RU2334335C2 - System of distribution of electric power - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: system contains a power unit, connected to its output lines of the switchboards of circuits of the feed circuits of instruments and the control unit of the switchboards, the additional switchboards, connected to the output lines of the power unit, which through the first and second resistors with identical ratings are connected with the first input of the control-measuring equipment and on the case ("ground") of the article, and through the third and fourth resistors with identical ratings - with the second input of control-measuring equipment, the simulator of insulation resistance of the inputs is connected to the outputs of additional switchboards, and by a common point is connected to the case ("ground") of the article, thus the simulator is executed in the form of additional resistors whose first outputs are connected to its inputs, and the second outputs are connected to its common point.

EFFECT: increase in the operational reliability of the distribution system of electric power by guaranteeing of reliable control of insulation resistance of the system and the equipment fed by it.

2 cl, 2 dwg

Description

The invention relates to the field of electrical engineering and can be used in power distribution systems, for example, as part of an airplane, ship or spacecraft (SC).

Electric power distribution systems in spacecraft equipment are usually performed using power buses that are completely isolated from the body of the product, for example, [1]. Other spacecraft equipment is also isolated from the hull in terms of primary power distribution circuits. With this construction of the power distribution system, a short circuit to the chassis of any power bus or any circuit inside the powered devices does not lead to emergency situations, in contrast to when one of the power buses is connected to the product’s chassis (“grounded”) normally, and in the second circuit power bus defect appears. In this case, a complete discharge of on-board power sources such as batteries or a fire hazard is possible. Monitoring the insulation of power buses from the body (“ground”) of the product during operation is one of the measures to ensure the reliability of various power distribution systems and spacecraft control systems as a whole over a given service life.

A known power distribution system [2], comprising a power supply unit, switchboards for power supply lines of devices connected to its output buses, and a control unit for power supply line switches (input control bus).

However, as in any power distribution system, insulation deteriorates during operation, with time, even a breakdown of insulation on the case is possible, especially in circuits and devices in outer space under the influence of radiation from outer space or as part of inhabited compartments from exposure aggressive components of the atmosphere. In case of violation of isolation, information exchange deteriorates, the likelihood of false power-ups of the equipment, non-execution or formation of unauthorized commands, etc. increases. Detection of the fact of isolation violation allows timely shutdown of suspicious equipment or switch to backup control channels.

To control the insulation resistance of the power buses, in conjunction with the power supply circuits of the spacecraft instruments connected to them, control equipment is used that connects the system power buses alternately through the reference circuit to the product body and monitors the voltage on the tires relative to the product body and the currents flowing through this circuit. An analogue made by this principle can be illustrated by an example of a technical solution from the description of the patent [3].

However, in a power distribution system with a pulse interrogation of the insulation resistance on the body ("ground") of the product, interference and electromagnetic incompatibility of some devices occur. Therefore, such a check of the power distribution system can only be used for ground testing of the product, and then not in all operating modes, and in flight it cannot be used at all, especially for continuous monitoring of the insulation state. At the same time, monitoring the insulation resistance (leakage currents) in the power distribution system and in the powered equipment and its reliability can help take preventive measures to prevent abnormal situations on board during the long-term operation of the spacecraft.

It should be specially noted that monitoring the insulation resistance in the continuous mode also has drawbacks, in particular, if the device for checking the insulation resistance of the power buses relative to the spacecraft’s body failed, or its metrological characteristics changed significantly, then its readings may indicate a good insulation relative to the case, even if any power bus is shorted to the product case, or gives false information about leaks on the case in the power circuits. It is clear that this situation reduces the reliability of the control.

As the closest analogue to the proposed system, the aforementioned device [2] is considered containing the maximum number of features of this power distribution system, namely a power supply unit, switchboards for power supply circuits connected to its output buses and a control unit for controllers switchboard power supply circuits.

The objective of the proposal is to increase the operational reliability of the power distribution system by ensuring the reliability of monitoring the insulation resistance of the power distribution system and the equipment it feeds, which will ensure timely transition to the reserve in case of detection of an unacceptable decrease in insulation resistance.

