what causes saturation in welding machine
In class B amplifier no DC biasing required, thus lack of of DC current in inpunt and load, saturation of core avoided
Inrush current is a result of core saturation. The magnetic flux in the core of a transformer is 90 degrees out of phase with the voltage. Ideally the transformer switching device will be closed at a peak voltage, and the transformer core will have no residual flux from the last close. If this occurs, the flux in the core in the first cycle will be no larger than it normally would be. If the switching device closes at a zero voltage, or there is some residual flux, the transformer's core will be driven into partial saturation within the first cycle, unless it has been oversized to prevent saturation. Decreasing the applied voltage at energization will keep this from occuring. One method is to use pre-insertion resistors which cause a voltage drop to the transformer that is significant enough to prevent saturation within the first few cycles, and then they are removed. Another method is to de-engerize the transformer core, and close at voltage peaks only (controlled closing).
in welding machine, the transformer used is basically a current transforrmer. so by changing the tap of secondary side of transformer, we can increase or decrease the current in the transformer.
why does have to short-circuit secondary wire of current transformer ?
DC current cannot be used in a transformer only AC will work. A transformer needs the continual build and collapse of the magnetic field to keep the iron core from reaching saturation. Only alternating current will transfer power through a transformer.
what causes saturation in welding machine
David John Corns has written: 'Current transformer saturation and the effect on protective devices'
Core saturation occurs in electrical transformers when the magnetic flux in the core reaches its maximum limit, resulting in a decrease in efficiency and potential overheating. It can be caused by excessive current or voltage in the transformer, leading to distortion in the output waveform and potential damage to the transformer.
In class B amplifier no DC biasing required, thus lack of of DC current in inpunt and load, saturation of core avoided
It will get core saturation
Inrush current is a result of core saturation. The magnetic flux in the core of a transformer is 90 degrees out of phase with the voltage. Ideally the transformer switching device will be closed at a peak voltage, and the transformer core will have no residual flux from the last close. If this occurs, the flux in the core in the first cycle will be no larger than it normally would be. If the switching device closes at a zero voltage, or there is some residual flux, the transformer's core will be driven into partial saturation within the first cycle, unless it has been oversized to prevent saturation. Decreasing the applied voltage at energization will keep this from occuring. One method is to use pre-insertion resistors which cause a voltage drop to the transformer that is significant enough to prevent saturation within the first few cycles, and then they are removed. Another method is to de-engerize the transformer core, and close at voltage peaks only (controlled closing).
Electrical Engineering
This is a class of current transformers, and is a fairly low class. This has to do with what kind of burden can be placed on the secondary. A general rule is a C200 current transformer can supply ~200 volts at full ratio to its' secondary. If the burden (the CT resistance + cable resistance + relay or instrument resistance) times the maximum expected current is higher than 200 volts, the CT is likely to saturate. During multiple fault events, a CT may keep some magnetizing current causing CT saturation to be higher on a reclose event. Typically CT's are sized and their ratios are chosen to minimize saturation when feasible.
in welding machine, the transformer used is basically a current transforrmer. so by changing the tap of secondary side of transformer, we can increase or decrease the current in the transformer.
why does have to short-circuit secondary wire of current transformer ?
Saturation region is one in which the output current is independent of the input and remains almost constant. Hence, MOSFETs in saturation are modeled as current sources( whose current is independent of voltage across it)