The correct answer is: C. Both (A) and (B)
A thermocouple is a device that converts heat into an electrical signal. It is made up of two dissimilar metals that are joined together at one end. When the temperature at the junction changes, an electric current is generated. Thermocouples are used in a variety of applications, including temperature measurement, control, and protection.
An electronic relay is an electromechanical device that uses an electromagnet to control a switch. When the electromagnet is energized, it attracts a metal armature, which closes the switch. When the electromagnet is de-energized, the armature springs back to its original position, opening the switch. Electronic relays are used in a variety of applications, including switching power supplies, motor control, and alarm systems.
A bimetallic relay is a type of relay that uses two metals with different coefficients of thermal expansion. When the relay is energized, the two metals expand at different rates, which causes the bimetallic strip to bend. When the bimetallic strip bends enough, it closes the switch. When the relay is de-energized, the two metals contract at different rates, which causes the bimetallic strip to straighten. When the bimetallic strip straightens, it opens the switch. Bimetallic relays are used in a variety of applications, including overcurrent protection, overload protection, and temperature control.
To protect most of the electrical equipment handling low power, the types of relays used are electronic and bimetallic relays. Electronic relays are more accurate and reliable than bimetallic relays, but they are also more expensive. Bimetallic relays are less accurate and reliable than electronic relays, but they are also less expensive. The type of relay that is used depends on the specific application.