Electronics & Software – Tips & Guide


Does AC current also rise and fall in sinusoidal movement, like voltage?

AC current also rise and fall in sinusoidal

Does the ac current also rise and fall in the sinusoidal movement, such as voltage. The ac current rises and falls like no voltage but the inductive and / or capacitive reactance in the circuit affects the phase and waveform.

A sinusoidal voltage applied to a pure resistive load will have a sinusoidal current in phase with a voltage.The sinusoidal voltage applied to a pure inductive load will have a phase whose phase is lagging behind. frequency and inductance values can also change the shape of the current waveform.

The sinusoidal voltage applied to the pure capacitive load  will have a current whose phase leads the voltage. frequency and capacitance value can also change the shape of the current waveform.

AC current also rise and fall in sinusoidal

For a sinusoidal ac voltage, as you can get from 115 outlet, depending on the type of circuit (load, source type, etc.). I use 43 chance to measure the current and ac voltage applied to lighting fixtures. if the light source is a conventional lamp, current and voltage will increase and decrease at the same time. if measuring the fixture with a large transformer, the current will be delayed with respect to the current due to the inductive reactance of the transformer. if the fixture has a switching power supply without power factor (pf) correction, the current will precede the voltage because the large capacitors of this power supply are on the ac side of their circuit. however, with the pf corrector installed, the current will be very close to the voltage.

In other circuits, the current may not exist all the time. imagine that you want to reduce heat dissipation from large soldering iron (300 w or more). in this case, you connect the corresponding characteristic diode in series with the internal resistor . in this case, the current will only flow for every other half cycle.  you can connect the switch in parallel to the diode to pass it.

If you replace the diode with a scr (silicon controlled rectifier) with the right timing circuit, the current will flow less than half the conduction cycle, depending on the delay set by the control potentiometer. this will reduce further dissipation. note that even when the potentiometer is set to zero delay, there is always a small delay (no conduction) caused by scr.

If replacing the diode with triac (triode for alternating current), instead, the current will flow for all half cycles, although the conduction time will depend, again, on the time delay set by the control potentiometer. this should provide a wider range of controls (from nearly 100% to almost 0%).

  • Normally yes.
  • Normally because there are non-linear loads, such as power converters, led lamps, dimmers, etc., which deform the current.
  • So you may find rectangular, triangular, and wird shaped currents.
  • As long as the distortions are small, it is not necessary to correct this. in part, they will even be filtered by the impedance of the grid.
  • If the distortions exceed certain values, they must be corrected using appropriate filters.
  • The voltage will normally be deformed too much at the flow rate of these deformed currents through the line impedances, but to a lesser degree.
  • Leave strong uncorrected distortions, cause radio disturbances, higher line losses and many problems.
  • Electronic equipment, computers, etc. can be strongly disturbed by the existence of distortions