Harness Testing Application Note

General

This application note will give you some idea on how the Thermotron Product Test System (PTS) can be applied to your cable harness or connector assembly testing needs. This application is specifically for "Connector System Maximum Current" testing and "Current Cycle" life testing.

Modular design, flexibility, low cost, and the ability to run multiple tests on multiple products are some of the features that make the Thermotron PTS an excellent choice for this application. Refer to the applicable PTS Data sheets for detailed information in this application note.

Typical Cable Harness Product

A typical cable harness consists of a number of connectors or terminals with crimped or soldered wires attached. The test may be on 1) the termination of the wire to the connector or terminal, or 2) the test may be on the connector contacts of the mated pair.

General Testing Strategy

The Cable Harness Tester is designed to test for voltage drop across the connector or terminal pair at its maximum rated current. The tester will test 720 terminal pairs for a voltage drop. The terminal pairs are connected in series to provide a continuous loop at the rate current. The tester in this application note tests two loops at a time with 360 terminal pairs in each loop. This example shows how multiple PTS base units can be combined in a building block fashion to expand the number of products to be tested. Two duplicate configurations are used.

Providing Power

Two independent power supplies are used to provide programmable current sources from 0 to 8 amps. To control the power supplies, the Power Supply Programming Module (PSM-2) is utilized. The PSM-2 is capable of controlling two independent power supplies with resistance programming. A programmable current is supplied to the products under test through the PTS software. The power supply voltage and current are monitored by the use of an Analog Input Module (AIM-32) to verify correct operation.

Sensing Voltage Drop

The terminal pair voltage drop is sensed by the combined use of the Analog Input Module (AIM-32), and the Multiplex Module (MPX-32). The MPX-32 function module is a 128 channel to 32 channel Multiplexer. This expands the 32 channel of the AIM function module to 128. The tester utilizes six AIM and six MPX modules for a total channel capacity of 768. Some of the channels are used for diagnostics which reduces the tester capacity to 720 terminal pairs.

Load Boards

Load boards typically provide loads that a product expects to see under normal conditions. The load boards used in this application provide signal conditioning and buffering for the voltage drop sensing. Additionally, the load boards provide a method of interfacing the PTS function modules to the units under test. Minor modifications or changing a load board may be all that is required to modify a PTS tester for another product.

PTS Profiles

After the PTS equipment is set up, the PTS software must be configured for the particular application. The software is generic and has a standard interface that is consistent from one tester to another. This simplifies the training and use of the Thermotron testers. To configure the PTS software, profiles must be defined for the function modules used. No programming is required, but a clear understanding of the PTS configuration and the product test requirement is needed.

Physical Configuration

A 19 inch console is typically used for the PTS equipment mounting. The console is mounted on a caster base for mobility. The load boards are mounted on the top with the PTS base unit below them. The power supplies are mounted at the bottom. The connectors to the units under test are typically mounted on the back of the console. These are usually a circular panel mount connector to provide for a removable cable assembly to the product. Each product type can have its own cable assembly for quick change over.

Conclusions

As shown by the information presented in this application note, the PTS from Thermotron Industries provide an excellent method for testing harness assemblies at maximum current. This tester can be used with most of Thermotron’s environment simulation equipment with its built-in interface or can be used as a standalone tester. The advantages of the modular PTS testing method includes flexibility, low cost, and ease of implementation. Contact Thermotron to have your testing needs analyzed and solved.