Tips for Measuring Leakage Current with a Digital Multimeter
Measure the leakage voltage of the soldering iron using the AC voltage range of a digital multimeter.
As shown in the above figure, when measuring the leakage voltage of a soldering iron using the AC voltage range of a digital multimeter, the digital multimeter should be adjusted to the AC voltage range first (the one used in the figure is an automatic range changing digital multimeter), and then one probe should be used to contact the soldering iron tip, and the other probe should be used to contact the ground wire (or earth). At this time, the AC voltage displayed on the multimeter is the leakage voltage. If the soldering iron is not grounded, the soldering iron tip will have a higher leakage voltage at high temperatures. Due to the round grounding terminal of the electric soldering iron plug in the picture, it cannot be inserted into a general socket (it can be inserted with a universal five hole socket), so the grounding terminal of the plug has been cut off. Although the socket has a ground wire, the soldering iron is not grounded, so there is a leakage voltage displayed.
During testing, the red probe is connected to a screw through a small piece of solder wire, which is connected to the ground wire of the socket on the production line. In the above figure, the measured leakage voltage is 42.51V. It can be seen that the ungrounded soldering iron still has a high leakage voltage at high temperatures.
When the soldering iron is not connected to a power source, the multimeter displays an AC voltage of only 20.9mV.
The above picture shows that when the soldering iron is not connected to a power source, the multimeter displays an AC voltage of only 20.9mV. This reading is an interference signal in the AC voltage range, and the number is constantly jumping. As can be seen from the figure, the grounding terminal of the temperature regulating soldering iron plug has been cut off.
2. Measure leakage current with a digital multimeter
Measure the leakage current of the soldering iron using a digital multimeter in AC current mode.
When measuring the leakage current of electrical equipment with a digital multimeter, first adjust the multimeter to the AC current mode (if it is an automatic range changing multimeter, adjust the range switch to the minimum AC current mode), and then connect the red and black probes according to the above method. The reading displayed on the multimeter is the leakage current. In the above figure, the leakage current of the soldering iron is shown to be 5.4 μ A.
