The inseparable relationship between checkweigher and load cell
time2021/07/08
- Why is the check weighing called inaccurate? I will teach you three methods to check your own check weighing!
The checkweigher may have inaccurate weighing after a long time of use, and the core component of the weighing mechanism is the load cell, which is the key to the inaccurate weighing.
At present, the checkweigher generally uses resistance strain gauge load cell (analog) as the core component of the weighing mechanism. It uses the Wheatstone bridge principle to transform the weight signal into a linearly changing electrical signal. There are conventionally four lines and the input is 5. -10V excitation voltage (supply voltage), the output is a weight signal with "mV" as the unit. Here are three ways to judge good or bad
1: Observation
Observe whether the sensor is deformed or cracked. If these conditions occur, you need to contact the manufacturer to replace a new sensor.
2: Line input and output measurement method
Find the sensor connection terminal in the checkweighing controller, and determine the sensor connection circuit
Under normal circumstances, the excitation voltage (between EXC+ and EXC-) is 5-10V, and the output voltage (between SIG+ and SIG-) is close to 0 when the device is empty, which is less than the maximum output of the sensor. (The maximum output of the sensor = excitation voltage * sensor sensitivity, the sensitivity of the checkweigher sensor is mostly 2mV/V), if it exceeds this range, contact the service provider to apply for a replacement of the sensor.
3: Sensor resistance measurement method
Measure the resistance of the sensor, and judge the quality of the sensor by the resistance
（1）: Input resistance≧output resistance>bridge resistance
（2）: Under normal circumstances, the bridge resistances are equal or equal to each other
(Note: The input resistance is the resistance between EXC+ and EXC-, the output resistance is the resistance between SIG+ and SIG-, and the bridge resistance is between EXC+ and SIG+, EXC+ and SIG-, EXC- and SIG+, EXC- and SIG- Resistance between)
The above is the judgment method of the checkweigher weighing sensor. It should be noted that the weighing sensor is not so easy to be damaged under normal use. Many failures are caused by the improper use of the checkweigher to overload the sensor. Therefore, in the process of using and disassembling and maintaining the checkweigher, we should try our best to avoid heavy objects from hitting and bumping, and operate strictly in accordance with the checkweigher range.
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