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How diodes protect the circuit from back emf which is generated by relay coils?
Wiki User
∙ 12y ago
The relay coil is an inductor and, as such, resists a change in current. When you de-energize the coil, it attempts to maintain the current flow, but it cannot because you have opened the circuit. This causes a high voltage spike to be developed across the coil which is of opposite polarity to the normal current. The diode conducts, dissipating the current and preventing the voltage from exceeding the safe operating voltage of the driving circuit, often a transistor.
The Diode is wired so that it is in reverse during normal operation, so no current passes through the diode and does not affect the coil it is parallel connected to.
Wiki User
∙ 12y ago
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What is a sweep generator?
A sweep generator is an instrument used to align IF circuits in older FM radios that used adjustable IF coils in the circuits. The generator "sweeps" the frequencies on either side of a set center frequency. When this signal is applied to the front end of an IF circuit, the responce from the IF circuit can be observed at the end of the IF with an oscilloscope allowing the IF coils in the circuit to be adjusted to the desired bandwidth and responce of the circuit.
Can back EMF be greater than battery EMF?
Yes. Let's look at an example. A 12 volt system can operate a 12 volt relay coil to actuate the plunger. But when the field of the coil collapses in the instant following when the coil is de-energized, the collapsing field can generate an "inductive kick" that can easily reach several hundred volts. Relay coils frequently have diodes across their coils to shunt this voltage through the coil and prevent it reaching other parts of the circuit because it is a higher voltage and could damage components. As a closing note, you're not "getting something for nothing" or generating more energy out of the coil than originally went in. The power in still equals the power out (less any loss). With a properly designed coil utilizing Marko Rodin's configuration, losses are negligible.
What is field coils?
field coils generally refer to the electromagnetic coils on the stator ( the stationary part of an electric motor ). these generate the magnetic field(s) necessary to put the rotor ( the rotating part of the motor ) into motion.
What song do they play in the Sorcerer's Apprentice with the Tesla coils?
Secrets by OneRepublic
Why to use centre tapped transformer in bridge wave rectifier?
In a rectifier, a center-tapped transformer and two diodes can form a full-wave rectifier that allows both half-cycles of the AC waveform to contribute to the direct current, making it smoother than a half-wave rectifier. This form of circuit saves on rectifier diodes compared to a diode bridge, but has poorer utilization of the transformer windings.
What is DC reactor in inverter?
This is used to improve the input power factor of the inverter power supply and reduce harmonics. The ''DC reactor'' is more effective than the input reactor in improving the power factorDC reactors (link chokes) are connected after the input diodes in the power circuit. One of the disadvantage of the DC reactors is they are located after the input diodes, and do not protect the diodes from possible voltage transients. One coil is needed in a DC circuit versus 3 coils in the AC circuit. Additionally DC reactors smoothing the current flow limits the high peak current pulses from abusing the capacitor bank inside the converter.
How many coils in air circuit breaker?
There are three coils in Air circuit breaker.. 1.Solonoid coil 2.Moving coil 3. fixed coil
What is the different between 3phase plus N generator coil and motor coil?
Generator coils generate the voltage, motor coils use the generated voltage.
Does a central air conditioning system have heat transfer coils?
The heat transfer coils are in the outside unit where the compressor and fan are to dissipate the heat generated and removed from the inside air.
What are the construction details of a brushless alternator?
A brushless alternator assembly will have the following major components. These include the case, stator, diodes, bearings, shaft, regulator and coils.
Is electricity generated by rotating magnets around copper coils AC or DC?
It is AC, alternating current. To create DC the generated power needs to go through a full wave rectifier.
What is a sweep generator?
A sweep generator is an instrument used to align IF circuits in older FM radios that used adjustable IF coils in the circuits. The generator "sweeps" the frequencies on either side of a set center frequency. When this signal is applied to the front end of an IF circuit, the responce from the IF circuit can be observed at the end of the IF with an oscilloscope allowing the IF coils in the circuit to be adjusted to the desired bandwidth and responce of the circuit.
Why wire in the coils of electromagnets must be isolated?
Presumably you mean 'insulated', rather than 'isolated'? In which case it is rather obvious, isn't it? If the coils weren't insulated, then the individual windings would short-circuit, and the coil itself would short circuit with the core of the electromagnet.
How is solenoid a magnet?
A Solenoid is an electro-magnet. It has coils of wire, usually copper. When an electric field is applied to the coils of wire, an magnetic field is generated. This magnetic field attracts a steel or iron segment on the switch and activates the switch.
What happen if you apply triangular input to transformer?
there will be no neutral point in the circuit and high voltage will be across the transformer coils
Summary of the step-down transformer?
A step- down transformer is one whose secondary voltage is less than its primary voltage, it is used to reduce 'step down' the voltage applied to it. The number of coils in the primary circuit is greater that the secondary circuit. For instance, to step down 480 Voltage to 240 voltage, you need a step down transformer whose ratio of primary coils to secondary coils is 2:1.
Why does an electrical breaker trip when you use a lot of appliances in the house?
since circuit breaker consists of coils they get heated up when high current flows, when this happens the coil get energised and pull the moving contacts to open thus the circuit breaker opens when high current flows.
