How to measure the voltage of AC contactors A1 and A2 in the powered-on condition using a multimeter
Use a multimeter with an AC voltage of 500 volts to connect directly to A1 and A2
Select the 750V gear of the multimeter AC voltage, look at the position of the jack, put the black and black test leads into the com. red test lead into the V jack, put the red and black test leads at both ends of A1A2, and measure the voltage value
Turn the multimeter to the highest gear and lower it according to the display! If the pointer type must be done, the pointer should be in the middle position, such as a digital electronic watch, the purpose is to reduce the measurement error, and also to reduce the proper gear!
Use a multimeter to measure the AC voltage file, 250v file (when the estimated voltage is 220v) or 500v file (when the estimated voltage is 380v). Connect the two test leads to A1A2 to see the reading.
It is so simple that you can talk about the problem without thinking, first use the Ac high-level measurement to see if the result value is not good or wrong, and then use the Dc high-level measurement
Directly use a multimeter to set the 600V voltage range, and use the test pen to test it. There is no positive and negative poles in the AC power supply, and the test pen measures A1 and A2. It is clear at a glance whether there is power or not.
First determine the known voltage of the terminal to be tested. Most of the factory electricity is ≤380V AC, and the civilian use is 220V AC. Set the multimeter to AC 500V and measure it directly!
How to measure electrolytic capacitor with digital multimeter
1. Use the capacitance file of the digital multimeter to directly measure the capacity
The digital multimeter can measure the capacitance below 20mF (the "mF" here reads as "millifarad", 1mF=1000μF) (the previous multimeter can only measure the capacitance of 200μF at most), so to judge whether the capacitance is good or not, you can use the capacitance file of the multimeter Measure its capacity.
Use a digital multimeter to measure the capacity of the 4700μF capacitor. The reading shown in the figure is 4.502mF, that is, 4502μF. Due to the large error of the electrolytic capacitor, the displayed capacity is normal. When measuring a large-capacity electrolytic capacitor, if the range is not exceeded, the displayed reading is always "1", indicating that the capacitor has a large leakage or has been broken down. If the measured capacitance is much smaller than the nominal value, it means that the internal electrolyte of the capacitor is dry, and it is generally not suitable for use.
2. Use the diode file of the digital multimeter to judge whether it is good or bad
Use the diode file of the digital multimeter to judge the quality of the capacitor. Since the test current of the diode file is relatively large (mostly more than 1mA), the diode file measurement can quickly measure whether the large capacitor is broken down or damaged. When measuring, touch the two pins of the capacitor with a multimeter pen. If it is a good capacitor, the reading displayed on the diode file may be "0.000" in the first ten seconds, and then the displayed reading will gradually increase until it is displayed as " 1". If the reading displayed by the multimeter is 0.000 (or the reading is always small) for a long time during measurement, it means that the capacitor is damaged.
