How to achieve precise and effective liquid level control in industry?

2020-06-18 13:19:07

In view of the current industrial liquid level control, such as water tank, reaction tank and other control systems, a set of implementation schemes for liquid level control using Jingda Instrument Factory XMB-6000 series instruments is proposed, which can effectively, easily and accurately reach the liquid level. Bit control requirements.

With the development of society and the advancement of science and technology, there are quite a lot of liquid level control systems used by factories and enterprises. The liquid level controller controls the high and low liquid levels by mechanical or electronic methods. The solenoid valve and the water pump can be controlled. The liquid level control is widely used, and it is suitable for automatic liquid level control of any water tower, water tank, water tank, reservoir, etc., which can effectively prevent the consequences of water shortage or flooding caused by human factors, and achieve energy saving and consumption reduction. .

System structure The structure of the whole system is shown in Figure 1. According to the functions to be completed by the system, the hardware of the system is divided into the following parts: sensor, main control board, water pump and water tank.

Sensor working principle The liquid level controller (sensor) monitors the water level of the water tank. The different water levels correspond to different liquid pressures. The pressure difference of the liquid directly acts on the double-sided isolating diaphragm of the transmitter sensor and conducts through the sealing liquid in the diaphragm. To the measuring component, the measuring component converts the measured differential pressure signal into a corresponding electrical signal and transmits it to the converter, and processes it into a standard electrical signal output (for example, 4-20 mA) by amplification or the like.

The principle of the instrument control pump is controlled by the drive circuit of the instrument. The circuit diagram is shown below:

The instrument provides a set of normally open contacts AL1. When the water level is lower than the lower limit of the water level, the AL1 contact is closed, the contactor coil is energized, the KMI is normally open, the motor is energized, the pump is pumped; when the water level is above the upper limit of the water level, The AL1 contact is open, the contactor coil is not energized, the KMI is normally open, the motor is not energized, and the pump is not working.

The setting of the meter parameter is controlled by the on and off of the AL1 contact. The on/off of the AL1 contact is controlled by the alarm value inside the meter. Therefore, can the water level in the tank be kept at the normal level? The setting of the alarm parameters is especially important. Now I will talk about how to set the alarm parameters and express them with a formula.

Alarm value ALR.1=(low water level + upper water limit)/2
Return difference HY.1 = (upper limit of water level - lower limit of water level)/2

Since the contactor generally uses a normally open point, the alarm is generally set to low (Lo.AL), and if the contactor uses a normally closed point, the alarm is set to high (HI.AL).

This article takes the XMB-6000 series instrument as an example to discuss the liquid level control system. The system uses the AL1 contact on our instrument to control the start and stop of the pump. It is very simple and practical to operate, and the control precision is quite high. User's praise.