Electrodynamic Relay

-KOYAL

Relays are the devices which detect the abnormal conditions!!

Basic Definition

Electromagnetic Relays (EMRs)◦ EMRs consist of an input coil that's wound to

accept a particular voltage signal, plus a set of one or more contacts that rely on an armature (or lever) activated by the energized coil to open or close an electrical circuit.

Solid-state Relays (SSRs)◦ SSRs use semiconductor output instead of

mechanical contacts to switch the circuit. The output device is optically-coupled to an LED light source inside the relay. The relay is turned on by energizing this LED, usually with low-voltage DC power.

Microprocessor Based Relays◦ Use microprocessor for switching mechanism.

Commonly used in power system monitoring and protection.

Relay Types-

Construction

Working

Electrodynamic Relay

Balanced beam RelayAttached Armature type relay

Attached Armature type Relay

Balanced Beam Relay

Electromagnetic Relays (EMRs)◦ Simplicity◦ Not expensive◦ Mechanical Wear

Solid-state Relays (SSRs)◦ No Mechanical movements◦ Faster than EMR◦ No sparking between contacts

Microprocessor-based Relay◦ Much higher precision and more reliable and durable. ◦ Improve the reliability and power quality of electrical

power systems before, during and after faults occur.◦ Capable of both digital and analog I/O.◦ Higher cost

Advantages/Disadvantages

Relays control output circuits of a much higher power.

Safety is increased Protective relays are essential for

keeping faults in the system isolated and keep equipment from being damaged.

Conclusion