Testing electronic systems GTD
Testing electronic systems GTD

Testing electronic systems GTD

In testing of electronic systems for the generation of electromagnetic interference is necessary to assess the levels of the electric field generated by the system in the frequency range 0,15. 1215 MHz, as well as electromagnetic interference in the power supply and connecting cable systems in the frequency range 0,15. 30 MHz.

Investigations of the electric field strength created by the system are carried out in shielded rooms, the dimensions of which should allow the installation of measuring antennas at a distance of not less than 2 m from the walls of the room and 1 m from the equipment under investigation. The investigated system is placed on a grounded table. To cover the entire frequency range, pin, biconical, logarithmic and other types of antennas are used, connected in series through a shielded cable to the electromagnetic interference meter. When testing for the susceptibility of electromagnetic interference, it is necessary to simulate the effect of magnetic and electric fields. The magnetic field is created at a distance of 0,15 m from the block using an alternating current with an effective value in the 20 A wireductor at a frequency of 400 Hz. In addition, it is necessary to simulate a magnetic field in the range of sound frequencies around the connecting cables of the equipment under test. The effects of the electric field on the blocks, power circuits and connecting cables are created in the radio frequency range of electromagnetic interference: for the supply circuits 0,09. 30 MHz, for 0,15 blocks and interconnect cables. 1215 MHz.

Investigation of the effect of electromagnetic interference from lightning discharges. Lightning, developing near DA or directly damaging it, creates induced voltages in electrical circuits inside the equipment blocks and in communication lines between them. The voltage pulses induced in the electrical circuits have a complex shape. This is explained by the fact that the pulses that occur during lightning are the result of the imposition of a number of processes of interaction of the electromagnetic field with metal elements of the DA structure and the electrical circuits of interblock and intra-unit connections.

Avionics, to which conditions may the impact of lightning discharges, should be tested in the laboratory for resistance to pulse voltages of three types: "long", "short" and "oscillating" waves. Each pulse shape is determined by the specific physical factors arising from lightning.

Depending on the location of the electronic control on the plane defined by the required stiffness category. By descent

Nome standard provides four categories, differing amplitude pulses. For example, the most vulnerable areas on the plane, the fourth category, which has an amplitude of vibrational In 3200 wave.

Testing Process

The test complex allows automatic selection of the type of generated wave, the formation of a pack of test pulses of the required polarity and their registration. A block diagram of an automated complex is shown in 5.6.

During the test, the electronic controller fixed moments of the failed operation, recovered and non-recoverable failure, which is usually associated with electrical injuries elements of microelectronics.

Investigation of the effect of instability on-board power supply. To investigate the effect of steady and transient modes onboard electric DC nominal voltage 27 in the functioning of the electronic control systems GTD simulator uses an automated on-board power supply. The simulator provides a variable dc voltage pulse generators and value ± 100 ± 600 B and sinusoidal voltages.

View generated cycles of stress changes, and ripple pulse determined by the requirements of the standard. The simulator allows you to change automatically according to the program the output voltage 0. In .80 and issue fixed voltage values ​​0, 27, 50, 60, 70 and 80 B. At fixed DC voltage can be superimposed high voltage pulses 0. In .600 and ripple voltage in the range of 5. 100 kHz.

During the tests, the electronic regulator on the impact of electrical noise immunity level is evaluated for compliance with the requirements specified in the terms of reference, or conducted research to assess the level of noise immunity of the electronic limit controller and choice of effective remedies.

In the case of non-performance electronic control set requirements made its revision. This may require the introduction of additional digital or analog filters, nonlinear resistors, additional shielding of cables and blocks, changing circuit ground transfer electronic controller in a radio interference suppressed aircraft and other areas.

Investigation of the influence of climatic, mechanical and other types of impacts

Climatic effects. For the temperature test conducted to determine the performance of electronic controls with temperature in a given interval (currently on -60 or -40 to + 125 ° C). An important feature of the electronic test controller on exposure to elevated temperatures is the evaluation by termometrirovaniya thermal regime of the most thermal stress elements within the electronic controller.

Test electronic regulators of the effect of reduced pressure is carried out at different temperatures. The product is considered to be satisfactory if during his stay under reduced atmospheric pressure ensures reliable switching of electrical circuits are not observed the phenomenon of "crown" and the overlap between live elements and parameters of the electronic controller is within the rules.

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