The Principle Of The Load Cell Junction Box And How To Use It

Selection and wiring method of junction box:

1: Overview of the use of the junction box, because the consistency of the load cell is not necessarily ideal when the load cell leaves the factory, coupled with the environmental factors in the field use and the limitations of the installation method, it will bring imbalance problems to the parallel group scale of multiple load cells. In order to solve the above problems, the junction box must be selected to adjust the ratio of the load cell coefficient to the load cell output impedance (mV/V/Ω) to be close to the same, so as to ensure the balance of the entire scale body.

Adjust the level of the mechanical table. For more than four load cells, due to various reasons, the mechanical table and the foundation are more or less deformed. The longer the use time, the more serious the deformation, resulting in inconsistent force on the load cell, only rely on the potentiometer The compensation cannot be compensated, so the height of the load cell should be adjusted first, within the range of the difference (20-40) kg, and then compensated by the potentiometer until it is basically the same. This is an iterative process, due to the mechanical table Deformation, adjusting one corner may affect two corners, or even three corners, only trial and error.

2: Junction box model and naming, junction boxes can generally be divided into: BJ-4/6/8 and other series. JB-4: five-hole junction box with four wires, suitable for electronic scales or systems that use 4 load cells in combination; JB-6: seven-hole junction box with six wires, suitable for electronic scales or systems that use 6 load cells in combination; JB-8: Nine-hole junction box with eight wires, suitable for electronic scales or systems with 8 load cells combined; for electronic scales or systems with more than 10 load cells, the connection can be realized through the combination of multiple junction boxes.

For example: BJ-4-SS, BJ-6-SS, BJ-8-SS will Ningbo Saintbond intelligent junction box Features: BJ-4-SS is used for parallel connection of four load cells, VKK2-6 is used for six load cells Parallel connection, integrated resistance network for four-corner adjustment, Ningbo Saintbond's unique shielding method to complete EMC protection (according to EN45501), can be expanded to more than six load cells (only applicable to BJ-4-SS), protection level IP65 ( According to EN60529), stainless steel casing.

3: Overview of junction box technology:

3.1: Stainless steel or aluminum alloy shell, special sealing joint, durable and good sealing.

3.2: High-precision, low-drift resistors and potentiometers are used to ensure the accuracy and stability of the system.

3.3: The load cell connection and signal cable connection are equipped with special terminals to ensure reliable connection.

3.4: Welding holes for welding wires are reserved beside each terminal post, which can be used for both welding and insertion wiring, and can be selected independently.

3.5: There is a code mark next to the wiring welding point, which is convenient for users to connect.

4: Junction box installation and debugging

4.1: Junction box installation, fix the Ningbo Saintbond intelligent junction box at a suitable position on the scale body. Open the top cover of the junction box. Pass the load cell cable and instrument signal cable through the corresponding interface of the junction box, connect all the cables according to the wiring diagram shown in the figure, and tighten all the nuts after completion. Use sealing rubber gasket or plasticine to block the unused interface, and tighten the nut at the same time. Connect the outer shield of all cable wires to the grounding post of the junction box.

4.2: Junction box debugging, according to the output signal of the load cell, refer to the wiring diagram given in the figure below, and adjust the corresponding potentiometer. (Note: Do not over-adjust the potentiometer) After debugging, cover the upper cover of the junction box and tighten it with screws. )

How to use and pay attention to the weighing junction box:

1: The connection between the load cell and the junction box

Pass the cable of Ningbo Saintbond intelligent weighing load cell through the weighing platform, and enter the junction box through the sealed joint, according to the different color codes of the four-core or six-core cables, or according to the positive and negative excitation power, positive and negative feedback, positive and negative after measurement. The negative signal is connected to the corresponding terminal in the junction box. Bind the remaining cables of the load cell with plastic cable ties.

2: The junction box is connected to the weighing display instrument

Put one end of the special shielded cable into the junction box through the sealed joint, each core wire is connected to the corresponding terminal in the junction box, and the other end is welded to the special plug corresponding to the weighing display instrument through the metal tube, so that it can be inserted into the weighing indicator. Re-display instrument socket.

There are three points to note:

A: After the input and output lines in the junction box are connected, tighten, tighten and seal the joints, put a desiccant, and do a good job of moisture-proofing, and then the junction box board can be fixed;

B: For different load cells, the input, feedback, and output should be distinguished according to different color codes, and there must be no mistake; the weighing junction box

C: For different weighing display instruments, the types of weighing display sockets and plugs used are different, and the connection methods are even more different, so don't make mistakes.

3: System grounding

The grounding of the electronic scale system is very important. It not only protects personal safety, but also ensures the stable and reliable operation of the system. The grounding measures of the system must not be underestimated. Generally, the electronic scale system has two grounding points, one is the grounding pile in the weighing room, which grounds the instrument shell; the other is the grounding of the weighing platform, and one or several grounding cables are used to connect the scale body to the grounding pile.