Regarding soft switching
Thread Content
Hello, I would like to ask what a soft switch is. Currently, the owner of a project is asking us to add soft switches to the interlock circuits in the logical interlock diagram. I’m wondering what exactly that means.
A soft switch is a method and device used in electrical circuits to connect and disconnect loads. This approach involves the disconnection and connection of the load not being done abruptly in an instant, but rather gradually – with the connection process taking place slowly from a low level to a high level, and the disconnection process occurring slowly from a high level to a low level.
Based on my understanding of the owner’s requirements, it is necessary to add a \"bypass button\" in each interlock condition circuit. Its main purpose is to facilitate maintenance, allowing for easy temporary disactivation and reactivation when needed. Moreover, appropriate permissions and confirmation functions must be implemented for operating this \"bypass button\".
A soft switch is a switch within the system, typically occupying 1 bit of storage space； Unlike hard switching, it does not require hard wiring and does not consume actual I/O points. It is usually used to temporarily store intermediate calculation results or manually input parameters
In my actual work, I have encountered two types of bypass switches: one type involves adding a bypass switch in each interlock condition circuit, which allows those interlock conditions to be ignored for the purpose of simplifying maintenance. Another approach is to add a bypass switch, which together with the interlock conditions forms a logical expression that appears as an OR in the logic diagram. This bypass switch cannot be turned on directly; it is necessary to first turn on the main bypass switch. To do this, the corresponding password must be entered. Only after the main bypass switch is turned on can this bypass switch be activated. Both of these bypasses come with a confirmation function.