RU2352502C1 - Device to check up aircraft resistance to lighting - Google Patents

Abstract

FIELD: transport, aviation.

SUBSTANCE: proposed device comprises a charging device, measuring system incorporated with the discharge and aircraft circuits, discharge circuit consisting of a bridge, power accumulating capacitor, generating elements, two switching circuits, all connected in series. The first of aforesaid switching circuits represents a controlled spark discharger, while the second one operates with a time delay relative to the starting of aforesaid controlled spark discharger. The second one features operation voltage making, at least, 0.2 of the operating voltage of the controlled spark discharger. First electrode of the first switching circuit and first electrode of the second switching circuit are interconnected by a 1 to 2 cm-long conductors, thus forming a common-electrode switching circuits. Second electrode of the controlled spark discharger and common electrode are enveloped by a metal shield representing a cup with its bottom connected to second electrode of the controlled spark discharger and to high-voltage output of the said power accumulating capacitor. Second electrode of the second switching circuit is connected to the discharge circuit generating elements.

EFFECT: reduced level of noise signal.

2 cl, 8 dwg

Description

The invention relates to testing equipment and can be used in tests to determine the voltage and currents induced by lightning in inter-unit electrical harnesses of objects for various purposes, namely in the field of testing lightning protection of aircraft using high-voltage test installations.

The prior art.

A known test setup containing capacitor energy storage devices for producing pulsed components of the test current and a battery for producing a constant component, controllable spark gaps, current pulse generating elements, shunt devices (see Kuzhekin I.P., Larionov V.P., Prokhorov E .N. Lightning and lightning protection. - M :, “ZNAK”, 2003, p. 280-283). Schematic diagram of the test setup is shown in figure 3.

Also known installation, including a current pulse generator, instrumentation, fiber optic transmission line, an isolated power source, an earthed plane, connecting conductive wires (SAE ARP5416. Society of Automotive Engineers. Aerospace Recommended Practice. Aircraft Lightning Test Methods. 2005). Schematic diagram of the test setup is shown in figure 4.

A known installation, including a measuring system of pulsed currents and voltages, current-carrying and measuring conductors, a current pulse generator, consisting of a capacitor energy storage device, a high-voltage controlled spark gap, a control unit. Schematic diagram of the test setup is shown in figure 5. A current pulse is injected into the test object through the spark gap, and the currents and voltages induced in the inter-unit harnesses of the equipment under test are simultaneously oscillated (RTCA / DO-160D. "Environmental Conditions and Test Procedures for Airborne Equipment", Section 22 "Lightning Induced Transient Susceptibility", 2004 .).

In the above-described installations for studies on lightning resistance when spark gaps are triggered, a voltage jump occurs on the circuit elements with a rather steep front, which leads to high-frequency oscillatory processes in the discharge circuit, the parameters of which are determined mainly by spurious capacitive couplings between the elements of the discharge circuit adjacent to the controlled spark gap, and other elements of the circuit in which oscillatory processes develop, while eliminating the generation of an interference signal from natural methods fail.

Closest to the proposed installation is the installation for testing aircraft for lightning resistance (RF patent No. 44104, January 16, 04, "Installation for testing aircraft for lightning resistance"), which allows to separate the interference signal from the useful signal, including a capacitor energy storage unit, a control unit , a measuring system, forming elements, two switches connected in series to the discharge circuit, the first of which is a controlled spark gap, and the second one with a glow discharge, with a time delay relative to the start of switching on the managed spark switch. The response delay of the second switch is 1-10 μs in time relative to the start of switching on the controlled spark switch. The operating voltage of the second switch is not less than 0.2 of the operating voltage of the controlled spark switch. Schematic diagram of the test setup is shown in Fig.6.

The main factor determining the occurrence of spurious current fluctuations is the charging of current-carrying circuits in section A-B (see Fig. 6) of the discharge circuit when a controlled spark gap is triggered, which has short response times and the presence of capacitive connections between the current-carrying elements of the discharge circuit. The introduction of a second switch with a glow discharge with a response time of 1-10 μs allows you to carry out the impact at a time when spurious oscillations are reduced to 3-5% of the level of the useful signal.

Due to capacitive coupling, the interference signal can exceed the useful signal by two orders of magnitude. This circumstance leads to the fact that the recording devices operate with very large overloads, and in some cases the level of the interference signal preceding the useful one can lead to damage to the input path of the measuring device.

The technical problem to which the invention is directed is to develop an installation for testing aircraft for lightning resistance, in which the weakening of stray capacitive connections of the switch circuit section with the rest of the circuit elements and the test object is carried out with the simultaneous separation of the interference signals and the useful signal in time, due to which ensures a decrease in the level of the interference signal to a level equal to or slightly higher than the useful signal.

