How to determine whether a line is broken or shorted with a digital multimeter
Now the use of digital multimeter has been very common, in the line detection, circuit wiring play an important role. The multimeter is the most basic and most commonly used three physical measurements, voltage, current, resistance, the title says exactly the three basic physical measurements.
Voltage Measurement
Digital multimeter for voltage measurement, the multimeter is equivalent to a voltmeter, so the multimeter will be connected in parallel on the line of the electrical components or power supply terminals. Measurement of the voltage measured before the clear is AC or DC, but also to estimate the maximum voltage value, and then select the corresponding AC voltage range or DC voltage range gear range. If you do not know the size of the voltage, it is appropriate to use the maximum voltage range gear is safer.
Measurement of current
When measuring current, the digital multimeter is equivalent to an ammeter. Therefore, the multimeter is connected in series with the measured circuit. Measurement of current before also to distinguish between DC current or AC current, in the estimation of its current current maximum value, and then select the corresponding AC current gear range bit or DC current gear range. If the value of the unknown current size, it is appropriate to use its maximum range is safer.
Judge the line is broken or short-circuit?
Ensure that the line is not electrified, in order to carry out testing and judgment. Short circuit is from the power supply out of the line does not go through the load and directly connected, is equivalent to the power supply ends directly with the wire connection. If it is AC power, it is the fire wire and zero wire together. At this point, as long as the power supply is thrown off, measured with a digital multimeter resistance level, the resistance is very small or zero, which means that there is a short circuit in the line. You can also use the multimeter buzzer gear, if there is a short circuit multimeter buzzer beep.
Line break judgment
The three elements of the circuit is the power supply, load, intermediate links. As long as one of the elements do not meet the circuit can not constitute a circuit. Ensure that the power supply is normal, then the disconnection may occur in the load or intermediate links. The prerequisite is that there is no short circuit in the line and then energize the line. If you measure the voltage across the load, it means that there is no break in the line, but the load is damaged. If there is no voltage at both ends of the load, it means that there is a circuit break in the intermediate link, which may be an open wire or an open auxiliary device.
