Wiring methods for different output modes of material level switch

The material level switch is a widely used material level measuring instrument for measuring powder and solid particles. Many instrument users do not know how to wire the equipment correctly, which often causes the material level switch to fail to work properly or even be damaged. So, how should the material level switch be wired during use? In order to help instrument users master the correct wiring method of the material level switch, the following takes the Tube-11 vibrating rod material level switch and the Fork-11 tuning fork material level switch as examples to explain how to wire the material level switch correctly under different output modes. The introduction is as follows:

The current output methods of material level switches are roughly divided into: relay output (the most commonly used output method, Figure 1), transistor output (less commonly used), non-contact output (less commonly used), NAMUR output (less commonly used) ) and two-wire output (second only to relay output, Figure 2). Since the three output modes of transistor output, contactless output and NAMUR output are rarely used, this article will not introduce them, focusing on the two wiring modes of relay output and two-wire output.

1. Wiring method of material level switch in relay output mode.

Figure 1 is the wiring diagram of Tube-11 vibrating rod material level switch and Fork-11 tuning fork material level switch in relay output mode. Jiwei's power supply design adopts AC and DC intelligent identification, which brings great convenience to power wiring, as shown in:

Figure 1 Relay output mode wiring diagram

1. If the on-site power supply is DC, the DC range is required to be within the range of 20 to 72VDC. The positive pole of the power supply is connected to pin 1 of the instrument wiring strip, and the negative pole is connected to pin 2 of the instrument wiring strip.

2. If the site is powered by AC and the voltage range of AC is 20~253VAC, then the live wire is connected to pin 1 of the instrument wiring strip, and the neutral wire is connected to pin 2 of the wiring strip.

3-4-5 and 6-7-8 are double pole double throw (DPDT) output terminals. The two sets of switches are opened or closed synchronously. 3-4 and 6-7 are normally closed contacts, and 4-5 and 7-8 are Normally open contact. That is to say, when power is off, the relay is released, correspondingly 3-4 is connected and 4-5 is disconnected; similarly, 6-7 is connected and 7-8 is disconnected.

Whether to use normally open (pins 4-5 of the wiring strip) or normally closed (pins 3-4 of the wiring strip), whether to use one set of switches or two sets of switches, should be based on the actual alarms such as on-site PLC, DCS or audible and visual alarms. It depends on the condition of the equipment or control equipment. In most cases, a set of normally closed switches is used. A simple judgment method is to first check the Low and High toggle switch positions of the material level switch. When detecting low material level, the switch should be toggled to Low; when detecting high material level, the switch should be toggled to High. At this time, if the output wiring is correct, the entire control equipment should be operating normally. If it is the opposite, the normally open or normally closed wiring strip contacts need to be adjusted.

Figure 2 Two-wire output mode wiring diagram

2. Wiring method of material level switch in two-wire output mode

. Figure 2 is the wiring diagram of Tube-11 and Fork-11 in two-wire output mode. The two-wire wiring method is relatively simple. The two-wire interface of PLC or DCS generally has a 24V power output. The two-wire output material level switch can only be DC, not AC, and the power supply voltage range should be 10~36VDC. To ensure that the instrument works properly. The positive pole of the power supply is connected to pin 1 of the instrument wiring strip, and the negative pole is connected to pin 2 of the instrument wiring strip. It can work when powered on. The positive and negative poles of the power cord are also signal output lines, which are output in the form of current. 8mA indicates normal mode (low material level). There is material, high material level has no material) and 16mA alarm mode (low material level has no material, high material level has material), the internal circuit of the PLC or DCS input port (also the power supply port) can identify this signal.