Application of NGI modular instrument in transient disconnection test of automotive wiring harness system

The automotive wiring harness system is the main carrier connecting the battery and various electrical components, and it is a relatively weak and easily damaged part in the vehicle components. The reliability of the automotive wiring harness is directly related to the safety performance of the vehicle. In the test of the automotive wiring harness, in addition to the basic impedance, overload capacity and other parameter tests, there is another very important parameter, that is, the instantaneous disconnection parameter.
Instantaneous disconnection is an instantaneous circuit break, which refers to the instantaneous disconnection of the wiring harness due to temperature changes and vibration environments. This disconnection may be within microseconds, and this microsecond disconnection may sometimes be fatal to the automotive electronic system. Especially in emergency situations, due to the instantaneous disconnection of the communication harness, important communication data in the car computer is lost, causing the car to lose control. Since the instantaneous disconnection parameter is of great importance, how to measure the instantaneous disconnection parameter has also become a key issue for automobile manufacturers and automotive wiring harness manufacturers.

Based on the above needs, NGI has developed an automotive wiring harness instantaneous circuit break resistance system instrument (N8150A). The N8150A high-voltage electrical instantaneous circuit break resistance tester can be used as a monitoring instrument for wiring harness connectors and their components in a vibration test environment. High-precision, high-resolution sensitivity and amplitude detection design, synchronous detection of environmental variables such as acceleration and temperature, provide users with more references for analyzing instantaneous disconnection situations. It can meet the needs of connector and component (wiring harness) testing in application fields such as vehicles, home appliances, aviation, ships, and medical devices. N8150 complies with the global mainstream automotive industry instantaneous disconnection related test standards, with ultra-high connection resistance sampling accuracy and sampling rate of more than 10MSps.

N8150A has the following features:
Ø Powerful transient analysis software, which can display the transient waveform of any channel
Ø Time resolution: 0.1 uS
Ø Transient resistance resolution: 0.01 Ω
Ø Transient resistance measurement accuracy: 0.1%+0.1%F.S.
Ø Single machine supports 10 channels, and can support simultaneous testing of dozens of channels
Ø Powerful data storage and analysis functions
Ø 100M Ethernet communication

The biggest difficulty in measuring transient parameters is how to accurately and reliably detect microsecond-level disconnections. NGI uses a high-precision voltage source to energize the harness or connector and generate current, and then uses a high-speed, high-precision sampling circuit to sample the voltage of the high-side sampling resistor, and converts the impedance of the harness under test through the voltage divider ratio to achieve the purpose of real-time acquisition and monitoring of harness impedance.
A single machine supports 10 channels, and can support simultaneous testing of dozens of channels, which can save testing costs for customers to a large extent.
In addition to the transient measurement of the main channel, this set of equipment is also equipped with temperature sensors and vibration measurement sensors for auxiliary testing. The main measurement and control boards of the measuring equipment are all integrated in the NXI measurement and control chassis. At the same time, the entire test system greatly reduces external wiring, thereby reducing the complexity of the entire system. The entire system architecture is shown in the figure:

NGI's transient tester mainly consists of:
Ø NXI measurement and control chassis and boards
Ø Industrial control computer
Ø Environmental detection sensor
Ø Standard 19-inch mobile cabinet

After the NGI transient test system is delivered to customers, it can fully meet the needs of customers and can effectively help wire harness manufacturers identify the quality of wires. By setting the time width threshold and the transient resistance threshold to test whether the wire harness has a transient, counting the number of transients and recording the details of the impedance changes of the wire harness before and after the transient, it can meet the test standards in the automotive industry such as SAE-USCAR-2. The powerful host computer software can count and save the test data in real time, and the relevant data can be retrieved by users at any time. In addition, the N8150A transient tester has a self-calibration function. After the device is powered on, the user can use the host computer to perform self-calibration of the system to make the measurement results more accurate.