This problem is solved by the fact that four resistors, a control and measuring device, additional switches connected to the output buses of the power supply unit are introduced into the power distribution system containing the power supply unit, the switchboards for the instrument power supply circuits and the control unit for the switchboard for the instrument power circuits , and a simulator of insulation resistance, moreover, the buses of the power supply unit are connected through the first and second resistors to the first input of the measuring instrument and the housing ("ground") of the product, and Without the third and fourth resistors connected to the second input of the measuring instrument, the insulation resistance simulator is connected to the outputs of additional switches, and the common point is connected to the body ("ground") of the product, while the insulation resistance simulator is made in the form of reference resistors, the first conclusions which are connected to the inputs of the simulator of insulation resistance, and the second conclusions are connected to its common point. In addition, the first and second resistors of the power distribution system can be made with the possibility of their simultaneous change, for example, using the signals of the measuring instrument.

Figure 1 shows a block diagram of the proposed power distribution system,

where are indicated:

1 - power supply;

2 - control unit;

3, 4 - devices;

5 - instrumentation;

6 - simulator of insulation resistance;

7, 8, 9 and 10 - power supply circuits of devices;

11, 12 - resistance of devices 3, 4 (usually low-impedance and complex);

13, 14 - insulation resistance of power buses;

15, 16, 17, 18 - insulation resistance of power circuits of devices 3.

On the power supply unit 1, the signs “+” and “-” indicate the power supply system distribution busbars, E - the output voltage of the power supply 1;

K1, K2, K3, K4 - switches of devices power circuits (relay and / or electronic);

K5, K6 - additional switches;

R1-R4 - resistors;

R5, R6 - reference resistors.

Figure 2 shows as an example an embodiment of resistors R1 and R2 with a possible change in their resistance using the switch SA and resistors R7, R9, R8 and R10.

A power distribution system (Fig. 1) is implemented as follows.

The output buses “+” and “-” of the power supply unit 1 with voltage E are connected to the control unit 2 and to the inputs of the switches K1, K2, K3, K4, K5, K6, to the outputs of which the corresponding devices 3, 4 of the spacecraft’s onboard equipment are connected, and also a simulator of insulation resistance 6. The control unit 2 controls all switches (shown by arrows). Such a construction of the power distribution system provides bipolar switching of the power supply circuits 7, 8, 9 and 10 of devices 3, 4 and the insulation resistance simulator 6. The “+” and “-” buses of the power supply unit 1 are connected through the resistors R1 and R2 with the same ratings ( "Ground") products. One input of the measuring instrument 5 (left according to the diagram) is also connected to the body ("ground") of the product, the second input of the measuring instrument 5 through resistors R3 and R4 with the same ratings (not necessarily equal to the values of the resistors R1 and R2) is also connected with power distribution system power buses. Switches K1-K4, as well as K5 and K6, can be made both on the relay contacts, and on field-effect transistors. The drawing shows both options. The purpose, types, number of devices 3, 4 and their resistance 11, 12 are not fundamental. The insulation resistance simulator 6 consists of reference resistors (Fig. 1 shows two resistors R5 and R6, if necessary, there can be more with a corresponding increase in the number of simulator inputs leakage resistance), the first conclusions connected to the inputs of the simulator of insulation resistance, and the second - to its common point. The simulator resistors must imitate a certain maximum insulation resistance in order to check the operability and sensitivity of the measuring instrument 5, if necessary at different measurement ranges, if it is a multi-limit, minimum permissible insulation resistance, in order to check the operability of the spacecraft equipment involved at this stage.

The resistors 13, 14, 15 and 16, 17 and 18, shown by the dotted line in FIG. 1, are respectively the insulation resistances of the power buses of the power distribution system as a whole and the power supply circuits of devices 3, 4. In this case, a decrease in insulation resistance can occur both inside the devices ( insulation resistances are shown in the device 3) and beyond (as shown for device 4).

