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Attracted Armature Type Induction Disc Type Induction Cup Type Moving Coil Type. Electromagnetic Relays. Hinged Attracted Armature Type relay. Shaded Pole Induction Disc Relay. Robust & reliable Construction Fluxes displaced in space & time Eddy currents in disc - PowerPoint PPT Presentation
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Electromagnetic Relays
• Attracted Armature Type
• Induction Disc Type
• Induction Cup Type
• Moving Coil Type
Hinged Attracted Armature Type relay
Shaded Pole Induction Disc Relay
•Robust & reliable Construction •Fluxes displaced in space & time •Eddy currents in disc•Disc rotation α driving toque•Brake magnet to avoid over run
• Used for over current protection• Used for slow speed relays• Reset/pick up ratio > 95%
Wattmetric type Induction Disc Relay
•Two electromagnets
• Upper and lower produce two different flux
• Energised by two different sources
•If energised by same source then R and X would be made different to get phased difference between fluxes
Induction Cup Relay
Induction Cup Relay
• Stationary core inside rotating cup
•Spindle carries arm - closes relay contacts
•Spring for resetting torque
•No brake magnet
•Principle of Induction motor
Induction Cup Relay
• Stationary core inside rotating cup
•Spindle carries arm - closes relay contacts
•Spring for resetting torque
•No brake magnet
•Principle of Induction motor
• Rotor is hollow cylinder (inverted cup)
•Two pairs of coils produce rotating field
•Cup has less inertia than disc
•Interaction of rotating flux with current
•Less magnetic leakage
•Torque per VA is 3 times than disc type
•Operating time 0.01 s
•High torque/inertia ratio
•Suitable for higher speeds of operation
•Used for distance & directional relays
Moving Coil Relay
Torque Production in Induction Relay
Torque Production in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay
Force Produced in Induction Relay