Relays And Controls 030104f Flashcards
What three components are part of a control circuit?
Objective 1 Page 2
Supply Component (Power Supply 24V)
Control Component (Switch Mechanism)
Load Component (Device The Circuit Is Operating. Consumes Power. Relay Coil)
What is an initiating device?
Objective 1 Page 2
Is a control component that controls the load. (Manual switch, momentary push button, multi-position switch, or automatic switches like temperature, pressure or flow)
What are some applications of solenoids?
Objective 1 Page 3
Signaling devices.
Pressure relief valve actuators.
Motor brake actuators.
Door lock and door holders.
Actuators for fire control devices.
Motion sensing actuators.
Control of gas and water valves.
What is known as the centering effect of the magnetic field?
Objective 1 Page 3
When a temporary magnet tries to centre itself in the middle of a magnetic field.
Example - Metal plunger in a solenoid when the coil is energized.
What is a relay?
Objective 1 Page 4
An automatic or remote control device that uses one or more initiating devices to control another device in the same or different circuit.
What are the six parts of a relay?
Objective 2 Page 6
Relay Coil (Conductor formed into loops. Electromagnetic field is created when a current flows through it)
Relay Core (Made of a magnetic material. Magnetized from the polarity of the field created by the coil)
Return Spring (Returns the armature back to normal position)
Armature (A movable metal strip that is used to operate the moveable contacts connected to it)
Normally Open Contacts (Set of contacts that are in the open position when the coil is not energized)
Normally Closed Contacts (Set of contacts that are in the closed position when the coil is not energized)
When is an electric circuit said to be supervised?
Objective 5 Page 17
When it is continually being monitored by a current flowing through it.
“Holding Contacts” are a set of:
Objective 5 Page 16
Normally open contacts that provide a path for current to the coil which operates them.
A relay is energized when there is voltage across what?
The coil
What are the basic components of the power circuit?
Objective 3 Page 8
Supply Component (120V Power Source)
Control Component (Relay Armature and normally open contacts)
Load Component (Lamp)
