What is the effect of positive feedback on stability of the system?
Positive feedback is not used generally in the control system because it increases the error signal and drives the system to instability. But positive feedbacks are used in minor loop control systems to amplify certain internal signals and parameters.
Positive feedback is not used generally in the control system because it increases the error signal and drives the system to instability. But positive feedbacks are used in minor loop control systems to amplify certain internal signals and parameters.
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What is Latching current?
Gate signal is to be applied to the thyristor to trigger the thyristor ON in safe mode. When the thyristor starts conducting the forward current above the minimum value, called Latching current, the gate signal which is applied to trigger the device in no longer require to keep the scr in ON position.
Gate signal is to be applied to the thyristor to trigger the thyristor ON in safe mode. When the thyristor starts conducting the forward current above the minimum value, called Latching current, the gate signal which is applied to trigger the device in no longer require to keep the scr in ON position.
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What is Holding current ?
When scr is conducting current in forward conduction state, scr will return to forward blocking state when the anode current or forward current falls below a low level called Holding current
Note: Latching current and Holding current are not same. Latching current is associated with the turn on process of the scr whereas holding current is associated with the turn off process. In general holding current will be slightly lesser than the latching current.
When scr is conducting current in forward conduction state, scr will return to forward blocking state when the anode current or forward current falls below a low level called Holding current
Note: Latching current and Holding current are not same. Latching current is associated with the turn on process of the scr whereas holding current is associated with the turn off process. In general holding current will be slightly lesser than the latching current.
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Why thyristor is considered as Charge controlled device?
During the triggering process of the thyristor from forward blocking state to forward conduction state through the gate signal, by applying the gate signal (voltage between gate and cathode) increases the minority carrier density in the p-layer and thereby facilitate the reverse break over of the junction J2 and thyristor starts conducting. Higher the magnitude of the gate current pulse, lesser is the time required to inject the charge and turning on the scr. By controlling the amount of charge we can control the turning on time of the scr.
During the triggering process of the thyristor from forward blocking state to forward conduction state through the gate signal, by applying the gate signal (voltage between gate and cathode) increases the minority carrier density in the p-layer and thereby facilitate the reverse break over of the junction J2 and thyristor starts conducting. Higher the magnitude of the gate current pulse, lesser is the time required to inject the charge and turning on the scr. By controlling the amount of charge we can control the turning on time of the scr.
What are the different losses that occur in thyristor while operating?
Different losses that occur are
a)Forward conduction losses during conduction of the thyristor
b)Loss due to leakage current during forward and reverse blocking.
c)Power loss at gate or Gate triggering loss.
d)Switching losses at turn-on and turn-off.
Different losses that occur are
a)Forward conduction losses during conduction of the thyristor
b)Loss due to leakage current during forward and reverse blocking.
c)Power loss at gate or Gate triggering loss.
d)Switching losses at turn-on and turn-off.
What is meant by knee point voltage?
Knee point voltage is calculated for electrical Current transformers and is very important factor to choose a CT. It is the voltage at which a CT gets saturated.(CT-current transformer).
Knee point voltage is calculated for electrical Current transformers and is very important factor to choose a CT. It is the voltage at which a CT gets saturated.(CT-current transformer).
What is reverse power relay?
Reverse Power flow relay are used in generating stations's protection. A generating stations is supposed to fed power to the grid and in case generating units are off,there is no generation in the plant then plant may take power from grid. To stop the flow of power from grid to generator we use reverse power relay.
Reverse Power flow relay are used in generating stations's protection. A generating stations is supposed to fed power to the grid and in case generating units are off,there is no generation in the plant then plant may take power from grid. To stop the flow of power from grid to generator we use reverse power relay.
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What will happen if DC supply is given on the primary of a transformer?
Mainly transformer has high inductance and low resistance.In case of DC supply there is no inductance ,only resistance will act in the electrical circuit. So high electrical current will flow through primary side of the transformer.So for this reason coil and insulation will burn out.
Mainly transformer has high inductance and low resistance.In case of DC supply there is no inductance ,only resistance will act in the electrical circuit. So high electrical current will flow through primary side of the transformer.So for this reason coil and insulation will burn out.
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What is the difference between isolators and electrical circuit breakers? What is bus-bar?
Isolators are mainly for switching purpose under normal conditions but they cannot operate in fault conditions .Actually they used for isolating the CBs for maintenance. Whereas CB gets activated under fault conditions according to the fault detected.Bus bar is nothing but a junction where the power is getting distributed for independent loads.
Isolators are mainly for switching purpose under normal conditions but they cannot operate in fault conditions .Actually they used for isolating the CBs for maintenance. Whereas CB gets activated under fault conditions according to the fault detected.Bus bar is nothing but a junction where the power is getting distributed for independent loads.
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What are the advantage of free wheeling diode in a Full Wave rectifier?
It reduces the harmonics and it also reduces sparking and arching across the mechanical switch so that it reduces the voltage spike seen in a inductive load.
It reduces the harmonics and it also reduces sparking and arching across the mechanical switch so that it reduces the voltage spike seen in a inductive load.
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The different methods of starting an induction motor:
a)DOL:direct online starter
b)Star delta starter
c)Auto transformer starter
d)Resistance starter
e)Series reactor starter
a)DOL:direct online starter
b)Star delta starter
c)Auto transformer starter
d)Resistance starter
e)Series reactor starter
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What is the power factor of an alternator at no load?
At no load Synchronous Impedance of the alternator is responsible for creating angle difference. So it should be zero lagging like inductor.
At no load Synchronous Impedance of the alternator is responsible for creating angle difference. So it should be zero lagging like inductor.
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What is the function of anti-pumping in circuit breaker?
When breaker is close at one time by close push button,the anti pumping contactor prevent re close the breaker by close push button after if it already close.
When breaker is close at one time by close push button,the anti pumping contactor prevent re close the breaker by close push button after if it already close.
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What is stepper motor.what is its uses?
Stepper motor is the electrical machine which act upon input pulse applied to it. it is one type of synchronous motor which runs in steps in either direction instead of running in complete cycle. so, in automation parts it is used.
Stepper motor is the electrical machine which act upon input pulse applied to it. it is one type of synchronous motor which runs in steps in either direction instead of running in complete cycle. so, in automation parts it is used.
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There are a Transformer and an induction machine. Those two have the same supply. For which device the load current will be maximum? And why?
The motor has max load current compare to that of transformer because the motor consumes real power.. and the transformer is only producing the working flux and its not consuming.. hence the load current in the transformer is less because of core loss.
The motor has max load current compare to that of transformer because the motor consumes real power.. and the transformer is only producing the working flux and its not consuming.. hence the load current in the transformer is less because of core loss.
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What’s a Volt? A unit of electric force, measuring the potential strength of current.
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Water doesn’t actually conduct electricity. Impurities in water is what makes it conduct electricity.
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Electricity is a type of energy that builds up in one place, or flows from one place to another. When electricity gathers in one place it is known as static electricity. Electricity that moves from one place to another is called electric current.
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