The truck scale is a kind of trade settlement measuring instrument that is used frequently. This paper introduces the principle and structure of the electronic truck scale, analyzes the common faults, and puts forward the troubleshooting and daily maintenance methods, which have guiding significance for the correct use of the electronic truck scale.
Electronic truck scale is a large-scale weighing and measuring equipment widely used by enterprises today. Because of its advantages such as perfect functions, digital display of weighing values, high resolution, convenient weighing, remote transmission of weight signals, and stable and reliable working performance, electronic truck scale has been used more and more widely. However, due to the influence of its working environment and other factors, electronic truck scales often have various failures.
1、 Structure and working principle of electronic truck scale
System composition: The electronic truck scale is mainly composed of three parts: display instrument, weighing sensor and scale body. Working principle: When the weighed object or truck is placed on the weighing platform, under the action of gravity, the weighing platform transmits gravity to the weighing sensor, which converts the weight into an electrical signal in direct proportion to the weight. After the signal is filtered, amplified, and converted to digital analog by the display instrument, it becomes a reading that is directly displayed in the instrument window.
2、 Failure description of electronic truck scale
The electronic truck scale is composed of many components, each of which or the change of the external environment may cause faults, such as abnormal instrument display, unstable display value, large error, etc. But in the final analysis, it is nothing more than mechanical aspects, electronic circuits and external factors. Mechanical failures, such as scale deformation, foreign matters against the scale, abnormal limit, etc; Electronic circuit failures, such as failures of junction boxes, load cells, signal lines, weighing display instruments, etc; The external factors are mainly the influence of power supply, lightning, impact, etc. on the electronic truck scale. In daily work, to eliminate the fault, we first need to know the cause of the fault, find the location of the fault, then we can suit the remedy to the case, further test and check, and finally repair the electronic truck scale.
3、 Common fault analysis and handling
In the daily verification of electronic truck scale, we often encounter problems of one kind or another. Here, combined with the fault phenomena I encountered in my work, some fault analysis and treatment are given as examples.
1. The instrument does not return to zero or the zero position is unstable
Fault analysis: the foundation is not firm, the limiting device is blocked, the grounding is poor, the cable is damaged, and there are sundries between the platform and the foundation.
Fault treatment: check whether the foundation settlement occurs. Because the weight borne by the electronic truck scale is large, the foundation settlement is likely to occur. If settlement occurs, the foundation supporting the scale will be padded; Check whether the limit device is dead, if so, adjust the distance between the limit device and each component; Check whether the grounding is in good contact. If the contact is not good, reconnect the grounding wire; If the cable is damaged, replace the damaged cable; Check whether there is any foreign matter standing against the scale body between the scale platform and the foundation, and clean it if there is.
Electronic truck scale
2. Small load is normal, and large load becomes smaller
Fault analysis: (1) There are foreign matters at the bottom of the scale. When the scale body is loaded, the foreign matters are against the bottom of the scale body, making the weight smaller; (2) The clearance between the sensor and the limiting device is too small; (3) The clearance between the sensor and the unloading bolt is too small, causing the bolt to counter the sensor during heavy load.
Troubleshooting: (1) Check whether there is any foreign matter at the bottom of the scale body against the scale body. If any, clear it; (2) Check whether the sensor touches the limiting device, and make sure that there is a certain gap between the sensor and its surrounding limiting device; (3) Check the clearance between the sensor and the unloading bolt. If it is too small, readjust the unloading bolt to make it have a certain clearance with the sensor.
3. The display instrument (XK3190-A9) displays Err05
Fault analysis: (1) the sensor signal wire is inversely connected (2) the sensor is damaged; (3) The connector drops
Fault analysis: (1) Check whether the sensor signal wire is connected reversely. If it is connected reversely, replace the two wires connected reversely; (2) Use a digital multimeter to check whether the input and output impedance values of the sensors are normal, or disconnect the sensors one by one to see whether the instrument display is normal, if not, replace the damaged sensor; (3) check whether the connector is in good contact with the display instrument, and if not, plug it in again; Or check whether the signal wire of the connector falls off. If it falls off, solder it with a soldering iron.
4、 Example of Troubleshooting for Electronic Truck Scale
Example 1: A 60T electronic truck scale in a rice processing plant displays the load after installation, and cannot be reset by pressing the reset key.
Fault analysis: (1) The sensor is damaged; (2) The limiting device touches the sensor.
Troubleshooting: After asking the welder, it was his improper operation that caused the welding current to pass through the sensor and burned the internal circuit of the sensor. After replacing the sensor, the display instrument returns to normal.
Example 2: A 80T electronic truck scale of a company in our city has a strange fault. The instrument does not return to zero when it is turned on in the morning, and the display is negative. After the manual reset, the zero point gradually increases, and the weight is obviously low when weighing. Its zero point gradually improved over time, and it basically returned to normal at noon. Weighing was also gradually normal, and everything was normal in the afternoon.
Fault analysis: according to the fault phenomenon of the electronic truck scale, it can not work in the morning, and it returns to normal in the afternoon. The analysis may be related to the temperature. At the same time, it is judged that there is no problem with the electronic circuit and components according to the fault phenomenon. It is estimated that there is foreign matter under the scale body.
Troubleshooting: check that under the scale body, a large amount of pulverized coal is collected and directly pushed to the scale body. After more than an hour of cleaning, a lot of wet pulverized coal is cleared, and the electronic truck scale returns to normal. It turned out that this scale had been used to weigh the coal transport vehicle for a long time. After the coal powder fell, it was not timely cleaned and gathered under the scale body. After the coal powder absorbed water, the temperature at night was very low, and the wet coal powder was frozen into a hard block against the scale platform, causing a failure. When working in the daytime, with the increase of temperature, the frozen pulverized coal gradually melts. Because the weather is still very cold, the frozen pulverized coal melts very slowly, and it returns to normal only after it is completely melted in the afternoon.
5、 Daily maintenance of electronic truck scale
Electronic truck scale is an important measuring instrument for trade settlement and is a measuring instrument for key management. It has high value and high maintenance cost. Do a good job in the daily maintenance of the electronic truck scale, which can ensure the accuracy and reliability of the measurement value, maintain the fairness and justice of the transaction, extend the service life, save the operating cost of the enterprise, and improve the efficiency. The key points of daily maintenance of electronic truck scale are as follows:
(1) Establish and improve the daily maintenance system, and assign special personnel to manage
(2) Do a good job of regular cleaning and maintenance, and keep the platform, bottom and surroundings clean and free of debris
(3) Frequently check whether the clearance of the limiting device is normal
(4) The electronic truck scale should keep the drainage system unblocked
(5) Keep the junction box dry, and regularly check whether the cable is damaged
(6) The speed of vehicle weighing shall be controlled within 5km/h. It is strictly forbidden to brake on the weighing platform
(7) It is forbidden to weld things on the scale platform
(8) Before plugging and unplugging the instrument and connecting it with external equipment, the power supply of relevant equipment must be cut off.