humidity Test
After subjection to humidity and within fifteen (15) minutes from the time primary power is applied, the requirements of 2.1, 2.2, and 2.3 shall be met.
3.4 High Temperature Test
When the equipment is subjected to the high temperature test and with primary power voltage 10% higher than standard test voltage applied, the following requirements shall be met:
(a)The output voltage shall not vary more than 121/2% from that obtained at standard test conditions.
(b)The requirements of paragraphs 2.1, 2.2, and 2.3 shall be met.
3.5 Temperature Variation Test
When the equipment is subjected to the temperature variation tests, the requirements of paragraphs 2.2 and 2.3 shall be met.
3.6 Vibration Test
When the equipment is subjected to the vibration test, the requirements of paragraphs 2.2 and 2.3 shall be met.
3.7 Shock Test
(a)Following the application of 15 G shocks, the requirements of paragraphs 2.2 and 2.3 shall be met.
(b)Following the application of 30 G shocks, the power converter shall have remained in its mounting by its intended means and no parts of the equipment or its mounting shall have become detached and free from the equipment.*
3.8 Low Voltage Test
(a)When the primary power voltage(s) is 80% of the standard test, voltage(s), the equipment shall operate electrically.
(b)Gradual reduction of the primary voltage(s) from 80% to 50% of standard test voltage(s) shall produce no condition detrimental to the reliability of the equipment.
(c)Gradual reduction of the primary power voltage(s) from 50% to 0%, of standard test, voltage(s) shall produce no evidence external to the equipment of the presence of fire or smoke.* * Test tests may be conducted after other tests are completed.