How Relays Work

The video tutorial explains the function and types of relays, including electromechanical and solid-state relays. It covers the components of relay circuits, such as the primary and secondary sides, and discusses normally open and closed relays. The tutorial also explores solid-state relays, their operation using semiconductors, and various applications of relays in controlling devices like fans and pumps. Advanced relay types, such as latching and double pole relays, are introduced, along with the concept of back EMF and the use of diodes for circuit protection.

What is the primary function of a relay in an electrical circuit?

• To decrease the current

• To control a circuit using a low power signal

• To convert AC to DC

• To increase the voltage

In a normally open relay, what happens when the primary circuit is energized?

• The load is turned off

• The primary circuit is disconnected

• The secondary circuit is completed and the load is powered

• The secondary circuit remains open

How do solid-state relays differ from electromechanical relays?

• They have moving parts

• They use solid-state semiconductors and have no moving parts

• They use an electromagnet

• They require more power to operate

What is the role of the LED in a solid-state relay?

• To generate a magnetic field

• To act as a switch

• To provide electrical coupling

• To provide optical coupling by emitting light

What happens when the LED in a solid-state relay is turned off?

• The primary circuit is energized

• The phototransistor continues to conduct

• The secondary circuit remains active

• The current in the secondary side stops

What is a latching relay used for?

• To provide optical isolation

• To convert AC to DC

• To increase the current in the circuit

• To maintain the state of the secondary circuit after the primary circuit is de-energized

What does the term 'pole' refer to in the context of relays?

• The number of contacts switched when the relay is energized

• The physical size of the relay

• The number of circuits a relay can control

• The voltage rating of the relay

What is a double throw relay also known as?

• A solid-state relay

• A latching relay

• A changeover relay

• A single pole relay

What is the purpose of using a diode in a relay circuit?

• To increase the voltage

• To suppress back EMF and protect the circuit

• To convert AC to DC

• To decrease the current

What is back EMF and why is it a concern in relay circuits?

• It is a forward voltage that stabilizes the circuit

• It is a reverse voltage that can cause voltage spikes and damage the circuit

• It is a type of current that increases efficiency

• It is a magnetic field that enhances relay operation