# How does a relay work? | Normally Open | Normally Closed | Steps towards learning Automation - 02

Practical Ninjas
Published at : 26 Dec 2020
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In this episode, we will see construction and working of relays and the different types of relays such as Normally Open and Normally Closed.

It's relatively easy for anyone with an understanding of relay-type control wiring to program PLCs with little guidance.

When current runs through the control circuit and energizes the coil, it creates a small magnetic field which pulls the arm of the switch towards the coil and completes the second circuit. Thus, the light glows. When the electromagnet is not energized, the spring pulls the armature away and the circuit is not complete. In that case, the light is off. These parts are safely held with the help of a spring.

Now, when you use relays, you have to decide whether it should work as normally open or normally closed or in short active high or active low respectively. Often they are referred to as examine if closed (XIC) and examine if open (XIO). Normally open or normally closed relays depend upon the configuration of armature.

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Link to the #1 video in the series: https://youtu.be/rFs0zwx_s9g
Introduction to PLC | Programmable logic controllers | Steps towards learning Automation - 01

Link to the #2 video in the series: https://youtu.be/fmEmvSazqq8
How does a relay work? | Normally Open | Normally Closed | Steps towards learning Automation - 02

Link to the #3 video in the series: https://youtu.be/6sQt1N0nBeE
Concept of Sinking and Sourcing in PLC | Steps towards learning Automation - 03

Link to the #4 video in the series: https://youtu.be/zsajTNtxfAE
PLC Ladder programming #1 | NO NC contacts | AND gate logic | Steps towards learning Automation - 04
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Link to the video on Derived gates:
https://youtu.be/wGilEPBfcT8

Link to our video on Boolean algebra
https://youtu.be/V4QRxFruzk8

Link to previous videos on Gates:
Basic gates https://youtu.be/-6w-MHjwzT0
Derived gates https://youtu.be/wGilEPBfcT8

Mathematical operations in digital systems
Multiplication and Division https://youtu.be/2lemxMYsJXU

Constructing gates
Using NAND https://youtu.be/okZBqPd1xd4
Using NOR https://youtu.be/auh8NRN0wR0
on Double Beam Spectrometer

on Basics of UV-Vis spectroscopy in Analytical Instrumentation

on Filters and Monochromators, Gratings used in Analytical Instrumentation

on Detectors used in Analytical Instrumentation:

on Single Beam Photometer used in Analytical Instrumentation

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Check our playlist on Analytical Instrumentation:
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Please watch: "What makes our phones smart? - SOC | System on Chip | Brain of a smartphone"
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