Figure 2 shows an example of the execution of resistors R1 and R2 with a possible change in their values using the switch SA and resistors R7, R9, R8 and R10 due to the commands of the measuring instrument 5. Changing the values of the resistors can also be performed using external commands or manually.

The power distribution system shown in FIG. 1 operates as follows.

Even before the power supply is turned on, resistors R1 and R2 ensure that charges are drained from the power buses. This eliminates the formation of high potentials on them and the possibility of electrical breakdown of insulation.

After turning on the power supply 1, the power distribution system of the on-board equipment of the product immediately gets under control in terms of isolation of the power circuits relative to the body ("ground") of the product. In this case, the same values of the resistors R1 and R2 form a grounded midpoint: the busbars of the power supply 1 take potentials relative to the body ("ground") of the product, equal to half the supply voltage E, namely + E / 2 - on the bus "+" and -Е / 2 - on the bus "-". Resistors R3 and R4 form their independent midpoint, the "floating" potential of which relative to the body ("ground") of the product is also equal to zero due to the equality of the nominal values of these resistances. At the same time, it is assumed that the power buses do not have a leak to the case or the actual leakage to the case ("ground") is negligible (the resistances 13 and 14 have values much greater than the resistances of the resistors R1 and R2). In this case, the control device 5, properly calibrated, shows zero leakage current or infinite insulation resistance (the bridge formed by the resistors R1-R4 is balanced). When a leakage current appears from one of the supply lines to the chassis (ground) of the product, for example, when the insulation resistance 13 decreases, up to a short circuit due to breakdown or damage to the insulation, the R1-R4 bridge is unbalanced due to that the insulation resistance 13 shunts the resistance R1, thereby reducing the potential of the “+” bus relative to the chassis (up to zero volts during a short circuit). Due to the imbalance of the bridge, the measuring instrument 5, having a scale with a midpoint, detects a decrease in insulation resistance precisely from the “+” bus to the body (“ground”) of the product. The control device 5, equipped with a threshold device, with a certain insulation resistance can give a light or sound signal - a warning about its unacceptable reduction, transmit this information via communication channels to the ground, etc. The specific design, composition, electrical circuit of the measuring instrument 5 are not included in the scope of claims, therefore, the materials of this application are not considered in detail.

Before the onboard devices 3, 4 are turned on, their insulation resistance 15 and 16, 17 and 18 of the power supply circuits are not accessible for monitoring, since the switches of these devices are turned off. At the same time, control of these resistances can be carried out in the "background mode" without turning the device on in the operating mode. To do this, using the control unit 2, it is enough to turn on only one switch, for example, switch K1, when checking the insulation resistance of device 3. Since the insulation resistance 15 and 16 are connected in parallel to the resistor R1, it is possible to determine the equivalent value of these values by changing the readings of the measuring instrument 5 resistances. Including the switch K2 instead of K1, according to the testimony 5, you can obtain confirmation of previous results or obtain additional information. With the standard inclusion of any device 3, 4, a decrease in the insulation resistance will lead to an unbalance of the bridge, and according to the testimony of the measuring and measuring device 5, the power bus with which the leakage current to the case ("ground") of the product appears.

During ground-based tests of the power distribution system and spacecraft equipment, the identification of insulation deterioration on the body ("ground") of a product requires taking measures to detect and eliminate the defect. During normal operation of the spacecraft, the occurrence of such a defect should be recorded by the measuring instrument 5, transmitted through its interface to the information collection and processing system (not shown in the drawing, since it is not included in the scope of the claims of this invention), and transmitted to the monitoring the measuring point (or the flight control center), here is analyzed with a “reference” to the situation on board the spacecraft according to other telemetry information received at the same time from other devices, and measures have been taken. Situations of insulation deterioration in the power distribution systems of spacecraft equipment most often occur “suddenly” when the devices are turned on or when they form some output commands. In this case, the analysis of the malfunction is significantly facilitated, since the moment of occurrence of the defect is “connected” in time with certain operations on the product, and the circuits involved in the occurrence of the defect can be immediately localized.

