A power relay is a device that can produce a jump in one or more electrical output circuits when the input (or excitation) meets certain conditions. It can be used as the directional element of zero sequence current protection in neutral point direct grounding system. It should be added here that there are many different brands of power relays in the market, andFinder power relayIt's a brand product. Next, let's take a look at the different principles of finder power relay.
The working principle of finder power relay is that when a certain voltage or current is applied to both ends of the power relay coil, the magnetic flux generated by the coil passes through the working air gap of iron core, yoke, armature and magnetic circuit. Under the action of the magnetic field, the armature is attracted to the polar surface of the iron core, thereby promoting the normally closed contact opening and normally open contact closing of the contact; When the voltage or current at both ends of the coil is less than a certain value and the mechanical reaction force is greater than the electromagnetic suction, the armature returns to the initial state, opens the normally open contact and connects the normally closed contact.
Contact principle of power relay
Finder power relay is a device that can be converted in one or more electrical output circuits when the input (or excitation) meets certain conditions. In the neutral point direct grounding system, it can be used as the directional element of zero sequence current protection. The action process of the contact can be divided into two parts: contact closing and contact breaking, that is, the pull in and release process of the relay. They switch circularly at a certain frequency, forming the phenomenon of contact opening and closing. In the process of contact closing and opening, there are many special physical and chemical phenomena, such as contact resistance, contact jitter and arc discharge.
Action principle when the contact is closed
When the dynamic contact and static contact of the relay are in contact with each other, contact rebound will occur, that is, uncontrolled gap opening and closing. At this time, the arc and Joule heat generated by the energized current will greatly affect the opening and closing ability of the relay.
Action principle when the contact is disconnected
When the contact is disconnected and the load is disconnected, dazzling sparks and arcs will be generated. The arc will not occur until the arc voltage drops below the minimum arc voltage value, which will cause serious damage to the contact. Different contact materials and contact gap size directly affect the radiation state of arc electrons and the difficulty of occurrence, which is an important condition to determine the arc function of power relay. Power relay has the advantages of fast action, stable operation, long service life, small size and so on. It is widely used in power protection, automation, motion, remote control, measurement and communication equipment.