The reliability of data collectors directly determines the accuracy, stability, and continuity of long-term data collection, especially in scenarios such as industrial site monitoring, long-term environmental observation, and equipment fault diagnosis. Evaluating its reliability requires comprehensive verification from four dimensions: core performance stability, environmental adaptability, anti-interference ability, usability, and maintainability, combined with the requirements of actual application scenarios.
1、 Core Performance Stability Assessment
The long-term stability of core performance is the foundation of reliability, and it is necessary to focus on verifying the continuity of the three major indicators of data collection accuracy, sampling synchronization, and data integrity.
The long-term consistency testing of collection accuracy is the core of data collection, but achieving a single accuracy standard does not necessarily mean long-term reliability. Full range and long-term stability testing is required.
Testing method: Connect the collector to a standard signal source (such as a high-precision voltage/current source, function generator), covering the entire range of the collector (such as 0-10V, 4-20mA), and run continuously for 72-168 hours under rated working conditions (simulating long-term working conditions). Record the collected values at fixed intervals (such as 1 hour) and calculate the deviation from the standard values.
Evaluation indicators: Focus on zero drift and range drift - zero drift refers to the change in the collected value when the input is zero, and range drift refers to the deviation change in the collected value when the input is full range; The drift of a reliable collector should be controlled within the allowable range indicated in the manual (such as ± 0.01% FS/℃, FS is full range), and the drift trend should be stable without sudden changes.
Addendum: If the collector supports multiple channels (such as the dual channel you are concerned about), the accuracy consistency of each channel needs to be tested separately. The inter channel deviation should be less than the inter channel error marked by the device (such as ≤ 0.02% FS) to avoid data distortion caused by inter channel interference.
The reliability of sampling synchronization and temporal stability is crucial for scenarios that require multi-channel synchronous acquisition, such as vibration phase analysis and multi-sensor collaborative monitoring.
Testing method: Input standard signals of the same frequency and phase (such as 1kHz sine waves) to multiple channels, continuously collect for a period of time, and analyze the timestamp deviation and phase difference of each channel's data.
Evaluation criteria: The synchronization error between reliable collector channels should be less than 1% of the sampling period (such as synchronization error<1 μ s at a sampling rate of 10kHz), and there should be no significant accumulation of synchronization error during long-term operation; If the collector supports external triggering, it is necessary to test the timing consistency between the triggering signal and the sampling start to avoid triggering delay fluctuations that affect data correlation.
Data integrity verification: Data loss and errors are fatal issues for the reliability of data collectors, especially in scenarios with large amounts of data and long-term data collection, which require key verification.
Test method: Set the collector to continuously collect data at the maximum sampling rate, store it locally or upload it to the upper computer, run it until the device is fully stored or lasts for more than 24 hours, calculate the difference between the total number of collected data points and the theoretical number, and calculate the packet loss rate.
Evaluation criteria: A reliable collector should have a packet loss rate of less than 0.001% and no continuous packet loss phenomenon; At the same time, verify the data verification function (such as CRC verification) to ensure that there are no data errors during transmission or storage, and the error rate should be below the level of 10 ⁻⁹.
2、 Environmental adaptability assessment
The working environment of the collector (temperature, humidity, vibration, etc.) is an important factor affecting reliability, and its performance retention ability in extreme environments needs to be verified.
Temperature and humidity adaptability testing requires testing the performance of the collector within the rated and extreme temperature and humidity ranges due to significant fluctuations in temperature and humidity in industrial and outdoor environments.
Testing method: Place the collector in a high and low temperature humid heat test chamber, set it to rated working temperature and humidity (such as -10 ℃ -60 ℃, humidity 10% -90% RH) and extreme temperature and humidity (such as -20 ℃, 70 ℃, humidity 95% RH beyond the rated range), and stabilize for 2 hours in each environment. Repeat the core performance stability test and compare the accuracy and drift changes under normal temperature and humidity.
Evaluation criteria: Within the rated temperature and humidity range, the performance indicators of the collector should not show significant changes (drift variation ≤ 50%); Under extreme temperature and humidity conditions, there should be no malfunctions such as crashes or data loss. The performance indicators should change within an acceptable range (such as drift variation ≤ 100%), and the performance can be restored after returning to normal temperature and humidity.
The anti vibration and anti impact capabilities of the collector need to be verified for the reliability of its mechanical structure and internal components in scenarios such as industrial equipment and vehicle mounted environments where there is continuous vibration or impact.
Testing method: Conduct vibration testing according to industrial standards (such as IEC60068-2-6), apply vibration frequencies (such as 10-2000Hz) and accelerations (such as 1g – 5g) that match the application scenario, and continue vibration for 2 hours; The impact test is conducted by applying a pulse impact (e.g. 10g, lasting for 11ms) according to IEC60068-2-27.
Evaluation indicators: During the testing process, the collector should work normally without data interruption or crash; After testing, the machine was disassembled and checked for any loose internal components or detached solder joints, and there was no significant decrease in core performance indicators.
The power supply voltage in industrial sites may fluctuate during power adaptability testing, and portable collectors rely on battery power supply to verify power adaptability.
Testing method: For AC powered collectors, adjust the input voltage to fluctuate within the range of 85% -110% of the rated voltage (such as 220VAC fluctuating to 187V -242V), and test the stability of the collector's operation; For battery powered collectors, test the performance changes of the collector during the entire process of battery voltage from full charge to undervoltage, as well as the reliability of the low voltage protection function (to avoid equipment damage caused by undervoltage).
Evaluation indicators: Within the voltage fluctuation range, the collector has no restart or data loss phenomenon, and the accuracy drift is ≤ the allowable range; When the battery is powered, the low voltage alarm is triggered in a timely manner, and the data can still be collected stably for a period of time (such as 10 minutes) after the alarm, ensuring that the data can be backed up.