This document is a project report on relays by Sheshadri Shekhar Rauth for his Bachelor of Technology degree in Electrical Engineering. It discusses the history and holding capacity of Diesel Loco Shed in Kharagpur, the basic design and operation of relays, and the types of relays used in the shed including wheel slip relays, general purpose relays, and contactor relays. It also provides references and concludes that the training opportunities at the shed were helpful for gaining knowledge about machinery and instruments.

2. A PROJECT ON
RELAYS

3. Project maid by
SHESHADRI SHEKHAR RAUTH
BACHELOR OF TECHNOLOGY
IN
ELECTRICAL ENGINEERING
NARULA INSTITUTE OF TECHNOLOGY
WEST BENGAL

4. Acknowledgement
I take this opportunity to express my sincere gratitude to all who have
helped me in the successful completion of my vocational training and
this project report. I would like to say my greatest appreciation to the
highly efficient and devoted technical staff, supervisors of the DIESEL
LOCO SHED, KHARAGPUR.I am highly indebted to them for their
tremendous support and help during the completion of my training
and project report.
Sheshadri Shekhar Rauth

5. Contents
History of Diesel Loco Shed
Relays
Basic design and operation
Type of relays used in DLS
Wheel Slip relay
General purpose relay
Contactor relay
References links
Conclusion

6. History of Diesel Loco Shed
 RAILWAY: SOUTH EASTERN RAILWAY
 SHED : DIESEL LOCO SHED,
 KHARAGPUR
 I. Brief History
 1. Year of Establishment: 1986.
 2. Road No / Type of the first loco homed in
 Shed: WDM1
 3. Details of any heritage Locos in Shed on pedestal or
otherwise: NIL
 5. Type Wise Holding (as on 01-06-10): WDM 2 48
 WDM3A:35 WDG3A:5 WDS6: DEMU 1400 HP DPCs: 07

7. 6. Homing Capacity: 100 locomotives

8. Relay
A relay is an
electrically operated
switch. Many relays
use an electromagnet
to operate a switching
mechanism
mechanically, but
other operating
principles are also
used. The first relays
were used in long
distance telegraph
circuits.

9. Basic design and
operation
When voltage is supplied to
the primary circuit, current
flows through the coil winding
to ground. Whilst doing so, a
magnetic field develops
around the primary coil. As
the magnetic field builds, it
pulls together the switch
contact in the secondary
circuit, thus supplying current
to the component being
operated.
When the relay is switched off
the magnetic field is removed
and the sprung plate returns
the switch to the open circuit
position, thus switching off
the power.
Schematic
symbol for the relay
Switching
contact
(
nail)
Armature contact
Electro
magnet AA cell 1.5 v
Switch
The
controlled
device in this
schematic is
a 6 – 9 volt
light bulb.
You can use
a DC motor
or other
device.
- +

10. Types used in DLS
Wheel Slip relay
A Wheel Slip relay has four
terminals. Two of those are
use in series operation and
another two are used in
parallel operation. At the
starting time out of six
traction motor each two
are connected in series and
those all three
constructions are
connected in parallel with
a resistor. In between one
pair of motors the wheel
slip relay is connected in
the equi-potential position.

11.  General Purpose relay
(GP)
 This type of relays is generally
used in loco. It has a magnetic
coil. It is magnetized for
tripping. It is a substance that
can make or break more than
one circuit at a time.The rating
of the magnetic coil is 74 v dc,
450 ohm at 20 degree C. The
contact of the relay is normally
closed. By energizing the
magnetic coil the contact can
be open. At a time more than
one circuit can be operated
through this relay.

12. Contactor relay
Such devices are
often used for
motor starters. A
motor starter is a
contactor with
overload
protection
devices attached.

13. References links
www.kpsec.com
www.autoshop101.com
www.oenindia.com
www.nteinc.com
www.teledynerelays.com
www.circuitstoday.com
www.embed4u.com
www.electrical4u.com etc.

14. Conclusion
 Training opportunities and facilities provided to us were
adequate and helpful. Each and every department of this
organization has given us full cooperation. All the
instructors journey in the reputed organization.
 During my training period, I have gained adequate and
valuable knowledge regarding various machineries and
instruments used in DLS(kgp). I hope that whatever
valuable knowledge and experiences I have gained during
this period, will be useful and helpful in my future
professional career.