A 10A relay is connected to the supply circuit through 1000/ 10 A c.t and it is set at 50 % if the fauth current of the system is 5000 A , then Psm ?
Answers
Answer:
Basically, a relay is an electrically operated, remotely controlled switch. A simple electromagnetic relay is an adaptation of an electromagnet. It consists of a coil of wire surrounding a soft iron core, an iron yoke, which provides a low reluctance path for magnetic flux, a movable iron armature, and a set, or sets, of contacts. The armature is hinged to the yoke and mechanically linked to a moving contact or contacts. It is held in place by a spring so that when the relay is de-energized there is an air gap in the magnetic circuit. When an electric current is passed through the coil, the resulting magnetic field attracts the armature, and the consequent movement of the movable contact or contacts either makes or breaks a connection with a fixed contact. If the set of contacts was closed when the relay was deenergized, then the movement opens the contacts and breaks the connection, and vice versa if the contacts were open. When the current to the coil is switched off, the armature is returned by a force, approximately half as strong as the magnetic force, to its relaxed position. When energizing the coil of a relay, polarity of the coil does not matter unless there is a diode across the coil. If a diode is not present, you may attach positive voltage to either terminal of the coil and negative voltage to the other, otherwise you must connect positive to the side of the coil that the cathode side (side with stripe) of the diode is connected and negative to side of the coil that the anode side of the diode is connected. Diodes are not common in motorcycle applications.
Explanation:
It is always the case that once a relay has closed, it needs far less current to hold it closed than it took to close it. Often it will tolerate a drop to 25% of the nominal closing current before it drops out. You would need to experiment to find out what yours will do. The trick is to drive the relay coil through a parallel RC combination. The capacitor gets the nominal switching voltage to the relay, for long enough to close it. The resistor is sized to continue to conduct just enough current to hold it closed. After operation, the capacitor has to discharge through the resistor, so there is an upper limit to how fast the relay can be switched like this.