This document provides an overview of the Mainline Electric Multiple Unit (MEMU) rail system in India. It describes key components of the MEMU including the pantograph that collects power from overhead wires, main transformers that step down voltages, rectifiers that convert AC to DC for traction motors, and auxiliary systems like lighting, compressors, and a battery. The summary highlights the purpose of the MEMU for semi-urban and rural passenger service and provides a high-level view of the electrical systems and components that power and control the trains.

1. Presentation on MEMU

2. Introduction
• The Mainline Electric Multiple Unit or MEMU
is a commuter rail system in India operated by the
Indian Railway for semi-urban and rural areas.
• MEMU trains are designed for semi-urban and
rural areas, unlike EMU trains that are designed
for urban and semi-urban areas. MEMU trains
also have end vestibules not found on EMU
trains. Also, unlike EMU, MEMU trains have
lavatories.

3. Block Diagram of MEMU

4. Pantograph (4.5-7.0 Kg/cm2)
• A pantograph is an
apparatus mounted on the
roof of MEMU to collect
power through contact with
an overhead catenary wire.
• It is a common type of
current collector.
• Typically, a single wire is
used, with the return
current running through the
track.

5. Current Transformer
• IT is used to measure
the value of current
coming from the
catenary wire.
• Its location is below the
VCB .

6. VCB (400A, 30KV)
• A circuit breaker is an
automatically operated
electrical switch designed to
protect an electrical circuit
from damage caused by
overload or short circuit.
• Its basic function is to
detect a fault condition and
interrupt current flow.
• Unlike a fuse, which
operates once and then
must be replaced, a circuit
breaker can be reset to
resume normal operation

7. Rod Gap LA (10 KA)
• A lightning arrester is a device
used to protect the insulation
and conductors of the system
from the damaging effects of
lighting.
• The typical lightning arrester
has a high voltage terminal
and a ground terminal.
• When a lightning surge travels
along the power line to the
arrester, the current from the
surge is diverted through the
arrestor, in most cases to
earth.
(i) Earthing is done for Short circuit as well as for lightning.
(ii) Earthing S/w is connected with VCB in order to prevent contact with 25kv supply during maintenance.

8. Main Transformer (1000 KVA)
• It is used to step-down
the incoming supply to
782V, 266V and 141V .
• 782V ------ Tap Changer
• 266V ------ Aux. Motors
• 141V ------ Light & Fan
• OFAF Cooling
Secondary
Ckt.
Aux.
Circuit

9. Tap Changer (1000V AC)
• A tap changer is a
connection point
selection mechanism
along a power
transformer winding that
allows a variable number
of turns to be selected in
discrete steps.
• No. Of Steps =22
• Shunt 1 to 2
• Half Power 3 to 12
• Full Power 13 to 22

10. Rectifier Unit
Main Rectifier Unit Auxiliary Rectifier Unit
• It is used to provide input
supply to DC Traction
Motors through Smoothing
reactor, ASL and MSG.
• It has Bridge Configuration
with 3000V (PIV) of Diodes.
• Force Air Cooled.
• It is used to provide input
supply to main compressor
and air drier. It is housed in
main rectifier cubical.
• It has Bridge Configuration
with 2000V (PIV) of Diodes.
• Force Air Cooled.

11. Rectifier Blower Fan

12. Smoothing Reactor
• It is a inductive filter used to remove the ac content
from the main rectifier output.
• OFAF cooling common with 1000KVA Main
Transformer.

13. ASL
• IT is used to remove the
left over AC content
called ripples present
in the electrical power
received from
smoothing reactor.

14. Traction Motors (535V, 1260rpm)
• Traction motor used in
MEMU is DC series
compound motor.
• No. of motors : 04
• Insulation :
Armature– class H
Field --- Class F
Suspension – Axle Hung

15. Auxiliaries
• Transformer oil pump
Rating : 240V , 1.5 h.p.
Capacity: 400 ltrs
No. of units: 01
It is used to pump the oil for
cooling purpose.
• Battery
50 lead acid cells each in 10
units
90Ah Rating
It gives supply to :
Auxiliary compressor
DC Emergency lights
Set of panels
Twin beam head light
LED based Tail Light
ESMON System
ESMON: Energy
saving
Monitoring
system
i
It is a Monitoring Device which keep
record of:
Speed
Distance
Time
Energy Consumed

16. Master Control
• The Master controller
remain activated
manually and
consciously by the
driver in case of the
driver gets
incapacitated and the
device is released , the
emergency brake shall
get applied.

17. LIGHTS AND FANS
FLASHER
LIGHT
TWIN BEAM
HEAD LIGHT
• TAIL LIGHT: 40W (2 Normal and 1 Emergency)
• TWIN BEAM HEAD LIGHT : 300W
• FANS: 65W
LED TAIL
LIGHT TWIN
MARKER
LIGHT

18. COMPRESSOR
MAIN
• 9.12 KW, 99A, 110V DC
• IT IS USED FOR SUPPLYING
AIR FOR ELECTRO-PNEUMATIC
BRAKES.
AUXILIARY
• 8.5KW, 110V DC
• PRESSURE 8Kg/cm2
• IT IS USED FOR LIFTING THE
Pantograph
STATIC BATTERY CHARGER
• Efficiency is 80% , Power factor is 0.8, used for battery
charging and is placed behind Driver’s Desk

19. Compressor Static Battery Charger

20. Relays
PRIMARY OVERLOAD RELAY
MOTOR OVERLOAD RELAY
NO VOLT RELAY
CURRENT LIMIT RELAY
OVER VOLTAGE RELAY
CONTROL GOVEROR RELAY
COMPRESSOR GOVERNOR RELAY
HT RELAY
CURRENT BALANCE RELAY
FOR RECTIFIER
EMERGENCY LIGHT RELAY
BUCHOLZ RELAY
RECTIFIER FAN RELAY
TRANSFORMER THERMOSTAT RELAY
BREAKER RESET RELAY
AIR BLAST RELAY
DEAD MAN RELAY

21. Inter Vehicular Coupler
No. Of Jumpers 04
with 19 cores
03- lights and Fans
01- Main Control

22. Bogie Motors control section

23. Smoke Detector
Twin DC DC Convertor for Head
Light

25. THANK YOU