Cable tester scheme for wiring layout and testing of electric vehicle units

First, the application background

In recent years, with the rapid development of China’s high-speed rail industry, the demand for high-speed electric units has continued to flow. The design and production of electric power units is a complex production process, in which the layout and inspection of electrical circuits is an important part of its production. The electrical wiring layout of electric vehicles has many wiring harnesses, crossover of various circuits, and complex and diverse connectors and terminal blocks, which all bring difficulties to the conduction test of electrical circuits of electric vehicles. The traditional line conduction test relies on manual work, and the use of the signal for conduction test brings low work efficiency and is prone to human factors leading to construction quality problems. Take advantage of automatic

Cable tester

The conduction test of the electric vehicle unit line can greatly improve the degree of production automation and test accuracy.


Test system composition

The automatic cable test system is mainly composed of a host computer, a test host, a distributed slave, a power bus and a communication bus and an adapter cable. The upper computer performs program editing and download and communicates with the lower test host; The test master executes the program and communicates with the distributed slaves; Data acquisition of the interface between the slave and the vehicle under test cable connection through the adapter cable.

Third, the test principle

1. Line conduction test;


Automatic cable test system, according to the actual test vehicle cable situation edit the test program, through the transfer cable and adapter fixture, to the wire harness to be tested to apply a certain current, measure the voltage value and current value at the end of the cable, by the tester internal measurement results using Ohm’s law to convert to obtain an accurate resistance value, and then realize the test and inspection of the vehicle wiring harness and cable.

2. The working principle of the test system;

The harness tester excites the test cable, which can accurately test the on-resistance and conduction current of the cable to quantitatively analyze the overall connection condition of the cable. Further, the insulation inside the cable is analyzed by accurately measuring the leakage current between any two cores in the cable at different voltages. The correct cable connection topology is automatically generated by the self-learning function and documented as a test standard. Automatically compare measurement results with test standards, analyze cable connection conditions and give analysis reports.

The normal connection and common failures of the wiring harness are shown in the following figure:

Schematic diagram of the wire harness conduction test

In the figure, the rectangular box represents the harness connector, each group of two connectors has five connection points, different connection conditions will produce a corresponding matrix, and finally the type of fault and fault terminal can be judged by the value of the matrix.

3. Comparative test;


In the wire harness self-learning on test, the test results can be used as a standard and compared with the test after the start of the test function, and the test results are not displayed when the results obtained are consistent; When the test results are inconsistent, the test points are prominently marked to facilitate the user to receive the information in a timely manner. On-off test (single point), resistance test (single point), withstand voltage test (single point) test, insulation resistance test (single point), transient test (single point) completion results and comparative test results can save samples (the saving path can be selected by yourself, easy to view). And the test report can be generated from the tested information.

(1) Test report

The equipment can output a test report after each test, which can list the data of each test result in detail, and can be saved in PDF, WORD, EXCEL and other formats in the computer, U disk, or print out paper files through the printer as the basis for testing.

The test report consists of the following parts:

(2) Test parameters

Test parameters include test time, path to test file, operation function number, specific test parameters, and operation control instructions. The above test information is convenient for archiving and querying.

(3) Test information

Including conduction and on-off test, resistance test, withstand voltage test, insulation resistance test, transient test (customizable configuration) test results, pass or not, test address and corresponding pin number. The above information is the main basis for workers to judge whether the cable has a conduction fault.

IV. Summary

Through the application of automatic wiring harness tester in the conduction test of EMU cable, the advantages of manual testing are summarized as follows:


It can ensure that human error is eliminated and the test results are more reliable.


Insulation tests that cannot be performed by manual testing can be completed.


It saves a lot of testing time and improves work efficiency. Fast batch measurements can be achieved, and the efficiency is much greater than that of manual conduction testing.

Fourth, convenient and fast manual test module, self-learning function can quickly and conveniently locate fault types and locations. Fault location cannot be done by manual conduction.

Cable tester

Cable tester

Cable tester

Cable tester

Cable tester

Cable tester