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A electrical relay device is usually a small electro-mechanical switch which, when energized, will close a contact-set to complete another circuit.
A relay is used regularly by people who drive motor vehicles: the key switch (ignition switch) is turned to "Start" and 12 volts (approximately) is applied to the "starter solenoid" (which is actually a big relay). The solenoid's coil is energized - drawing only one to five amps or so from the battery - and it closes its high-current-carrying contacts so that the battery voltage is delivered to the starter motor, which usually draws around 100 amps or more...
If you didn't have that starter solenoid to do the job for you, to turn on that kind of current using only your ignition key you'd have to turn a very large key to turn a very big, heavy - and ugly! - switch on your steering column...
There are variations on this theme to which the term "relay" can be applied, but the idea remains the same: a small switch of some kind controls another (usually higher voltage and/or current) circuit.
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A relay is a switch as the previous contributor described; however, it does not necessarily control a higher voltage circuit. Relays are also commonly used in low power applications to switch a signal to one or more circuits. The common terminal of a relay is typically used as the input, and the throw describes the number of switches that are connected ("thrown") at the same time.
A relay is controlled by a solenoid. When the proper voltage is applied across the solenoid, the relay energizes, which activates the throw and the common terminals are connected to the Normally Closed (N/C) terminals. When no voltage is applied across the solenoid, the relay is unenergized and the common terminals are connected to the Normally Open (N/O) terminals of the relay.
Some common relays are:
SPST: Single pole single throw - has a single common and single output. The unenergized position is N/O because the signal at the common terminal is not present at the output until the relay is energized. Once the relay is energized, the input signal at the common terminal is connected to the output at the N/C terminal. This type of relay is used to connect a single common terminal to a single output terminal.
SPDT: Single pole double throw - has a single common and two outputs. In the unenergized position, the common terminal is connected to the N/O terminal. Once the relay is energized, the signal at the common terminal is connected to the N/C terminal. This type of relay is used to connect a single common terminal to one of two output terminals.
DPST: Double pole single throw - has two common inputs and two outputs. This type of relay is electrically equivalent to two SPST relays that operate simultaneously. In the unenergized state, the two common terminals (C1 and C2) are not present at either output terminal. In the energized state, C1 and C2 are switched to their respective output terminal at the same time.
DPDT: Double pole double throw - has two common inputs and four outputs. This type of relay is electrically equivalent to two SPDT relays that operate simultaneously. In the unenergized state, the two common terminals (C1 and C2) are present at the NO terminals (NO1 and NO2) of the relay. When the relay is energized, C1 and C2 are switched to the N/C terminals (NC1 and NC2) at the same time.
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What do relay and circuit breakers use?
No. A relay is an electric switch and a circuit breaker is an overcurrent device.
How can a relay be used to run a 9V electric motor?
A relay cannot be used to power a motor. It can be used to control the motor by wiring the motor circuit in series with the relay contacts.
What is the history of the electric circuit?
the history of the electric circuit is that the person who made it his name is jack kilby but the history is that the electric circuit was one of the easiest way was to make the electric circuit when the electricity went out. THE END
What is the function of a combination pliers in an electric circuit?
for made of electric circuit safety device,
What is the purpose of using transformer in electric bell circuit?
To supply the bell, because the latter has a rated voltage that's lower than the mains.
What is an electric circuit that controls another electric circuit through a relay?
Remote-Control Circuit. Any electrical circuit that controlsany other circuit through a relay or an equivalent device.
What do relay and circuit breakers use?
No. A relay is an electric switch and a circuit breaker is an overcurrent device.
Purpose of the indoor fan relay?
indoor fan relay An electric relay that starts and stops an indoor fan on cooling, electric - heating, and heat pump systems
What instrument measures current in an electric circuit?
That's the purpose of the "ammeter".
How do you find out what the bottom 3 fusses do on the kick plate of a 94 Toyota pick up?
one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay one is the circuit opening relay
How can a relay be used to run a 9V electric motor?
A relay cannot be used to power a motor. It can be used to control the motor by wiring the motor circuit in series with the relay contacts.
What is the marking 5A 250VAC24VDC on a relay means?
The switching circuit is 24 Volts DC which connects a circuit of 250 Volts AC with a limit of 5A current. Note: This is presumption based on how a relay works and its purpose.
Internal circuit of an electrical relay?
basic circuit of electrical protective relay
How an electrical relay works?
A relay will have a control circuit and a function circuitcould be the same feed line. One set of terminals (Hot and Load) can be activated at all times, but will not function until the control circuit is closed. The control circuit has a Hot and a Ground--when activated either by supply hot or ground by switch. The internal coil closes allowing the function circuit to operate. The purpose of this relay is to reduce the spike to the alternator. It takes less current (voltage) to close the coil on the relay than it would to operate the accessory that it controls
What does the relay do for the car?
There are three types of relay. Normally open relays mean the electric current can't pass until something causes the relay to close and complete the circuit. Example: when you start your car you are closinga relay when you turn the key and the circuit to the starter is allowing electricity to the starter. Normally close relays mean the circuit always has electricity unless you do something to stop it. Last but not least is a switching relay where the power is switched from one circuit to the next. Example: headlights bright to dim also dims or brightens the dash lights.
What causes a electric current in a electric circuit?
Voltage causes current to flow in an electric circuit.
The pathway taken by an electric current is a?
The term is "circuit" (from the same root as circle) An electric circuit must be uninterrupted for the current to flow. (This is why circuit-breakers are also called circuit-interruptors.)
