relays and solenoids

SPST RELAY

REFERS TO SINGLE POLE SINGLE THROW RELAY. THE SINGLE POLE MEANS THAT IT CAN CONTROL ONLY ONE CIRCUIT WHILE THE SINGLE THROW MEANS ITS POLE HAS ONLY ONE POSITION IN WHICH IT CAN CONDUCT.

DPST Relay

refers to double pole single throw

DPDT Relay

refers to double pole double throw

EMR (Electromechanical Relay)

This type of relay has an electromagnetic coil and a mechanical movable contact. When the coil is energized it produces a magnetic field. This magnetic field attracts the armature (movable contact). When the coil is de-energized the coil loose magnetic field and a spring retract the armature to its normal position

SSR (Solid State Relay)

operates on relatively high speed and has very low power consumption as compared to EMR relay.

Reed Relay

is made up of two metal blades made up of ferromagnetic material hermetically sealed in a glass tube which also supports the metal blades.

Electrothermal Relay (Thermal Relay)

is made up of bimetallic (made up of two metals having different thermal expansion coefficients) strip.

RELAYS

Their name reveals an essential part of how they function - like a runner in a relay race, they'll receive an electrical signal and carry it forward until handing it off to another component or relay.

TELEGRAPHS.

ELECTRICAL RELAYS GOT THEIR START IN APPLICATION TO

SCIENTIST JOSEPH HENRY

IS OFTEN CITED TO HAVE INVENTED A RELAY IN 1835 IN ORDER TO IMPROVE HIS VERSION OF THE ELECTRICAL TELEGRAPH, DEVELOPED EARLIER IN 1831

FUNCTION

They commonly use an electromagnet (coil) to operate their internal mechanical switching mechanism (contacts).

SPDT Relay

refers to single pole double throw relay