17-10-2016, 04:14 PM
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introduction
In this presentation we are going to elaborate on the failures occurred in locomotive relays used in loco. We will also look at the reasons for these failures and what are possible and best procedures or techniques to reduce the failures of these relays and also to improve the performance of relays so that our loco faces the minimum cases of relay failures.
What a relay is ?
RELAY IS AN ELECTROMAGNITIC SWITCH DEVICE WHICH IS USED TO THE ELECTRIC INFORMATION FROM ONE CKT TO ANOTHER , THROUGH A SET OF CONTACTS.
IT IS A DEVICE WHICH DETECTS THE FAULT AND IS RESPONSIBLE TO ENERGIZE THE TRIP OF A CKT BREAKER.
Relays are the "tools" of the protection engineer. As in any craft, an intimate knowledge of the characteristics and capabilities of the available tools is essential to their most effective use.
TYPES OF RELAYS
AIR PRESSURE RELAYS
PROTECTION RELAYS
TIME LAG RELAYS
MFO RELAYS
AIR FLOW RELAYS
Classification of Relays
Current Operated (DI)
These relays operate over the current supplied to the relays and protects circuit from over current flow.
Some of current operated relays are:
QLM
QRSI
QE
QF
QLF
MCR
Voltage Operated (DU)
These relays protects circuit from the over voltage flowing across the circuit. They operate according to the supply voltage.
Some of the voltage operated relays are:
QOP
QOA
Q30
Failures of relay
Failures of Air Flow/Air Pressure Relay :
Breaches in mechanical part.
Electrical short circuits.
Wear and tear of rubber diaphragms.
Decreased tension in spring systems.