The internal structure and principle of common explosion-proof switch BZ-80, 120, 225

Figure 1 internal structural diagram of QBZ-80, 120, 225

Figure 2 Principles of QBZ-80, 120, 225

The above two pictures are the internal structure and electrical schematic diagram of QBZ-80, 120, and 225 switches. That is the contrast between the physical and the schematic diagram. The core component is a vacuum contactor. It plays the role of connecting and disconnecting the main circuit. Most of the components inside the switch work are to control the connection and disconnection of the contact of the vacuum contactor. Now, we analyze this circuit from Jane to Fan.

Figure 3

煤矿常用防爆开关BZ-80、120、225的内部结构及原理一

Let’s take a look at the two circuits above. On the left is a vacuum contactor to control a motor, and the right is a switch to control a light. The principle is the same: in the circuit on the right, the switch is closed and the lights are on. Disconten, the lights are extinguished. In the circuit on the left, the contacts of the contactor KM are closed, and the motor must be rotated electrically. The contactor is broken, and the electric motor stops to rotate. We all know that the switch in the right electric lamp circuit is controlled by manual. So how does the vacuum contactor on the left work? Look at the figure below:

煤矿常用防爆开关BZ-80、120、225的内部结构及原理一

Figure 4

煤矿常用防爆开关BZ-80、120、225的内部结构及原理一

Figure 5 Vacuum contactor structure diagram

The white box in Figure 4, he represents the coil of a vacuum contactor. The coil is essentially an electromagnet, which is powered on the electromagnet. The electromagnet generates magnetic force, so that the armed movement on the vacuum contactor is driven, thereby driving the contact movement in the vacuum tube (see Figure 5). Now, the question points to how to power the electromagnet coil.

煤矿常用防爆开关BZ-80、120、225的内部结构及原理一

Figure 6

Figure 7 QBZ-80 switch button structure diagram

Figure 6 is a simple answer to the simplest answer to the vacuum contactor inhalation. As long as the button SB1 is pressed, the vacuum contactor will be sucked. But the buttons used in the QBZ-80 switch are not like the switch of the home control light. When you press the button in the QBZ-80 switch, you can connect the button. As long as you let it go, the button is disconnected again (see Figure 7). So how can the contactor be sucked for a long time?

煤矿常用防爆开关BZ-80、120、225的内部结构及原理一

Figure 8

The principle Figure 8 solves this problem well. Compared to find out, there is a pair of contact KM in Figure 8. This pair of contacts are the auxiliary contacts in Figure 5. When the button SB1 is pressed, the coil is electrified. While driving the closure of the contact in the vacuum tube, the descendant also drives the frequent opening of KM in the auxiliary contact. This is, even if you release the button, because the auxiliary contacts are closed, the coil will be provided to the coil, and the coil will remain inhalation. At this time, the route flowing through the current is shown in the arrows of the middle of Figure 9.

煤矿常用防爆开关BZ-80、120、225的内部结构及原理一

Figure 9

煤矿常用防爆开关BZ-80、120、225的内部结构及原理一

The schematic diagram in Figure 8 solves the problem of combining coils after the button is loosened. But have you ever thought, now after the coil is sucked, we can maintain it. How should we stop it? Let’s talk about the next post.