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 Verfasst am: 06. Jun 2023 09:04 Titel: What are the top five performance needs for HVAC/harsh envir |
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What are the top five performance needs for HVAC/harsh environment connectors?
Amid a plethora of performance requirements for connectors used in heating ventilation and air conditioning (HVAC) systems and other harsh environments, five stand out as especially important — ingress protection against dust and moisture (IP rating), extreme temperature operation, balancing mating/unmating forces and contact resistance, retention force and locking mechanisms for robust operation, and safety.Get more news about Harsh Environment Connector,you can vist our website!
IP ratings
The IP classification system is defined in IEC 60529. Connectors in HVAC and harsh environments often need a high IP rating. IP ratings consist of two digits. The first digit indicates the level of dust and object protection on a scale from 0 to 6. The second relates to the level of protection against liquids (Figure 1). For example, a connector with an IP68 rating is dust tight and can withstand powerful water jets directed at it.
When specifying an IP rating, it’s necessary to consider how much exposure the connector will have to debris, tools, even fingers, and dust including very fine powdery particles, dirt, or sand, and whether the anticipated exposure is intermittent or continuous. Exposure to water is a major consideration for systems like HVAC that may be outdoors and exposed to the elements. IP ratings extend to systems that may be submerged.
Some HVAC systems and equipment used in harsh environments may require sealed connectors with an IP68 rating. That can include wire-to-wire connectors and other interconnect styles (Figure 2). If connectors are not properly sealed, dust, water, and other materials can get inside the connector, and potentially inside the equipment, disrupt signals, corrode contacts, and cause physical damage to other system elements.
Connectors are thermally rugged components. But they have temperature limits. Many connectors are rated for operation up to 85 C°. In the case of HVAC and other harsh environments like industrial and automotive systems, that’s often not sufficient. An HVAC condenser system, for example, may be located on the sunny side of a building in a hot climate where temperatures may be excessive. In addition, the motor drive and other electronics in the compressor will dissipate heat, pushing the temperature higher. And the contacts in power connectors carrying high currents can experience some level of self-heating.
Connectors designed for use in HVAC and harsh environments are often rated for 105 C° or higher. It can also be important to make sure the connector can function reliably in unusually cold weather. That same compressor that experiences summer heat, may be exposed to sub-zero temperatures in the winter.
Contact resistance can vary depending on the normal force between the pin and socket. A high contact normal force results in the greatest surface area contact between the pin and socket and lower contact resistance. Designs with low normal forces can result in inefficient signal or power transfer. Connectors are designed to balance the highest practical normal force with a reasonable level of required mating force. Mating and unmating involve different combinations of forces, as a result, mating requires greater force than unmating. During mating, the contacts are first spread open as the pins and sockets come together. The force required during this phase is a combination of the insertion (spreading) force and friction (Figure 3). During unmating, the contacts naturally return to the original shape without requiring any force and the only force experienced is friction.
Retention force is not the same as unmating force. Unmating refers to disconnecting a connector. There are two definitions of retention force. One definition relates to how firmly the pins are held in the connector body. Adequate contact retention force is needed to absorb contact mating forces and resist forces resulting from normal use of the connector. Retention force is measured in Newtons, and the correct retention force reduces the potential for contact damage. EIA-364 MIL-DTL-38999 Method 4.6.32 defines the axial force necessary to displace a contact from the proper location when inserted into a connector. Manual and automated tools are available for measuring retention force (Figure 4). |
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