60
F. Firouzi et al.
Finally, relays can also be categorized in the following manner [4, 5]:
• Electromechanical Relays (Armature Relays) – Electrical switches are made of
coils, contacts, and a moveable armature. These relays are mostly used to control
high-power electrical devices. An energized coil creates an electromagnetic field
which in turn it can open/close the circuit using physical movement of armature
contacts (see Fig. 2.4).
• Reed Relays – Switches comprised of overlapping ferromagnetic blades and coils
wrapped around reed switches. This type of relay utilizes mechanically actuated
physical contacts to open or close a circuit. However, Reed relay contacts are
smaller and have less mass than electromechanical relay contacts (see Fig. 2.5).
• Solid-State Relays – Light, commonly from an encapsulated LED, actuates a
photosensitive MOSFET enabling current to flow through (see Fig. 2.6).
Fig. 2.4 Electromechanical
relay (armature relay)
Contact
Contact
Coil
Ceramic enclosure
Open Reed Contact
Close Reed Contact
Fig. 2.5 Reed relay
F. Firouzi et al.
Finally, relays can also be categorized in the following manner [4, 5]:
• Electromechanical Relays (Armature Relays) – Electrical switches are made of
coils, contacts, and a moveable armature. These relays are mostly used to control
high-power electrical devices. An energized coil creates an electromagnetic field
which in turn it can open/close the circuit using physical movement of armature
contacts (see Fig. 2.4).
• Reed Relays – Switches comprised of overlapping ferromagnetic blades and coils
wrapped around reed switches. This type of relay utilizes mechanically actuated
physical contacts to open or close a circuit. However, Reed relay contacts are
smaller and have less mass than electromechanical relay contacts (see Fig. 2.5).
• Solid-State Relays – Light, commonly from an encapsulated LED, actuates a
photosensitive MOSFET enabling current to flow through (see Fig. 2.6).
Fig. 2.4 Electromechanical
relay (armature relay)
Contact
Contact
Coil
Ceramic enclosure
Open Reed Contact
Close Reed Contact
Fig. 2.5 Reed relay