Three Tips for Using a Multimeter to Identify Problems
1. How to Record Intermittent Faults with a Multimeter:
Use the minimum/maximum/average value recording mode of the multimeter, and select the corresponding function (AC voltage, DC voltage, resistance, AC current, DC current, and frequency) according to the measurement item. Ensure that the test circuit is connected before activating the minimum/maximum/average value function. Otherwise, the minimum value reading will always be the ambient value before the test leads are connected. This will affect the analysis of the recorded data after the recording time ends. Activate the minimum/search maximum/average value recording mode. The multimeter display will indicate the maximum reading, and it will emit a beeping sound when a new maximum or minimum value is detected.
The advantage of this is that when it is ensured that the digital multimeter will not be tampered with and will not pose any safety hazards to anyone, the digital multimeter can be left in place for measurement while you focus on other work. At any time during the recording period, you can view the saved readings, or pause the recording mode without deleting the saved readings.
2. How to Continuously Record Intermittent Faults with a Multimeter:
Some multimeters not only have the minimum/maximum/average value recording function, but also combine this function with another function called AutoHOLD and a larger memory to form the Event Logging function. The AutoHOLD function can sense when the measurement signal becomes unstable and when it becomes stable again. By using the AutoHOLD function to trigger the start and stop of the minimum/maximum value recording function, the digital multimeter is not limited to detecting faults that produce minimum or maximum values.
If the multimeter has an infrared RS232 interface, the continuous recording function will be even more powerful, and it can become a simple event collector, transmitting the data collected by the multimeter to a computer. With the computer, you can conduct a detailed analysis of each stable and unstable event. You can not only view the minimum and maximum values within each stable and unstable cycle, but also view the start and end times of each cycle. In addition, the average value of each cycle is also recorded. At the same time, you can dynamically detect the change trend graph of voltage or current.
3. How to Mark the Recording Time with a Multimeter:
The time when the minimum and maximum values are detected is very useful information for determining the cause of intermittent faults. The digital multimeter can store the amount of time from the start of recording to the saving of a new minimum, maximum, or average value in the minimum/maximum/average value recording mode. Therefore, each saved minimum, maximum, and average value has a corresponding "time stamp".
Now, digital multimeters with digital acquisition or storage functions, through a computer or their own memory, also have the same strip recording function. If the digital multimeter has the function of the minimum/maximum/average value recording mode, just like a paper tape recorder, the digital multimeter also reads the input readings at certain intervals. But unlike a paper tape recorder that saves each reading, it compares the reading with the previously saved reading to determine whether the value is higher than the previous maximum value or lower than the previous minimum value. If so, the new reading will replace the value originally saved in the high or low reading register. After a period of recording, you can call up the values of these registers for display and view the maximum and minimum values within the recording time.
