Hot metal detectors are mainly used in metallurgical industrial systems. They detect red-hot high-temperature workpieces, determine the movement position of the workpieces, and output a control switch signal.

It has the following features: (1) It can work in harsh environments (such as high temperature, humidity, water mist, dust, etc.). (2) It can work reliably and continuously for a long time. (3) This detector integrates power supply, controller and output, and is easy to install.

■ Field of view:

When the detector is installed on site, the distance can be set according to the field of view and the type of material, and it can be aligned by visual inspection.

HMD hot metal detectors all have a certain field of view. For any type of HMD, it should be ensured that the moving range of the object being tested is within the field of view of the HMD.

The reference table of HMD detection field of view and setting distance is shown in the figure below. If there are special requirements for the field of view, it can be customized.

■ Light bar:

In order to make the HMD suitable for working in various conditions, it is equipped with four types of light barriers (Φ2, Φ4, Φ8, Φ16) that can be used to change the size of the field of view.

■ Cooling interface:

The cooling interface is used to pass cooling water. When the ambient temperature at the detector installation location reaches above 70°C, water cooling is required with a water pressure of 0.3MPa.

■ Purge interface:

When there is water vapor or smoke in the detector field of view, the detector sensitivity will be reduced, so please pay attention to it when setting it. To prevent this phenomenon, 0.3MPa compressed air should be added to the purge port of the dustproof cylinder.

■ Wiring:

a. Shielded cables should be used as much as possible for cables from the detector to the electrical room.

b. The cable connecting the detector to the control room should be within 200m and not too long.

c. Safety protection measures must be taken when the cable passes through a higher temperature area.

■ Level output:

The level output uses NPN/PNP transistor push-pull output, as shown in Figure 10, but only one load can be connected at the same time.

There are two types of loads allowed for level output: resistive load and inductive load. The maximum load current that can be provided is 100mA.

■ Contact output:

The cooling interface is used to pass cooling water. When the ambient temperature at the detector installation location reaches above 70℃, water cooling is required with a water pressure of 0.3MPa.

The output stage of the contact output is the contact of the relay. Pay attention to the use time. Do not let the load's maximum working current exceed the current allowed by the contact capacity, and the load power must not exceed the contact capacity.

There are two modes of contact operation: DC mode and AC mode. In both modes, there is no restriction on the nature of the load. Resistive load or inductive load can be connected, but the use of these two modes is slightly different. As shown in Figure 11, it is the wiring method of DC mode, and Figure 12 is the wiring method of AC mode.

When using in DC mode, for inductive loads, a freewheeling diode should be added as shown in the dotted line in Figure 10. The freewheeling diode should be selected as 0.5 A, more than three times the load voltage.

When working in AC mode, for inductive loads, R and C absorption circuits should be added as shown in Figure 12.