Continuously record intermittent faults with a meter
Some multimeters not only have min/max/average recording functions, but also combine this feature with another feature called AutoHOLD and larger memory to form Event Logging. Gong Qing.
Automatic power maintenance can sense when the measurement signal becomes unstable and when it becomes stable again. Using the auto-hold function to trigger the start and stop of the min/max value recording function allows the digital multimeter to not be limited to detecting faults that produce minimum or maximum values.
If the multimeter has an infrared RS232 interface, the continuous recording function will be more powerful, and it can become a simple event collector to transmit the data collected by the multimeter to the computer.
Using computers, each stable and unstable event can be analyzed in detail. From: Home of Electrical Technology
Not only can you view the minimum and maximum values within each stable and unstable period, but you can also view the start and end times of each period. In addition, the average value for each period is recorded. At the same time, the changing trend of voltage or current can be dynamically detected.
Multimeter marks record time
The time when minimum and maximum values are detected is very useful information for determining the cause of intermittent failures. A digital multimeter in Min/Max/Avg recording mode can store the amount of time between starting a recording and saving a new minimum, maximum, or average value. Therefore, each saved minimum, maximum and average value has a corresponding "time stamp".
Nowadays, digital multimeters with digital acquisition or storage functions also have the same strip recording function through computers or their own memory.
If the digital multimeter has a min/max/average recording mode function, like a tape recorder, the digital multimeter will read the input readings at regular intervals.
But unlike a paper tape recorder that saves a reading, the reading is compared to the previously saved reading to determine if the value is higher than the previous maximum or lower than the previous minimum. If so, the new reading is replaced. The value originally held in the high or low reading register.
After recording for a period of time, you can call up these registered values for display and view the maximum and minimum values within the recording time.
You can easily calculate the actual time when the DMM detected the reading by simply recording the times when the Min/Max/Avg recording modes were activated respectively.
For example, let's say you activated recording mode at 3:07:00 PM and the maximum reading displayed has a time stamp of 47:05. Simply add the time stamp and the start time to determine the time when the maximum value was recorded. .
Diagnosing intermittent faults is very effective using the digital multimeter's min/max/average recording modes.
However, it assumes that the connected circuit point is capable of exhibiting a maximum or minimum value at the time of the fault. If a temporary fault causes a reading between the maximum and minimum values, then the minimum/maximum/average values are function will not be too helpful in determining the cause of intermittent failures.
During minimum/maximum/average recording mode measurements, do not disconnect the test leads from the circuit under test before pressing the HOLD button to stop recording, or before viewing and archiving all saved values.
Disconnecting a test lead while recording will cause the multimeter to process values that appear on the disconnected test lead, affecting the average value saved when the test lead is connected, and may affect the saved minimum or maximum value.
