TESTING APPARATUS FOR DETECTING INSULATION RESISTANCE OF A HIGH VOLTAGE LINE AND METHOD FOR SAME

Abstract

A testing apparatus and a method for detecting insulation resistance of an unshielded high voltage line are provided. The testing apparatus has a voltage source for providing a measurement voltage for the high voltage line, an accommodating device for accommodating the high voltage line and for connecting the high voltage line to the voltage source, an insulation tester for detecting the insulation resistance on the basis of the measurement of a leakage current via the insulating sheath, two electrically conductive half shells which, when combined, form hollow cylindrical sheathing for the high voltage line, and two contact probes which can be electrically connected to the sheathing and to an inner conductor of the high voltage line. The insulation tester is designed to measure a current between the contact probes as the leakage current.

Claims

1.-9. (canceled)

10. A testing apparatus for capturing an insulation resistance of an unshielded high-voltage line provided for connecting high-voltage components of a motor vehicle and having at least one electrical internal conductor and an insulation jacket surrounding the at least one internal conductor, the testing apparatus comprising: a voltage source that provides a measurement voltage for the high-voltage line; an accommodating device that accommodates the high-voltage line and connects the high-voltage line to the voltage source; an insulation tester that captures the insulation resistance on the basis of a measurement of a leakage current via the insulation jacket; two electrically conductive half-shells which, in an assembled state, form a sheath in the form of a hollow cylinder for the high-voltage line; and at least two probes which are electrically connected to the insulation tester, wherein a first probe is electrically connectable to the sheath and a second probe is electrically connectable to the at least one internal conductor, and the insulation tester is designed to measure a current between the first and second probes as the leakage current.

11. The testing apparatus according to claim 10, wherein the half-shells are in the form of copper sheets.

12. The testing apparatus according to claim 10, wherein a length of the half-shells and, therefore, a length of the sheath, is adaptable to a length of the high-voltage line by virtue of the half-shells having a reversibly variable length.

13. The testing apparatus according to claim 12, wherein the half-shells are configured to be extendable in a telescopic manner.

14. The testing apparatus according to claim 10, wherein the accommodating device has two adapters which are electrically connectable to the voltage source, wherein a first adapter is electrically connectable to a first end of the high-voltage line, and a second adapter is electrically connectable to a second end of the high-voltage line.

15. The testing apparatus according to claim 10, further comprising: a guide system by which the half-shells are mounted in a slidable manner with respect to the accommodating device and, in order to arrange the half-shells on the high-voltage line, are pushed together with the formation of the sheath.

16. The testing apparatus according to claim 15, wherein the guide system has, for each half-shell, at least one guide with two sliding rods in each case and a connecting web arranged between the two sliding rods, a respective half-shell is fastened to the connecting web, and the connecting web is mounted in a linearly displaceable manner on the two sliding rods via guide elements.

17. The testing apparatus according to claim 10, further comprising: at least one filling element which is arrangeable on the high-voltage line, wherein when an external diameter of the high-voltage line is less than an internal diameter of the sheath formed by the half-shells, whereby a cavity is formed between the high-voltage line and the sheath, the filling element is arranged in the cavity in order to fix the high-voltage line in the sheath.

18. The testing apparatus according to claim 17, wherein the at least one filling element is in the form of a bending ring formed from an elastic material.

19. A method for testing a high-voltage line via a testing apparatus for capturing an insulation resistance of the high-voltage line which is provided for connecting high-voltage components of a motor vehicle and has at least one electrical internal conductor and an insulation jacket surrounding the at least one internal conductor, wherein the testing apparatus comprises: a voltage source that provides a measurement voltage for the high-voltage line; an accommodating device that accommodates the high-voltage line and connects the high-voltage line to the voltage source; an insulation tester that captures the insulation resistance on the basis of a measurement of a leakage current via the insulation jacket; two electrically conductive half-shells which, in an assembled state, form a sheath in the form of a hollow cylinder for the high-voltage line; and at least two probes which are electrically connected to the insulation tester, wherein a first probe is electrically connectable to the sheath and a second probe is electrically connectable to the at least one internal conductor, and the insulation tester is designed to measure a current between the first and second probes as the leakage current, the method comprising the steps of: arranging the high-voltage line in the accommodating device; using the half-shells to sheath the high-voltage line; connecting the two probes to the at least one electrical internal conductor and to the sheath; applying the measurement voltage to the high-voltage line by connecting the accommodating device to the voltage source; measuring the current between the two probes; and determining the insulation resistance from the current between the two probes and the measurement voltage provided by the voltage source.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is a schematic illustration of an embodiment of a testing apparatus according to the invention.

[0022] FIG. 2 is a cross-sectional illustration of high-voltage lines which are tested using the testing apparatus.

[0023] FIG. 3 is a schematic illustration of a sheath for a high-voltage line.

[0024] FIG. 4 is an illustration of a profile of the insulation resistance against time.

[0025] FIG. 5 is an illustration of profiles of the insulation resistance against the measurement voltage.

[0026] FIG. 6 is a schematic illustration of a guide system of the testing apparatus.

[0027] FIG. 7 shows a cross-sectional illustration of a high-voltage line.

[0028] In the figures, identical and functionally identical elements are provided with the same reference signs.

