The composition of the power relay and its control function 2

From here, we can clearly see that because the electromagnetic power relay adopts such a working principle and structure, when it controls the production process in a certain way, it can realize the control that is difficult to achieve by manually switching electrical appliances (such as knife switches). function to meet more and more complex control requirements put forward in the production process. E.g

(1) Since it replaces manpower with electromagnetic suction, it can switch circuits quickly and effectively, ensuring the reliability of work; it does not require people to directly operate the controlled object, ensuring the safety of the operator; It is not limited by human physical strength, and greatly improves the operation frequency (the number of operations per unit time), which is conducive to shortening the work cycle of the controlled object and improving production efficiency.

(2), because it uses the iron core coil to receive the signal, it can realize long-distance control, can use a small input loop power to control a large output loop power, can use the signal reflected in the production process to control the production process In itself, it provides the conditions for the automation of the production process.

(3) Since it can use multiple docking points, it can realize centralized control, multi-point control and interlocking control of multiple objects.

All of these, from knife switches topower relays, from manual appliances to automatic appliances, are a major change and a qualitative leap in the field of electrical appliances. With the development of production, the scale of production is becoming larger and larger, the process is becoming more and more complex, more and more signals are required to respond, and various controls are required to be more and more complex, so various power relays and other automatic electrical appliances are corresponding produced. For example, people make appropriate changes to the core coil parameters of the electromagnetic power relay to form an electromagnetic voltage or current power relay that can respond to signals such as voltage or current. Figure 1-4 shows an example of a voltage power relay used for overvoltage protection. Here, the coil of the power relay is connected in parallel to the output end of a certain power supply device, and the voltage required for its action has been designed and adjusted by us in advance to be exactly equal to a certain voltage value. In this way, when the output voltage of the power supply equipment is equal to or exceeds ·, the power relay will act, the normally closed contact will be opened, and at the same time, another electromagnetic electrical appliance will be connected to a contactor (this is an electrical appliance with strong switching circuit capability. The electromagnetic power relay is the same) cut off, so as to cut off the user and the power supply equipment, so as to protect the user from excessive voltage damage. If the user requires that the current of the power supply equipment cannot exceed a certain specified value I, we can use a current power relay for protection, as shown in Figure 1-5. At this time, the power relay coil is connected in series in the user circuit, and only operates under the specified current I. Obviously, if these two power relays are used at the same time (one in parallel, one in series), they can protect the voltage and current to the user at the same time.