To achieve this technical result, in an installation for testing aircraft for lightning resistance, including a charger, measuring systems for the discharge circuits and the test object, a capacitor storage device, a discharge circuit consisting of a series-connected shunt, the test aircraft, forming elements, two switches, the first of of which is a controlled spark gap, and the second switch is triggered with a time delay relative to the start of switching on a controlled spark mutator, the operating voltage of the second switch is not less than 0.2 from the operating voltage of the controlled spark switch, according to the invention, the first electrode of the first switch and the first electrode of the second switch are connected by a conductor of a length of not more than 1-2 cm, forming switches with a common electrode. The second electrode of the controlled spark gap and the common electrode are enclosed in a metal screen made in the form of a cup with a bottom connected to the second electrode of the controlled spark gap and connected directly to the high-voltage output of the capacitor energy storage device.

The distance from the first electrode of the second switch to the edge of the glass should be at least two diameters of the glass. The second electrode of the second switch is connected to the forming elements of the discharge circuit.

The discharge circuit made using commutators with a common electrode, as well as shielding the common electrode with a metal shield connected to the second (high-voltage) electrode of the controlled spark gap and connected directly to the high-voltage output of the storage capacitor, are significant distinguishing features, which reduces the spurious capacitive coupling Cn section of the circuit from the capacitive energy storage to the second switch with the test object, leading to reduced st 30-50 times the level of high frequency noise with a reduction of its duration to 1-2 ms.

The proposed installation for testing aircraft for lightning resistance is illustrated in figure 1-2.

In figure 1. the claimed scheme of the installation for testing aircraft for lightning resistance, where

1 - charger;

2, 3 — measuring systems of the discharge circuits and the test object;

4 - discharge circuit;

5 - test object - test aircraft;

11 - switches with a common electrode;

Sn is the capacitance of the capacitor bank;

Lf, Rf - elements forming a discharge pulse;

Rш - current shunt;

Cn - parasitic capacitance.

In figure 2. the circuit diagram of switches with a common electrode, where

6 - the first switch (controlled spark gap);

7 - the second switch (switch with a glow discharge);

8 - the first electrode of a controlled spark gap;

9 - the first electrode of the switch with a glow discharge;

10 - conductor connecting the first electrodes of both switches.

12 - common electrode;

13 - second (high voltage) electrode of a controlled spark gap;

14 - metal screen;

15 - the second electrode of the switch with a glow discharge.

In figure 3. presents a diagram of the installation for testing aircraft for lightning resistance, where

5 - test object;

C1, C2, C4 - capacitor banks;

R2, R3 - forming resistance;

LI, L2, L3, L4 - forming inductances;

СР1, СР2, СР3, СР4 - controlled spark arresters;

ШУ1, ШУ2 - shunt devices;

Cn - parasitic capacitance between the elements of the discharge circuit.

In figure 4. shows a schematic diagram of an installation for testing aircraft for lightning resistance given in SAE ARP5416, where

5 - test object;

17 - current pulse generator;

18 - instrumentation;

19, 20 - fiber optic receiver, transmitter;

21 - an isolated power source;

22 - connection of the helicopter to a grounded plane.

5. depicts a setup for testing aircraft for lightning resistance, given in (RTCA / DO-160D), where

5 - test object;

V is a high voltage source of constant voltage;

RЗ - charging resistance;

R1 - additional resistance,

R2 - load resistance

L1 - forming inductance;

SR - controlled spark gap;

Cn - parasitic capacitance between the elements of the discharge circuit.

In Fig.6. shows a diagram of the installation for testing aircraft for lightning resistance given in the patent of the Russian Federation No. 44104, where

2, 3 — measuring systems of the discharge circuits and the test object;

5 - test object;

6 - controlled spark gap;

7 - switch with a glow discharge;

16 - control unit;

С _Н - capacitance of a capacitor bank;

L _f , R _f - forming elements;

R _W - current shunt.

On figa, 7b presents a typical ratio of noise levels and voltages induced in the on-board circuits when tested in the installations shown in SAE ARP5416 and in the patent of the Russian Federation No. 44104, where

23 - voltage. AT;

24 - time, μs;

25 - interference signal;

26 is a voltage waveform in an electric circuit.

On Fig. the ratios of noise levels and voltages induced in on-board electrical circuits during tests on the inventive installation, where

23 - voltage. AT;

24 - time, μs;

25 - interference signal;

26 is a voltage waveform in an electric circuit.

The implementation of the inventive installation.

