Relay's concept

What is relay

Hi friends Today, I will explain about switching relay, Electromagnetic relay, this is simple circuit of relay.

electrical relay

Relay has 2 electrical circuits,

1) input circuit

2) output circuit

Function of relay is, connect input circuit, with output circuit with isolation, Relay has one coil, this coil has 2 terminals, one is phase or (+) and second is neutral or (-).

NO NC contact concept in Hindi,electromagnetic relay in hindi

It has one contact also, contact has 3 terminals, common, 2nd NC and 3rd is NO, this contact,

Between COM and NC, is called NC or normally close contact, why normally close?, Because, If relay is OFF (normal condition), in that case, this contact will be close,

NO is called, normally open contact, If relay has no current, then this is open, So, it’s called NO.

If current flows in the input circuit, by closing switch, then current flows in the coil, then core becomes magnetized, due to magnetization, core attract the contact, Contact has metal portion also, so that metal of the contact, is attracted by magnet, then this switch will shift, switch position was here at NO, if current flow in coil, switch connection will be at NC,

If used DC source, source can be AC also, if coil is rated for DC, then DC is used, if coil is rated for AC, then AC is used, this DC or AC has no relation with contact.

Here, only 1 contact was shown, but relay may have multiple contacts, one input circuit and 2 outputs circuits, voltage can be different for all three circuits for example, if this DC, then this can be AC, here some other AC supply, or DC is also possible here, all 3 circuits are isolated with each other,

relay experiment in hindi ,electromechanical switch , electrically operated switch

Examples:

1) Here, one motor is connected, the switch is open, so circuit of motor is open, no current in motor, so motor will not run, if we close the switch, then, the contact will be at NC, because current flows in the coil, what will happen now ?, the motor circuit is complete, current will flow and motor will start rotation, when this switch was open, motor was OFF, if switch is closed, then motor will start, by using one small switch, we can control big size motor.

2) Here coil circuit is same like above, but DC source is connected, when switch is open, then no current in the coil, so NC contact will be close, then current flows , then this LED (L2) will glow, if we close the switch, then NO become NC and NC become NO, now what happens ? Then this LED(L1) will glow, 1st L2 was ON, as connection was at NC, after switch is ON, this L1 will glow.

Many types of relays are Available in market, some are small in size and some are big in size, rating of coils is different, contact rating are also different, coil of the relay is rated for 5 V, coil, 12 V, AC 220 V type.

This types of relays are use for low voltage switching purpose, to isolate the PLC output with load etc.

Thank you friends ,if you like my article so, please