​Common failure and prevention of floor scale(1)

Common failure and prevention of floor scale(1)

Examples of common floor scale faults

As a measuring instrument with accurate measurement, fast weighing speed and convenient use, floor scale has been applied more and more in internal logistics turnover of enterprises and foreign trade. In recent years, due to various floor scale manufacturers, large price difference, high frequency of use, improper maintenance and other reasons, the failure rate of floor scale has become a trend of increasing year by year. As a weighbridge surveyor, the author gives some simple examples of common faults:

1.1  A grain depot used 60 t electronic floor scale value obviously lower than the standard values significantly, using simple pressure Angle (Angle in a mini into various scales, see the feet have output without obvious difference) on-site inspection found no output value for a sensor, check the sensor signal lines found has been damaged fracture, bite by the rat, reconnect the signal lines, floor scale returned to normal. So in the grain depot to take anti-rat  measures, such as the connection line to cover the hose, scale bottom shop scattered rat poison.

1.2  After a rainy day, a 100T floor scale of an enterprise appeared zero drift and the value was unstable. After inspection, it was found that the connection line between the junction box and the display instrument had been broken. For the connection bus, try to keep the bushing buried underground to prevent it from breaking due to rolling, and for the connection that has been broken, reconnect it and use the heat-shrinkable tube to avoid dampness.

1.3  In summer, the value of a weighbridge drifted during the early evening weighing, and remained stable after 10 o'clock in the morning. Check the junction box and find that the junction box is not well sealed, and there is water at the bottom of the box, which is in the middle. The temperature is high in the afternoon, water vapor will form, and the temperature is low in the evening, water vapor will form, and water droplets will be attached to the circuit board, causing the value drift. In the rainy season, especially pay attention to the closure of the junction box, also can be in the junction box above the construction of a waterproof board.

1.4  After a certain floor scale is put into use for a period of time, it is found that the meter often does not return to zero, and the base number of -20kg or -40kg appears. When the floor scale reaches 60 tons, the time difference is about 200kg. After inspection, it was found that the concrete of the base of a sensor cracked, causing the bottom plate of the sensor to sink. It is time-consuming and laborious to solve foundation faults, so we must strictly check the infrastructure before the floor scale is installed, especially in northeast China.

1.5  The weight of a car varies greatly when it stays in front and behind. First, check whether there is a foreign body around and under the scale body, check whether the limit is dead, if excluded, check the sensors one by one, finally determine the damage of a sensor, replace the sensor troubleshooting. Sometimes, the output value of the sensor is not much different from the standard value. In this case, it is necessary to measure the input impedance and output impedance of the sensor by multimeter.

1.6  A floor scale shows normal value when the vehicle is not loaded, and the scale is obviously lower than the standard value when the heavy vehicle enters. It is found that there is a stone at the bottom of the floor scale body. When the heavy vehicle enters, the floor scale body sinks down on the stone, and the floor scale will return to normal after removing the stone. The user should develop the habit of checking around and at the bottom of the scale body frequently to ensure that no foreign body touches the scale body and to observe the limit device, which is generally controlled at 2-3mm.