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When a capacitor is powered off in an energized circuit, the capacitor still stores a certain amount of electricity. When there are other loads or components in the circuit, they will slowly discharge, or they can be quickly discharged by short-circuiting with small resistors or wires (at low voltage).
When the capacitor discharges, the two poles of the capacitor respectively carry a certain amount of charge, and the outside world and the capacitor form a closed loop (generally, the closed loop does not include a power supply). The excess electrons (negative charges) approach the positive electrode of the capacitor to form a current, so that the charges at both ends of the capacitor are neutralized. When the neutralization is completed, the electric field between the two electrodes of the capacitor disappears. However, this is in an ideal situation. The amount of terminal charge is exponentially neutralized towards zero, but not zero.
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Discharge requirements of capacitors
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After the capacitor is disconnected from the bus, it must be discharged through a discharge resistor or a special voltage transformer.
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Discharge should be performed between the lead wires of the capacitor and between the lead wires and the casing.
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The capacitor can be grounded after the capacitor is discharged.
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Before working on the capacitor, be sure to conduct a test discharge. This discharge is to place the discharge rod on the terminal of the lead wire of the capacitor for a period of time.
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Even if both sides of the capacitor device are grounded, in order to prevent residual charge on the capacitor, a test discharge must be performed, and each group of capacitors connected in parallel must be discharged.
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Special care should be taken when conducting inspection discharge of capacitors removed due to faults. Due to the damaged capacitor, the general grounding device may not function as a ground discharge due to a partial disconnection.
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If the capacitor device has an interlock device, it should be considered that only after the entire device is grounded, the small door of the capacitor bank protective fence can be opened.
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jec888
Wiki User
∙ 14y agoA Bleed Resistor connecting to both ports on the capacitor
Wiki User
∙ 11y agoA capacitor can be discharged by connecting a resistor between the two capacitor leads. The voltage of the capacitor will discharge across the resistor and the capacitor will lose its charge.
Wiki User
∙ 13y agoBy connecting a load across its terminals, preferably not a small load for a large capacitor. A small cap on the other hand can usually be shorted to discharge it.
Wiki User
∙ 12y agoThrough a bleeder resistor.
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How a can capacitor smoothen or reduce the ripple of the voltage produce by the rectifier?
Rectifiers will not give a smooth DC voltage. There are ripples in the voltage given the rectifier. So in order to smoothen the voltage we use capacitor in parallel to the rectifier output. Now lets see how the capacitor smoothen the voltage that is coming from a rectifier...... Capacitor blocks DC and allows AC...... If we take the voltage that is coming from the rectifier it has some ripples in addition to DC, these ripples can be divided in to sinusoidal wave forms ( fictitious )according to the Fourier series. So the rippled DC now divided ( fictitious ) in to a pure DC and sinusoidal AC wave forms having the frequency that is multiples of ripple frequency. Now the DC current will not pass through the capacitor as the capacitor blocks DC. But the AC will pass through it i.e the ripple wave forms that are divided ( fictitious ) in to sinusoidal AC wave forms will pass through the capacitor. So only DC current enters in to the load, which will produce a pure DC voltage drop across the load. In this manner the capacitor smoothens the voltage.
Why does the ratio of the voltage to current in capacitor and inductor depend on frequence?
The ratio of voltage to current, or the impedance, of reactive elements such as capacitors and inductors depends on the frequency of the applied wave because they store energy, and the amount of energy they store is directly related to the frequency of the applied waveform. When a DC voltage is applied to a capacitor, the current through the capacitor initially will be large, and will decay down to zero as the capacitor charges. Also, the voltage across the capacitor will be small initially and will increase over time to be equal to the applied voltage. This behavior results in a varying impedance when an AC waveform is applied. At a very low frequency, the capacitor will charge up and discharge similarly to if a DC source was switched into the capacitor for a long period of time there would be a large voltage drop, and small current = high impedance). As the frequency increases, the capacitor will appear more like a DC source was initially switched into the capacitor (low voltage drop and high current = low impedance).
What observation is made when using a bigger value for a capacitor in a full wave bridge rectifier?
bigger capacitor value will make the discharge taking longer time and that is willmake the curve is closer to dc line which means the higher capacitor value will help to have a closer signal to the dc and reduce the ripple voltage
What happens to current flow in a capacitive when the DC voltage across the capacitor is approximately equal to the source voltage?
As long as you don't exceed the breakdown voltage of the capacitor ... which is marked right on it ... DC voltage on it produces NO current flow through it. Only AC 'appears' to flow through a capacitor, and even that appearance is bogus when you really get down to it.
What is the effect in output for changing input frequency in halfwave rectifier?
if filtered and loaded the average DC voltage will increase and the ripple AC voltage will decrease, but the peak voltage is unchanged. this is because the filter capacitor has less time to discharge into the load.if unfiltered or unloaded the voltage cannot change. unfiltered the waveform just follows the half cycle of the input. if filtered but unloaded the output is DC at the peak voltage of the input AC.
Will a capacitor lower voltage?
A: As soon as a DC voltage is applied the capacitor is a short or no voltage
Why does the ratio of the voltage to current in capacitor and inductor depend on frequence?
