TEMPERATURE RISE TESTING FOR CABLE CONNECTORS

TEMPERATURE RISE TESTING FOR CABLE CONNECTORS

Customers continue to raise the bar for cable assembly manufacturers who must continuously innovate new products to meet increasingly demanding applications. For example, in automotive applications, wiring in the engine compartment can easily reach temperatures over 195 degrees. When it comes to high-temperature applications, all cable and connector components must be carefully evaluated via temperature rise testing.

When evaluating the heat threshold for cable and connector assemblies, it’s important to consider the environment in which the product will operate, as well as the minimum and maximum potential temperature required for the cable and connector to operate safely without disruption to power or signal, and without external or internal damage. Several cable design elements will impact how a product performs in higher temperature settings, including:

· Ampacity

· Cable insulation used to isolate the contacts/terminals

· Overmolding material around the cable

· Mechanical hardware components

· Sealing elements

Ampacity

Ampacity is an electrical rating system that defines the maximum current of energy a conductor can carry without exceeding its temperature rating. As you can imagine, this design detail is imperative to the safety and success of any cable and connector assembly. Ampacity guidelines are regulated by the National Electric Code (NEC) and can vary greatly depending on exposure to ambient temperature. If miscalculated, wires can overheat, causing irreversible damage to cable conductors and insulation. In severe cases, overheating can even result in fires, explosions and serious injury.

Temperature Rise Testing

Gauging the temperature performance of a cable assembly is done using a temperature rise test. This test is governed by UL 310, which states that the maximum current carrying capacity of a connector (aka, ampacity) is based on the current that causes the connector body temperature to rise by 30 degrees from its natural state. To perform this test, engineers set up a controlled environment and utilize several pieces of testing equipment, including:

· Power supply

· Electronic load

· Thermocouples

· Holding fixture

· Vented test enclosure

· Monitoring software

To begin, the thermocouples are attached to the device under test. Next, a skilled technician supplies the cable and connector assembly with power and electronic load. The thermocouple sensors read the assembly’s temperature and communicate information to specialized software, which creates a line graph to illustrate temperature thresholds. The goal is to monitor the assembly until it increases by 30 degrees.

After the test is conducted, engineers assess the results, which come in the form of two curved lines. The first indicates the standard operating current for the cable and connector assembly, which takes into account external factors, such as manufacturing variations and temp testing errors. The second indicates the maximum operating temperature.