Do the motor’s operation signal and stop signal repeat?
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When specifying the electrical control interlock conditions, there are two options in the table: “Operation signal” and “Stop signal”. A running signal is definitely necessary. We usually don’t choose the stop signal, but when should we select this option? As I understand it, the signal lights turn off when the vehicle is parked, which indicates that it has come to a stop. Then isn’t this “stop signal” option redundant?
The stop signal can also indicate whether the circuit is powered. . .
For example, if the pump for the circulating water stops, the device’s protection system activates in accordance with the interlock scheme； When the exhaust fan stops, the furnace enters the interlock procedure. These relate to safety protection; the reason is that the equipment has stopped operating, and in principle, the signal corresponding to \"stoppage\" is used.
The presence of a \"running\" signal generally indicates the operating status of the equipment, but the absence of such a signal does not necessarily mean it is in a \"stopped\" state; for example, there may be a fault in the circuit that generates the \"running\" signal. Therefore, an independent “stop” signal is used for reliability; if it is simply the inverse of “run,” it may lead to incorrect operations. This is my personal understanding; please feel free to correct me.
When electrical interlock conditions are required, the stop signal can be selected. The operation signal indicates the operating status of the device and is not involved in interlocking.
It is difficult to express logic using a single signal in a flowchart.