1、Differentiation of terminal color
push button switch some from the color of the terminals can go to distinguish, this is to avoid operating errors, - generally will be made of different colors button cap, green (or blue) for normally open contacts, red (or pink) is normally closed contacts.
2、Terminal distinction
Can be directly distinguished from the terminals normally open and normally closed contacts, generally speaking, the upper end of the normally closed contacts, the lower end of the normally open contacts, which is the simplest way to judge, but not all can be used to determine the normally open and normally closed contacts, there is also a certain degree of error.
3, accurate measurement with a multimeter
The first: first of all, the multimeter to the through file, that is, the diode beeping file, and then use the two pens are in contact with the two contacts of the button switch, if the beeping, it means that the contact is normally closed (NC), otherwise normally open (NO ). We can press the button again to measure the test, you will find the results are the opposite of the above.
The second: first of all, the multimeter to the resistance block, that is, 1K, with two pens are in contact with the two contacts of the button, the resistance is normally closed point (resistance value is very small, under normal circumstances between 0.2-1, which is the internal resistance of the multimeter), no resistance is normally open point. We can press the button to measure the test again, will find the results are exactly the opposite of the above.
Among them, the calendar meter measurement is the most accurate, you can use more This method to measure, when measuring must pay attention to safety, to avoid When measuring, we must pay attention to safety to avoid unnecessary losses.
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