Multimeter to measure the short circuit open circuit with on-off gear or resistance gear
The on-off position is also called the buzzer position, I believe. This gear, if the actual resistance of the line under test is lower than a value (I forget exactly how much, the manual has a detailed explanation), the buzzer will beep.
Take the digital multimeter, the buzzer seems to be able to measure up to 2 kilohms of resistance.
For example, to measure a section of pure line (such as a roll of 100 metres of wire), the wire is not broken will beep.
Another example is a section of line, in the middle of the line may be connected to some resistive components (such as coils, motor windings) or the line is very long, very long, more barge interfaces, and so on. Measured in this gear, it may not be beeping, but will show a value, then the value is the resistance of the line, and can not be sufficient to show that the line is broken.
Example: you randomly select a good AC contactor coil, with the beeping gear coil measurement at both ends, it will not beep, but will show a value (assuming 758); you then use the 2 kilo-ohm resistance gear and then measured, the measured value is still 758, that is, the coil's resistance of 758 ohms. At this point you cannot say that the coil is disconnected. If the coil is disconnected, the reading will be zero and it will not beep.
If it doesn't chirp and there is no reading, it still doesn't technically mean that this section of the circuit is disconnected. As I said above, the maximum resistance value that can be measured at this level is only 2k ohms. So it is possible that the resistance value of this line is higher than 2 kilo-ohms, then you can change a higher resistance level and then test.
In practice, generally do not need to look so deeply, like the above said a volume of one hundred metres of wire, under the premise that it does not break the circuit, if the buzzer gear will not be chirping when measured, basically, it can be ruled that this volume of line is not as good as.
Another example is to know to measure the motor winding, measurement before their hearts to have a number, beep gear when it does not show the number of not chirping, in order to ensure accuracy, should be changed to a larger gear to measure again.
Anyway, I personally feel that we should pay attention to: 1 buzzer gear can only be measured below 2 kilo-ohm resistance; 2 only when the actual resistance value is lower than the set value, it will beep. Remember this, and then according to the actual situation to prejudge the accuracy of the measured results. Or rather, according to the actual situation to prejudge what gear measurement is most suitable.
To be honest, I am also used to using the beeper to measure on-off. And I use a digital meter, what I said above is also according to the digital meter explanation, mechanical meter is rarely used, said that I do not quite understand.
