Which is more anti-interference, digital multimeter or pointer multimeter
Speaking of my usage experience, I first used a pointer multimeter. When using it, for example, the resistance range sometimes needs to be set to zero. When measuring voltage, I start measuring from the high gear to prevent the meter from burning. In addition, when measuring, I also need to keep it stable, and when reading values, my line of sight should be perpendicular to the dial surface. Due to significant human and environmental interference.
On the contrary, a digital multimeter does not have the aforementioned drawbacks and has a high input impedance, so there is no need to worry about burning the meter.
But a pointer type multimeter has an advantage of being intuitive when measuring parameters.
The digital multimeter has relatively low requirements for the operating environment, a wide range of applications, strong anti-interference ability, and intuitive viewing of parameters.
The analog multimeter has a large volume, is inconvenient to carry, has high requirements for the usage environment, poor anti-interference ability, and is inconvenient to read, but has high accuracy.
Of course, the anti-interference ability is better with a pointer type multimeter. When measuring some electrical parameters, such as the voltage at certain points inside the frequency converter, the digital multimeter will read randomly and cannot be read. A pointer type multimeter does not have this problem, but its accuracy and ease of use are worse than a digital meter. In short, both have their strengths and weaknesses.
There are two types of pointer watches: internal and external magnetic. Due to the influence of static electricity, the error is too large. If you rub the watch needle on the dial glass, it will not return to O. The digital watch has its own advantages, but each has its own length.
There is no need to measure short circuits, and there are obvious or even huge acoustic and optoelectronic phenomena. For tripping caused by this reason, as long as the cause of the short circuit is eliminated, check whether the contact of the air switch has been burned by the short circuit current. Disconnect the superior power supply to ensure that the air switch is in an absolutely dead state. Close the air switch and measure the three-phase incoming and outgoing wiring terminals of the switch using a multimeter's ohm range. If the conductivity is good, you can power on and try it out. If the phase is missing, there is no need to say more. Replace the air switch.
If a short circuit occurs in the air switch, there is a possibility of the terminal being broken down. You can use a megger to measure the insulation resistance between each terminal (or use a multimeter to measure at a gear of 20K or higher, and remove the incoming and outgoing wires on both sides of the air switch). If the pointer of the dial indicator quickly deflects to the right at the beginning of shaking, it indicates that the interphase insulation of the air switch has been broken down and cannot be used anymore. If the insulation resistance is high, several megaohms or more, it can be powered on for trial use.
How to use a multimeter to detect the cause of air switch tripping
The procedure for powering on the trial is as described earlier. Disconnect the previous power supply, close the air switch that has been repaired, and then close the previous power supply switch. If the power supply is normal and there are no abnormal sounds or odors, the air switch can continue to be used.
Overload. Overload is one of the reasons for frequent tripping of air switches. Touching the air switch that is overloaded and tripped with your hand usually makes you feel that the shell is relatively hot, or even hot to the touch. This will cause a protective action on the thermal components inside the air switch.
Measure the working current of the air switch using the AC current range of a multimeter. If the working current exceeds the rated current of the air switch and continues to operate, a higher level of air switch should be replaced based on the actual working current.
Misoperation. When the inlet and outlet wires of the air switch are aluminum wires, it is easy to react with the copper terminal blocks of the air switch, causing heat at the terminal blocks. The thermal protection device inside the air switch is deformed due to heat, resulting in a protective action. This is a typical malfunction. As long as copper aluminum terminal blocks are pressed onto the aluminum wire and tightly combined with the air switch terminal blocks, this problem can be solved.