DETAILED DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 shows a testing apparatus 1 for a high-voltage line 2 which is provided for the purpose of electrically connecting high-voltage components of an electrically drivable motor vehicle. As shown on the basis of the cross-sectional illustration in FIG. 2, the high-voltage line 2 is unshielded and has precisely one internal conductor L1 (one-conductor system A in FIG. 2) or a plurality of internal conductors L1, L2 (two-conductor system B in FIG. 2). The internal conductor(s) L1, L2 is/are surrounded by an insulation jacket 3 made of an electrically insulating material. The testing apparatus 1 is designed to check an insulation resistance of the insulation jacket 3. For this purpose, the testing apparatus 1 has a voltage source 4 which is designed to provide a measurement voltage for the high-voltage line 2. The high-voltage line 2 is arranged in an accommodating device 5 of the testing apparatus 1, which accommodating device has two adapters 6 for making electrical contact with the high-voltage line 2. The accommodating device 5 can be connected to the voltage source 4 via a controllable switch S. When the switch S is closed, the measurement voltage provided by the voltage source 4 is applied to the high-voltage line 2. The testing apparatus 1 also has an insulation tester 7 which is designed to measure a leakage current via the insulation jacket 3 and to determine the insulation resistance of the insulation jacket 3 on the basis of the leakage current and the measurement voltage.

[0030] Since the high-voltage line 2 is unshielded and does not have an electrically conductive shield which can be used as a reference potential and with respect to which the internal conductor L1, L2 can be tested, the testing apparatus 1 has two half-shells HS1, HS2 which are formed from an electrically conductive material. For example, the half-shells HS1, HS2 may be in the form of copper sheets. The half-shell HS1 is, for example, in the form of an upper half-shell which is arranged on the high-voltage line 2 from above and can sheath an upper half of the high-voltage line 2 along its length. The half-shell HS2 is, for example, in the form of a lower half-shell which is arranged on the high-voltage line 2 from below and can sheath a lower half of the high-voltage line 2 along its length. In the assembled state, as shown in FIG. 3, the half-shells HS1, HS2 form a sheath 8 in the form of a hollow cylinder or a tubular sheath 8. The missing shield of the high-voltage line 2 can be “simulated” by the sheath 8. The sheath 8 can be connected to a reference potential, for example ground M, via the accommodating device 5, for example.

[0031] In order to measure the leakage current, when the switch S is closed, a current flowing between the at least one internal conductor L1, L2 and the sheath 8 is measured. For this purpose, the testing apparatus 1 has at least two probes T1, T2, T3. A first probe T1 is connected to the sheath 8. A second probe T2 is connected to the internal conductor L1. In the case of the two-conductor system B, a third probe T3 is additionally connected to the internal conductor L2. The probes T1, T2, T3 are connected to the insulation tester 7 which measures the current between the probes T1, T2, T3 and therefore between the respective internal conductor L1, L2 and the sheath 8. The insulation tester 7 may output a profile V1 of the insulation resistance R against time t, as shown in the characteristic curve according to FIG. 4. For example, the insulation resistance R can be captured after a particular period t1, for example 60 s, for a particular measurement voltage U=U1, for example 100 V. The measurement is then repeated for further measurement voltages U2, U3, etc. and a profile V2, V3 of the insulation resistance R against the measurement voltage U is determined. The profiles V2, V3 are shown in FIG. 5. The profile V2, in which the insulation resistance R is approximately constant for different measurement voltages U1, U2, U3 and exceeds a predetermined threshold value, characterizes an intact insulation jacket 3. The profile V3, in which the insulation resistance R decreases with increasing measurement voltages U1, U2, U3 and falls below the predetermined threshold value, characterizes a damaged insulation jacket 3.

[0032] FIG. 6 shows guide devices 9 of a guide system 10 of the testing apparatus 1, by means of which the half-shells HS1, HS2 are held and are mounted in a slidable manner with respect to the accommodating device 5. The guide devices 9 each have two sliding rods 11, 12 which are fastened to the accommodating device 5 in a stationary manner. A connecting web 13, to which the half-shells HS1, HS2 are fastened, is respectively arranged between the two sliding rods 11, 12. The connecting webs 13 are connected to the sliding rods 11, 12 via guide elements 14, for example guide rings, and can therefore be pushed up and down. In order to arrange the half-shells HS1, HS2 on the high-voltage line 2, the connecting web 13, to which the upper half-shell HS1 is fastened, is pushed down and the connecting web 13, to which the lower half-shell HS2 is fastened, is pushed up. The half-shells HS1, HS2 are pushed together as a result and are placed flush against one another. In this case, the high-voltage line 2 is enclosed between the half-shells HS1, HS2. For example, one of the half-shells HS1, HS2, here the lower half-shell HS2, may have a receptacle 16 in which the other half-shell HS1, here the upper half-shell HS1, is accommodated and is held on the lower half-shell HS2 in a stationary manner.

[0033] If an external diameter D1 of the high-voltage line 2 is less than an internal diameter D2 of the sheath 8, a filling element 15 can be arranged between the high-voltage line 2 and the sheath 8, as shown in FIG. 7, and holds the high-voltage line 2 in the sheath 8. The filling element 15 may be a slotted rubber ring, for example.

LIST OF REFERENCE SIGNS

[0034] 1 Testing apparatus

[0035] 2 High-voltage line

[0036] 3 Insulation jacket

[0037] 4 Voltage source

[0038] 5 Accommodating device

[0039] 6 Adapter

[0040] 7 Insulation tester

[0041] 8 Sheath

[0042] 9 Guide devices

[0043] 10 Guide system

[0044] 11, 12 Sliding rods

[0045] 13 Connecting webs

[0046] 14 Guide rings

[0047] 15 Filling element

[0048] 16 Receptacle

[0049] L1, L2 Internal conductor

[0050] T1, T2, T3 Probes

[0051] HS1, HS2 Half-shells

[0052] S Switch

[0053] A One-conductor system

[0054] B Two-conductor system

[0055] U, U1, U2, U3 Measurement voltage

[0056] R Insulation resistance

[0057] V1, V2, V3 Profiles

[0058] t, t1 Time

[0059] D1, D2 Diameter

[0060] M Ground