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Relays
1. RELAYS
By
Chetan Goyal
Work carried out at
Submitted to
Department of Electronics and Communication
Engineering
School of Engineering and Technology
Raffles University, Neemrana
3. Company profile
a).Introduction:
Minda Furukawa Electric Pvt. Ltd. is a joint
venture between the Spark Minda, Ashok Minda and
Furukawa of Japan. The joint venture is a 51:49
partnership .
The company develops and produces the entire range
of wiring harness for four wheelers for its customers,
and components related to wiring harness e.g.
couplers, terminals, relay, junction box etc.
The plant is located at Bawal, Haryana and has all the
state of the art machinery, testing and support
facilities for making all types of wiring harness as per
customer’s requirement.
4. b). Work culture
Along with producing world class
products, all activities are geared towards
innovation, reduction of costs and overheads
to increase profitability. In order to achieve
these lofty goals , Minda Furukawa believes
that the human element is very important .
Accordingly it places great emphasis on
promoting the best practices in work culture
and employee welfare .
Their motto is “We challenge Excellence
with Team spirit”.
6. d).Vision
Aimed at
undertake technical
innovation using modern
technology and skillsmanship.
“Quality first”, devoted to customer and grow
holistically towards future.
Focus on Quality
CF, CS, & CD
Customer first
Customer safety
Customer delight
Adopt new techniques.
7. Introduction to Relays
Relays are switches that open and close circuits
electromechanically or electronically. Relays control one
electrical circuit by opening and closing contacts in another
circuit. when a relay contact is normally open (NO), there is
an open contact when the relay is not energized. When a
relay contact is Normally Closed (NC), there is a closed
contact when the relay is not energized. In either
case, applying electrical current to the contacts will change
their state.
Relays consist of an electromagnet and also a set of contacts.
A relay is used when a circuit is to be controlled at a low
power signal. Relays are often grouped together or with other
components like fuses.
. Relays have two circuit: a control circuit and a load circuit.
8. Basic design or operation
A simple electromagnetic relay
consists of a coil of wire wrapped
around a soft iron core, an iron yoke
which provides a low reluctance
path for magnetic flux, a movable
iron armature, and one or more sets
of contacts. The armature is hinged
to the yoke and mechanically linked
to one or more sets of moving
contacts. It is held in place by a
spring so that when the relay is deenergized there is an air gap in the
magnetic circuit. In this
condition, one of the two sets of
contacts in the relay is closed, and
the other set is open.
9. Types of Relays
1.
2.
Basically, Relays are of two types either
electromechanical or solid state relays. Both accomplish
the same result but the physical structure and
functionality makes them different.
Electromechanical Relays(EMR) : In
electromechanical relays contacts are open or closed
by a magnetic force. Basic parts and functions of
electromechanical relays include:
Frame
Coil
Armature
Contacts
Solid State Relays(SSR): In solid state Relays there
are no contacts and switching is totally electronics. It
consist of
an input circuit
a control circuit
10. Parts of Relays
There are generally four parts in a
relay. These are
1. Electromagnet: An electromagnet is a
type of magnet which consist of
wrapping of copper coil around a soft
iron core in which magnetic field is
produced due to flow of current
through the coil.
2. Armature: A relays moving part. The
armature opens and closes the
contacts. An attached spring returns
the armature to its original position.
11. Continue…..
3.
4.
Contacts: The conducting part of
the switch that makes (closes) or
breaks (opens) a circuit. ‘Closed
state’ of contacts means
electricity can flow between
them, or ‘open state’ means
contacts are separated and the
switch is nonconducting.
Spring: Spring is attached to the
armature of the relay which helps
in returning the armature to its
original position.
12. Applications
Amplifying a digital signal, switching a large
amount of power with a small operating
power.
Detecting and isolating faults on transmission
and distribution lines by opening and closing
circuit breakers.
Isolating the controlling circuit from the
controlled circuit when the two are at different
potentials.
In logic functions.
Time delay functions.
Used to control high voltage circuits with the
help of low voltage signals.
13. Advantages of Relays
Used as a kind of safety switch to allow a
circuit with a small current through to switch
on a circuit that will have a larger current flow
through it.
Minimize the amount of damage to the
system during a fault.
Small control signal controls a larger load
current or voltage.
Decreased electrical noise when switching.
Totally silent operation.
Output resistance remains constant
regardless of amount of use.
14. History about Relays
The relay was invented in 1835 by
American scientist Joseph Henry in order
to improve his version of the electrical
telegraph.
A simple device, which we now call a
relay, was included in the original 1840
telegraph patent of Samuel Morse. The
mechanism described acted as a digital
amplifier, repeating the telegraph signal,
and thus allowing signals to be
propagated as far as desired. This
overcame the problem of limited range of
earlier telegraphy schemes.