Relays and Controls Flashcards
What is one application of solenoids?
- Signalling devices such as doorbell chimes
- Pressure relief valve actuators
- Motor brake actuators
- Door locks and holders
- Fire control device actuators
- Motion sensing actuators
- Control of gas and water valves.
What is an initiating device?
A control component of a circuit which controls a load by changing connections in a circuit.
What is a relay?
Essentially an electromagnet (actuated by an initiating device) which controls a separate power circuit. (A remote control device)
What is the load component of a control circuit?
A device which consumes power.
Concerning relays, what are two different types of circuit?
- Power circuit
- Control circuit.
What are three components in a basic control circuit?
- Supply component
- Control component
- Load component.
What are six basic components of a relay?
- Relay coil
- Magnetic core
- Return spring
- Armature
- Normally open contacts
- Normally closed contacts.
What are holding contacts?
Contacts which allow the relay which controls them to remain energized.
How are pull in voltage and drop out voltage described?
Pull in voltage allows the coil to overcome the return spring force, whereas drop out voltage is the threshold where the return spring force overcomes the electromagnetic force apply ed by the coil. Typically 75% and 50% of the relay’s rated voltage respectively.
What is a supervised circuit?
Any control / power circuit which has a current flow through either the control or power circuit at any one time, in its normal operation.