The ratio of voltage to current, or the impedance, of reactive elements such as capacitors and inductors depends on the frequency of the applied wave because they store energy, and the amount of energy they store is directly related to the frequency of the applied waveform. When a DC voltage is applied to a capacitor, the current through the capacitor initially will be large, and will decay down to zero as the capacitor charges. Also, the voltage across the capacitor will be small initially and will increase over time to be equal to the applied voltage. This behavior results in a varying impedance when an AC waveform is applied. At a very low frequency, the capacitor will charge up and discharge similarly to if a DC source was switched into the capacitor for a long period of time there would be a large voltage drop, and small current = high impedance). As the frequency increases, the capacitor will appear more like a DC source was initially switched into the capacitor (low voltage drop and high current = low impedance).
WHY does the ratio of the voltage to current in capacitor and inductor depend on frequency?
The ratio of voltage to current, or the impedance, of reactive elements such as capacitors and inductors depends on the frequency of the applied wave because they store energy, and the amount of energy they store is directly related to the frequency of the applied waveform. When a DC voltage is applied to a capacitor, the current through the capacitor initially will be large, and will decay down to zero as the capacitor charges. Also, the voltage across the capacitor will be small initially and will increase over time to be equal to the applied voltage. This behavior results in a varying impedance when an AC waveform is applied. At a very low frequency, the capacitor will charge up and discharge similarly to if a DC source was switched into the capacitor for a long period of time there would be a large voltage drop, and small current = high impedance). As the frequency increases, the capacitor will appear more like a DC source was initially switched into the capacitor (low voltage drop and high current = low impedance).
How a can capacitor smoothen or reduce the ripple of the voltage produce by the rectifier?
Rectifiers will not give a smooth DC voltage. There are ripples in the voltage given the rectifier. So in order to smoothen the voltage we use capacitor in parallel to the rectifier output. Now lets see how the capacitor smoothen the voltage that is coming from a rectifier...... Capacitor blocks DC and allows AC...... If we take the voltage that is coming from the rectifier it has some ripples in addition to DC, these ripples can be divided in to sinusoidal wave forms ( fictitious )according to the Fourier series. So the rippled DC now divided ( fictitious ) in to a pure DC and sinusoidal AC wave forms having the frequency that is multiples of ripple frequency. Now the DC current will not pass through the capacitor as the capacitor blocks DC. But the AC will pass through it i.e the ripple wave forms that are divided ( fictitious ) in to sinusoidal AC wave forms will pass through the capacitor. So only DC current enters in to the load, which will produce a pure DC voltage drop across the load. In this manner the capacitor smoothens the voltage.
What observation is made when using a bigger value for a capacitor in a full wave bridge rectifier?
bigger capacitor value will make the discharge taking longer time and that is willmake the curve is closer to dc line which means the higher capacitor value will help to have a closer signal to the dc and reduce the ripple voltage
Why capacitor in transistor amplifier circuit at input?
Because capacitor not allow to pass dc voltage,but capacitor allow ac voltage and signal.Purpose is to block dc voltage.That is coupling condenser.
What will happen if two terminals of capacitor are shorted?
When the terminals of a capacitor are connected together, the capacitor will discharge, returning to a zero potential state. Capacitors resist voltage change, meaning that if the capacitor is in a circuit that has zero voltage potential, the capacitor will eventually achieve zero potential. If the capacitor is in a circuit that has a 5 volt potential, the capacitor will seek and attempt to maintain that 5 volt potential (provided that the capacitor is rated at 5 volts or more). In an AC circuit, the capacitor will tend to smooth out the sin wave of the current, resisting change in both directions. In a DC power supply circuit, a capacitor will tend to reduce the voltage "ripple", and if the circuit is designed properly, will provide a smooth DC voltage. Shorting the terminals of a capacitor is effectively what often happens in many circuits; it's not a problem.
What happens to current flow in a capacitive when the DC voltage across the capacitor is approximately equal to the source voltage?
As long as you don't exceed the breakdown voltage of the capacitor ... which is marked right on it ... DC voltage on it produces NO current flow through it. Only AC 'appears' to flow through a capacitor, and even that appearance is bogus when you really get down to it.
What is the voltage obtained when a capacitor is placed in a dc circuit?
Eventually, the capacitor will charge to approximately the source voltage level. As this occurs, the current in the circuit will drop to near zero.
Application of capacitor?
A capacitor in its simplest form is merely two electrically conductive plates separated by an insulator from each other. As such the capacitor will block any DC voltage from passing through it, up to the electrical dielectric strength of the insulator. The capacitor will accept a DC charge and an electrical field will exist between the plates of the capacitor. The capacitor will retain this charge until it either leaks away via the high electrical resistance of the insulator, or is intentionally discharged. When an AC or varying voltage is applied to a capacitor, a varying electrical field is set up between the plates of the capacitor. This will thus pass through the capacitor, and can be seen on the opposite plate. Thus, a capacitor will pass an AC voltage. Now,as to the question, " application of Capacitor". One of the oldest and most useful of capacitor applications is filtering or smoothing the output of an AC to DC power supply. In this supply, an AC voltage is rectified by a diode into a varying DC voltage. A capacitor is placed across the output, and serves to supply voltage or "fill in" the output whenever the output voltage is less than the capacitor. The capacitor subsequently recharges on the next cycle and repeats the process. Thus, the output voltage of the power supply is smoothed out.
How do you charge a capacitor?
You charge a capacitor by placing DC voltage across its terminal leads. Make sure when using a polarized capacitor to place positive voltage across the positive lead (the longer lead) and negative voltage across the negative lead. Also make sure that the voltage you charge the capacitor to doesn't exceeds its voltage rating.
If vm is maximum peak voltage of rectifier outputthis rectifier output is connected to the capacitor filterwhat will be the approximate dc output voltage to the capacitor filter?
It should be the rms value of your supply.
