Although the contacts are in contact, the armature is still not fully attracted (with gaps) by the iron core. Of course, this is not the working pressure value. (Incomplete action) "The sound is very low (click)" (Figure 1)
2.Full action (= motion voltage)
Continue to increase the voltage after the contact is made, the voltage when the armature is completely attracted by the iron core.
"The sound is loud (click)! ! " (figure 2)
Secondary action: The relay action performed in the order of 1) and 2) above is a secondary action.
Direct voltage: Instead of gradually increasing the voltage, directly input the preset voltage.