Generally, when customers ask about the use of the weighbridge, we refer to the instructions for the instrument. However, the use of instruments is limited by various conditions and factors, which are generally not described in the instructions. Some customers have unclear requirements on instrument selection, system configuration, site conditions and environment, lack necessary understanding of system maintenance, and sometimes the supplier and the supplier misunderstand. In order to avoid such unpleasant phenomena, it is necessary to fully communicate with users.
A brief introduction is given to the environmental impact related to the use of the weighbridge.
1. Impact of service conditions: The use of instruments is affected and limited by the conditions as follows:
1) Site factors
Some customers have defective premises. The installation position of weighing instruments (mainly instruments and sensors) does not meet the requirements, and there are vibrations, dust, smoke, corrosive gases, etc. on the site. For example, the weighing platform foundation of some weighing instruments is built in the abandoned garbage dump, river channel, waste water pit, etc. The weighing platform beside the open road, or even the phenomenon that some customers set up the weighing platform near the mountain top, is unreasonable.
2) Environmental factors
The use environment of some customers greatly exceeds the design requirements of weighing instruments (mainly instruments and sensors). The instruments and sensors are close to strong electric and magnetic fields. There are radio stations, substations, high-power pump stations, boiler rooms, heat exchange stations, discharge outlets, and regional temperature changes violently, and there are flammable and explosive substances, all of which are unreasonable.
3) Customer understanding factors
Some customers have misunderstood the relevant functions and proposed that they do not meet the design requirements, but the constructors did not propose in time, resulting in dissatisfaction of users. For example, the user thinks that since there is a long line compensation function, the distance between the platform and the instrument (control room) is required to be 200 meters; Some users propose that the communication distance of RS232 is 150 meters; The distance between the printer and the instrument is 50 meters, etc. For example, the accuracy of the weighing instrument required by the user is 1/3000, and the accuracy of the control area of the system (with control function) cannot be reached. Why can't the printer be printed if it is unstable or does not return to zero? These are all misunderstandings caused by failure to communicate.
2. Impact of use environment
1) Site change
Some weighing instruments have changed due to the environment of the site, and users are used to it and do not notice it. For example, the foundation of a truck scale is built near an abandoned pond, and the weighing changes due to the settlement of the foundation.
2) Environmental changes
For example, there is a chronic micro leakage in the pipeline near a weighbridge, which causes oxidation of the connection port between the instrument and the sensor, instability of the resistance value, and fluctuation of the weighing display; The cable of the sensor junction box of a weighbridge has been damped for a long time, the insulation is reduced, and the weighing is inaccurate; After the electrical circuit transformation, some users chose the wrong position of the grounding point, which led to the change of the system reference.
3) Equipment changes
Some users have changed some parts due to equipment transformation, so it is impossible to completely restore the state of calibration during this process, and the system display value changes and the accuracy decreases; Another example is that when the sensor is replaced, the weighing changes due to the difference in sensor performance; For another example, the response speed, voltage stabilization mode and grounding mode of the switching voltage regulator have changed, resulting in the system not working; After the components of control equipment (including power transformer) are replaced, the change of parameters may cause the change of weighing.
3. Human influence
1) Some users are not familiar with the principle of weighing instrument debugging and use, so they have unexpected failures. For example, in calibration, there are few or no weights, and heavy load weights are placed on the platform for a long time, and the platform is impacted or impacted; The scale platform is used as a working platform for electric welding, and the random insertion and removal of wires during operation are all human factors.
2) The system fails due to the misoperation of some commissioning personnel. Some users failed due to changes in operators. For example, the printing and output of reports, the operation of computer management system, and the parameter setting of control system are greatly affected by the habits of personnel.
3) When some users correct the deviation of the system, the input parameters are inconsistent, resulting in system function problems. For example, set the zero adjustment range to 0, so that the zero tracking function of the system disappears; For example, after resetting the zero setting range, the manual zero setting range is reduced due to unreasonable parameters; For another example, after the print parameters are modified, the print format and print method will change accordingly. However, users do not understand the changes of system functions due to the changes of parameters, which brings some unnecessary troubles, misunderstandings and losses.
4) , Skill Impact
A. Some commissioning (after-sales service) personnel improperly improved the accuracy of the weighing display according to the customer's suggestions, resulting in poor results. The accuracy of the system depends on many factors, sometimes not the instrument and sensor can achieve. For example, for a 30 ton weighbridge, six 30 ton sensors are used, and the graduation value is 10kg (the customer proposes to increase the safety factor of the sensor). In this way, the resolution of the system is much higher than that of the sensor. How can it work normally? For another example, some debugging personnel arbitrarily lengthen the sensor connection line of the instrument without long line compensation to 30 meters, and the RS232 communication connection line arbitrarily lengthen to 100 meters. The scale of the system shows obvious drift fluctuations, which is naturally unacceptable to users.
B. Some users are not familiar with the connection method of the instrument, and some others do not read the manual, but connect the instrument by imagination, guess, and estimate, resulting in damage to the instrument. For example, if pins 9 and 10 of the instrument are used as calibration ports and short circuited, the large screen interface will be damaged, and then the large screen will be damaged; if pins 7 and 8 of the instrument are used as calibration ports and short circuited, the communication interface will be damaged; if the plug originally connected to Toledo 8142-07 instrument is connected to Yaohua XK3190 instrument, the analog circuit of the instrument will be damaged, Some users even plugged the original 15 core special micro printer plug into the 3190 standard 15 core socket, seriously damaging the hardware structure of the system, making the system unable to work, and some seriously burned the computer communication interface.
4. Maintenance impact
Any equipment needs to be maintained. As measuring equipment, the maintenance of weighing instrument is particularly important. Due to improper maintenance or no regular maintenance, some users' systems have unexpected failures.
1) Clean the casing with strong solvent. Damaged membrane switch.
2) . The liquid or other conductive particles were inadvertently injected into the instrument, and were not cleaned or dried in time afterwards, causing short circuit or drift inside the instrument.
3) Due to the invasion of humid environment or corrosive gas or the accumulation of fine dust, the analog part and high-voltage part of the instrument are subject to electric leakage and short circuit, and some integrated circuits are damaged, so the instrument cannot work normally.
4) The sensor junction box failed to be maintained in time, the wiring was loose or the contact was oxidized, or the instrument input circuit failed due to the bite of small animals.
5) . The connection line of the system is not fastened in time, the plug is loose, the input and output circuits of the instrument, printer, computer and controller are damaged, the integrated circuit is damaged, and the system is paralyzed.
6) The sensor must be checked frequently to prevent force transmission failure due to various reasons, such as adjustment of overload and eccentric load limit, adjustment of limit screw, etc.
7) Maintenance of grounding system of the system (mainly referring to instruments and sensors). The grounding system of the system may be damaged due to factors such as vibration, oxidation and external force, so it must be adjusted in time. Otherwise, the failure caused by poor grounding is likely to damage the instrument, sensor, printer, computer and controller.