The signal at the output of the measuring instrument 5 in the simplest case indicates whether the insulation resistance to the body ("ground") of the product is normal or not. However, over a long spacecraft life, a change in insulation resistance (its degradation) occurs gradually, but steadily. In this case, the change in insulation resistance occurs "at times" and even by orders of magnitude, for example, in open space - from exposure to cosmic radiation, and in inhabited compartments - from various active components in the atmosphere of the compartments. In real conditions, the insulation resistance varies from tens to hundreds of megohms to units of kOhm, so the concept of “norm” in terms of insulation resistance undergoes changes over time.

To expand the range of measurement of insulation resistances, the resistances of the resistors R1 and R2 should have several values, for example, 10, 100 and 1000 kOhm (figure 2). Simultaneous switching of the values of these resistors (automatically by the same control device 5 by an external command or manually; at the same time, switching the values of the resistors R3 and R4 is practically not required) allows you to expand the range of measurement of insulation resistances, which, in turn, will make it possible to trace insulation degradation ( order from 100 MΩ to tens of Ohms), will help to predict the consequences of this degradation and take the necessary measures to neutralize it. Moreover, this solution allows you to perform long-term experiments on the quantitative measurement of changes in the insulation resistance of various new insulation materials in flight conditions. However, it should be borne in mind that in order to achieve high accuracy in measuring the insulation resistance, the control and measuring device 5 must be periodically subjected to metrological verification or adjustment. This is required even when its accuracy is not in doubt. And this is due to the fact that the bridge of resistors R1-R4 is connected directly to the output buses of the power supply, the supply voltage E of which in practice has significant deviations from the nominal value, which will inevitably lead to a change in the readings of the measuring instrument 5 in proportion to the change in the supply voltage E at a constant insulation resistance. In this case, using the control unit 2, you can turn on the K5 or Kb switch, connect one of the reference resistors R5 or R6 of the insulation resistance simulator 6 to one of the power buses and, by the difference in the readings of the measuring instrument 5, before and after connecting the reference resistor even without knowledge the current value of voltage E, you can adjust its readings. Such operations will confirm the accuracy of the test instrument 5.

As for the impulse noise affecting the electromagnetic compatibility of some devices, they are completely excluded in the proposed system, in contrast to the existing power distribution system equipped with a pulse device for controlling insulation, in which impulse noise is unavoidable during its operation.

A set of features, similar to that considered in this proposal, has not been met before to solve the problem and does not follow explicitly from the prior art, which allows us to conclude that the technical solution meets the criteria of "novelty" and "inventive step".

The invention is intended to be used on enterprise products as part of power distribution systems.

Currently, the proposed concept of building a power distribution system with insulation control on the body ("ground") of the product is being considered for inclusion in the terms of reference.

References

1. Pinigin N.Ya., Boldyrev V.I. DC power distribution system from common source buses. RF patent No. 2201645, H02J 1/00.

2. Ledenev G.Ya., Fedosov A.A. Multichannel voltage switch. RF patent No. 2214041, Н03К 17/08.

3. Borodyansky M.E., Borodyansky I.M. A method of measuring electrical insulation resistance. RF patent No. 2200329, G01R 27/16.

Claims (2)

1. An electric power distribution system comprising a power supply unit, switchboards for power supply circuits connected to its output buses and a control unit for switchboard power supply circuits for devices, characterized in that four resistors, a control and measuring device, additional switches connected to the output buses of the unit are introduced into it power supply, and a simulator of insulation resistance, and the output buses of the power supply, through the first and second resistors with the same ratings, are connected to the first input of the measuring instrument and the case ("ground") of the product, and through the third and fourth resistors with the same ratings are connected to the second input of the measuring instrument, the insulation resistance simulator is connected to the outputs of the additional switches, and the common point is connected to the case ("ground") of the product, wherein the insulation resistance simulator is made in the form of additional resistors, the first conclusions of which are connected to its inputs, and the second conclusions are connected to a common point of the insulation resistance simulator. 2. The power distribution system according to claim 1, characterized in that the first and second resistors are configured to simultaneously change them, for example, using the signals of the control instrument.

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