17-04-2012, 01:30 PM
NUMERICAL RELAYS
Numerical Relay.ppt (Size: 156 KB / Downloads: 258)
RELAY TECHNOLOGY
ELECTROMECHANICAL RELAYS :
MECHANICAL FORCES CAUSES OPERATION OF RELAY CONTACT IN RESPONSE TO A SIGNAL.
CAN BE CLASSIFIED TO SEVERAL TYPES –
ATTRACTED ARMATURE
MOVING COIL
INDUCTION
THERMAL
ADVANTAGES OF NUMERICAL REALYS
FLEXIBILITY IN WIDE PARAMETER ADJUSTMENT.
PROGRAMMABLE FUNCTION SETTING
MULTIPLE FUNCTIONS BY THE SAME RELAY
INTERNAL FAULT DIAGNOSIS.
MEMORY & RECORDING FUNCTION
PROGRAMMABLE CT & PT RATIO
DIGITALLY COMMUNICATION FACILITY
DISADVANTAGES WITH NUMERICAL RELAYS
HIGH INITIAL COST
REQUIRES STABLE POWER SUPPLY.
IF USED FOR MULTIFUNCTION IN A SINGLE FEEDER, FAILURE OF RELAY MAY CAUSE TOTAL PROTECTION FAILURE FOR THE EQUIPMENT.
REQUIRES EMC ENVIRONMENT.
RELAY HARDWARE STRUCTURE
A/D CONVERTER:
CONVERTS TO DIGITAL SIGNALS FOR HANDLING IN MICROPROCESSOR.
MICROPROCESSOR :
DIGITAL SIGNAL HANDLED FOR ALGORITHMS & SCHEME LOGIC FUNCTION.
ROM : CONTAINS THE RELAYING PROGRAMME.
RAM :
USED FOR STORING SAMPLED QUANTITIES & INTERMEDIATE PRODUCTS IN RELAYING ALGORITHMS.
E2PROM :
USED FOR STORING RELAY SETTINGS.
CONCLUSION
NUMERICAL RELAYS NEED TO BE INCORPORATED IN THE DESIGN STAGE OF THE PLANT .WHICH WILL HELP TO
REDUCE THE PANEL SIZE.
PANEL WIRING COST.
POPULATION OF RELAYS IN THE PLANT.
MEET SPACE CONSTRAINTS.
REDUCE THE QUANTUM OF SPARES.