switch design requirements and selection
Switch is the main interface for device power supply, relay start, function selection or a variety of man-machine interface. Depending on the application, the switch may not be visible and may not be directly sensed. Yueshi has been unremittingly pursuing innovation and quality of switching solutions in appearance, touch, performance and even sound. Our ultimate goal is for the user to always have a good switch experience in terms of feel, look, performance and effect.
When a switch is selected and assured that it performs its intended function, several important engineering characteristics must be evaluated. The most important of these constraints is the electrical performance level. The evaluation criteria for switches include rated current, rated voltage and contact resistance. These ratings are specified by the switch manufacturer and are determined by factors such as contact size, contact material and contact spacing. Electroplating erosion that may lead to premature high contact resistance is another factor that must be considered. Switch current rating is the maximum current the switch is designed to carry. Do not exceed rated current, otherwise it may not be possible to disconnect the circuit.
The rated voltage of the switch is the maximum voltage allowed in the circuit used by the switch. The rated voltage may be AC, DC, or both. If a switch is applied with a voltage greater than its rated voltage, the voltage may "skip" the break contacts of the switch, making it impossible to use the circuit to control the switch. In the case of the same current, the increase of voltage will cause more damage to the contacts and shorten the service life of the switch. Contact ratings range from a few milliamps to 6A and are available in multiple knife, multiple throw types and various configurations.
For design engineers, each harsh environment presents a unique set of challenges due to a variety of factors, such as extreme temperatures, water, chemicals, dust, grease, and other types of contaminants. A major feature of heavy equipment environments is the certainty of prolonged or particularly significant exposure to contaminants. These conditions also tend to produce temperature and vibration problems that may affect switch fit and performance.
Construction, mining and agricultural sites are not the most friendly environments for electrical components. When selecting switches for heavy equipment in the cockpit, using products that are not specifically designed for harsh environmental conditions can lead to a significant reduction in switch life expectancy or even serious switch failure.
Therefore, IP class switches are the best choice for heavy equipment applications. Based on the hierarchical classification system, IP class switches must be able to resist certain environmental factors. IP codes are part of the INTERNATIONAL Organization for Standardization (ISO) IEC60529 standard. The first digit of the IP code indicates the level of protection of the enclosure against contact with hazardous components (such as electrical conductors, moving parts) and entry of solid foreign objects. The second number is for liquids.
When engineers select switches, they shall not only conform to size and performance parameters, but also be user-friendly. Operators of heavy machinery are not necessarily Native English speakers, so shell symbols are important, as is the ability to customize those symbols. Again, these switches can be easily operated with one hand and are robust enough to withstand the repeated operations associated with typical functions.
Light switches are commonly used in applications with low light lines (such as dimly lit vehicle cabs) where it is difficult to identify switch functions, while backlit shell graphics provide highly visible indications to operators of which functions they have enabled. They also provide obvious feedback, which can be sensed through thick work gloves.