Installation for testing aircraft with lightning resistance (see Fig. 1), includes a charger 1, measuring systems of the discharge circuit 2 and the circuit of the test object 3, a capacitor storage device for energy Sn, discharge circuit 4, consisting of a series-connected shunt Rш, the test aircraft 5 of the forming elements Lf, Rf, two switches (see figure 2), the first of which 6 is a controlled spark gap, and the second switch 7 is a time-delayed switch relative to the start of the controlled spark switch ra, the voltage of the second switch actuation is not less than 0.2 at the discharge voltage of the spark-managed switch. To reduce the level of spurious interference, the first electrode 8 of the first switch 6 and the first electrode 9 of the second switch 7 are connected by a conductor 10 with a length of not more than 1-2 cm, forming switches 11 with a common electrode 12. The second electrode of the controlled spark gap 13 and the common electrode are enclosed into the metal screen 14, made in the form of a glass with a bottom connected to the second electrode of the controlled spark gap and connected directly to the high-voltage output of the capacitor energy storage device Sn, and the second The swarm electrode 15 of the second switch 7 is connected to the forming elements of the discharge circuit Lf, Rf.

To ensure an acceptable level of shielding, the distance h from the first electrode 9 of the switch with a glow discharge 7 to the edge of the glass should be at least two diameters of the glass.

Thus, the implementation of the claimed installation reduces the capacitive coupling Cn of the common electrode 12 with the elements of the discharge circuit, reduces the time of existence of the high-frequency interference signal to 1-2 μs and reduces by 30-50 times the magnitude of the high-frequency noise to a level equal to or slightly higher than the useful signal.

Installation work.

The operation of the proposed installation is illustrated by the schemes shown in figure 1 and figure 2. After supplying the control signal to the switch with a common electrode 11, a spark breakdown of the air gap between the electrodes 8 and 13 of the controlled spark gap 6 occurs, the capacity of the common electrode 12 is charged to a voltage equal to the charging voltage of the storage capacitor Sn for a time less than 0.1 μs . In this case, shock excitation of the circuits, including elements of the discharge circuit and the capacitance of the common electrode 12 occurs. discharge circuit ten times.

After the breakdown of the gap between the electrodes 8 and 13 of the switch 6 for a period of 1 to 10 μs, the gap between the electrodes 9 and 15 of the switch 7 smoothly transitions from a non-conducting state to a conducting state due to the excitation of a glow (Townsend) discharge. In this case, there is no shock excitation of the discharge circuit, and parasitic vibrations practically do not occur. This significantly attenuates the level of high-frequency noise 25 (see Fig. 8) in the discharge circuit 4.

As a result of control experiments, waveforms of voltages in the same circuit were obtained during tests at the facilities described in SAE ARP5416, in RF patent No. 44104, and in the claimed setup. A comparison of the ratios of noise levels and voltages induced in on-board circuits during tests on known and claimed installations shows the efficiency of the claimed installation, as illustrated in Figs. 7a, 7b and 8. The weakening of capacitive coupling due to changes in the design of the switches leads to a significant (30-50 times) reduction in the level of oscillations up to values not exceeding the level of the useful signal (see Fig. 8).

Thus, a decrease in the capacitive connections of the circuit section between the switches with the elements of the test circuit due to a decrease in the parasitic capacitance of the common electrode leads to a decrease in the amplitudes arising in the discharge circuit of high-frequency damped oscillations after the operation of the controlled spark gap by a factor of 30-50 time. The sections of the discharge circuit connected to the second electrode of the second switch do not excite high-frequency (wave) processes as a result of the delayed operation (ignition) of the additional switch that implements the Townsend discharge ignition mechanism.

Claims (2)

1. Installation for testing aircraft with lightning resistance, including a charger, measuring systems of the discharge circuits and the test object, a discharge circuit consisting of a series-connected shunt, a capacitor storage of energy, two switches, the first of which is a controlled spark gap, and the second switch triggered with a time delay relative to the start of switching on the controlled spark switch, the voltage of the second switch is not less than 0.2 of the voltage I controlled spark switch, forming elements, characterized in that the first electrode of the first switch and the first electrode of the second switch are interconnected by a conductor no more than 1-2 cm long, forming switches with a common electrode, the second electrode of the controlled spark gap and the common electrode are enclosed in a metal a screen made in the form of a glass with a bottom connected to the second electrode of the controlled spark gap and connected directly to the high-voltage output of the capacitor storage energy of Tell, and the second electrode of the second switch is connected to the discharge path forming member. 2. Installation for testing aircraft with lightning resistance according to claim 1, characterized in that the distance from the first electrode of the second switch to the edge of the glass should be at least two glass diameters.

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