Calibration of Digital Weighbridges
The calibration of digital weighbridges before verification is crucial. If the weighbridge can be adjusted to its optimal state before verification, the subsequent verification process becomes much easier and can often yield twice the result with half the effort. Below, I will discuss the calibration of several key aspects of the weighbridge, including Daqing digital weighbridge remote control.
1. Eccentric Load Calibration: The purpose of eccentric load calibration is to ensure that the readings at each support point are consistent or that the errors at each support point are within a certain range, thereby ensuring the accuracy of the weighbridge's measurements. Regulation 3.5.2 stipulates: "For the same weight placed in different positions, the error should not exceed the maximum allowable error for the corresponding weighing capacity." If weights are used for eccentric load testing, it may require repeated adjustments to achieve compliance, involving the repeated moving of weights, which wastes time and effort. A practical approach is to use a small transport vehicle loaded with heavy objects, making its total weight close to 1/(N-1) of the test weight for calibration until it meets the requirements. Then, use standard weights for verification.
2. Repeatability Calibration: The goal of repeatability calibration is to ensure that the weighbridge's readings remain stable and unchanged. Regulation 3.5.1 states: "For multiple weighings of the same load, the difference between results should not exceed the absolute value of the maximum allowable error for the corresponding weighing capacity." Before calibration, arrange for a loaded truck whose weight is approximately 50% of the maximum capacity of the weighbridge being tested. During repeatability calibration, use this truck on the weighbridge for adjustment using the Daqing weighbridge remote control to ensure the results meet regulatory requirements.
3. Clever Use of Substitutes for Weight Calibration: The purpose of weight calibration is to ensure the accuracy of the readings at various weight points of the weighbridge or that the errors at these points comply with regulatory requirements. Regulation 3.5 specifies: "Regardless of how the weighing results change, the error of any single weighing result should not exceed the maximum allowable error for the corresponding weighing capacity." When performing weight calibration, first use the small transport vehicle from the eccentric load calibration for weight testing, achieving 30% of the maximum capacity. Second, use the loaded truck from the repeatability calibration for further weight testing, reaching 50% of the maximum capacity. Third, place both vehicles used in the eccentric load and repeatability calibrations on the weighbridge platform simultaneously for weight point calibration, reaching 80% of the maximum capacity. This method optimizes the weighbridge's performance. Due to traceability factors and differences in weight points, a final calibration with standard weights should be performed. At this stage, the weighbridge's working condition is good, and the calibration can usually be completed in one attempt.
Fault Phenomenon: Unstable display on the weighing instrument.
Maintenance Process: For a 30t electronic weighbridge with an unstable display on the weighing instrument (the displayed numbers fluctuating up and down), the sectional troubleshooting method was applied. Initially, a simulator checked the instrument, which was found to be normal. Self-prepared instruments were then used to check the junction box and sensors, all of which were also normal. Since the wiring was buried underground and difficult to inspect, it was initially suspected that there might be an issue with the wiring. The weighbridge operator mentioned that there had been a heavy rainstorm the previous night, after which this phenomenon started occurring in the morning. This strengthened the suspicion that the problem lay with the wiring. A self-prepared signal cable was used to directly connect the junction box to the instrument, restoring the instrument's normal display. Upon excavating the wiring, it was discovered that the wiring connector was damp. After disassembling it, the signal cable was dried with a hairdryer, rewrapped, and the weighbridge resumed normal operation.