16-02-2015, 04:18 AM
TRIAC BASED 4 STEP TOUCH DIMMER CIRCUIT AND DESCRIPTION
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download presentation on 12 phase capacitor
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TRIAC BASED 4 STEP TOUCH DIMMER CIRCUIT AND DESCRIPTION
29-03-2017, 12:28 PM
When the capacitors or inductors are involved in an AC circuit, the current and voltage do not reach the peak at the same time. The fraction of a period difference between the peaks expressed in degrees is said to be the phase difference. The phase difference is <= 90 degrees. It is customary to use the angle at which the voltage conducts the current. This leads to a positive phase for the inductive circuits since the current delays the voltage in an inductive circuit. The phase is negative for a capacitive circuit since the current conducts the voltage. The useful mnemonic ELI the ICE man helps to remember the sign of the phase. The phase relationship is often represented graphically in a phasor diagram.
AC induction motors typically use two or more coils to generate a rotating magnetic field, which results in a torque in the rotor. When a single coil is used, it will generate a pulsating magnetic field, which is sufficient to sustain the rotation, but not sufficient to start the engine from a neutral point. Motors with a single coil must be started using an external force, and can rotate in any direction. The direction of rotation depends on the external force. If the motor starts clockwise, it will continue to rotate and increase the speed clockwise until it reaches a maximum speed defined by the frequency of the power supply. Similarly, it will continue to rotate counterclockwise if the initial rotation was counterclockwise. These engines are impractical due to their inability to reliably start the rotation by themselves.
Sometimes it is useful to treat the phase as if defining a vector in a plane. The usual reference for phase zero is taken as the positive x-axis and is associated with the resistance since the voltage and current associated with the resistance are in phase. The length of the phasor is proportional to the magnitude of the amount represented, and its angle represents its phase relative to that of the current through the resistor. The phasor diagram for the RLC series circuit shows the main features.
AC induction motors typically use two or more coils to generate a rotating magnetic field, which results in a torque in the rotor. When a single coil is used, it will generate a pulsating magnetic field, which is sufficient to sustain the rotation, but not sufficient to start the engine from a neutral point. Motors with a single coil must be started using an external force, and can rotate in any direction. The direction of rotation depends on the external force. If the motor starts clockwise, it will continue to rotate and increase the speed clockwise until it reaches a maximum speed defined by the frequency of the power supply. Similarly, it will continue to rotate counterclockwise if the initial rotation was counterclockwise. These engines are impractical due to their inability to reliably start the rotation by themselves.
Sometimes it is useful to treat the phase as if defining a vector in a plane. The usual reference for phase zero is taken as the positive x-axis and is associated with the resistance since the voltage and current associated with the resistance are in phase. The length of the phasor is proportional to the magnitude of the amount represented, and its angle represents its phase relative to that of the current through the resistor. The phasor diagram for the RLC series circuit shows the main features.
![[Image: phas2.gif]](http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/phas2.gif)
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