The following losses
take place during on condition of the SCR.
Home » Archives for April 2017
27/04/2017
26/04/2017
Heat Sink
- The function of the heat sink is to absorb heat of the semiconductor device and dissipates it to surrounding medium by thermal conductivity.
- It transfers heat from high temperature to low temperature. The heat sink plays important role for cooling of semiconductor device.
20/04/2017
Selenium Diode
- The metal oxide varistor or selenium diode is used to protect semiconductor device against transient over voltage or high dv/dt.
- The MOV is called as voltage dependent Non linear resistor.
Metal Oxide Varistor ( MOV )
Metal oxide Varistor (MOV)
- The MOV is a non linear resistor.
- There are two metal particles oxide layers are separated by insulation. When voltage across MOV increases beyond its specific value, the
14/04/2017
Snubber Circuit
- The SCR may be turned on due to transient or high dv/dt voltage across it in spite of switch S is kept open.
- The SCR may damage due to this type of surge voltage.
13/04/2017
10/04/2017
Over Current Protection of Semiconductor by Fuse
- The fault current flows through power converter due to short circuit, surge current or over load condition.
- The semi conductor device may damage due to increase of temperature due to fault current.
Current - Time Characteristic of Fuse
Current – Time Characteristics
- The fast acting fuse is used to protect semi conductor device.
- The fuse is connected in series with semi conductor device and it open when the current exceeds its rated value.
09/04/2017
08/04/2017
Effect of Transformer Winding Reactance on Performance of Three Phase Uncontrolled Rectifier
- The effect of transformer winding reactance on the performance of output voltage / current is explained here.
- The conduction of diode D1, D2 and D3 and resulting flow of current is shown in the figure A.
07/04/2017
Working of Six Phase Half Wave Uncontrolled Rectifier
- The connection diagram for six phase half wave uncontrolled rectifier is shown in the figure A.
- The primary winding of the transformer is connected in delta whereas the secondary winding consists of center taped star winding.
05/04/2017
Working of Three Phase Uncontrolled Full Wave Rectifier
- The connection diagram for three phase full wave uncontrolled rectifier using Delta – star transformer is shown in the figure A.
- There are two diodes used for each phase and load is connected between common anode terminal and common cathode terminal of diodes.
Working of Three Phase Half Wave Uncontrolled Rectifier
- Figure A shows a three phase half wave uncontrolled rectifier circuit using delta – star transformer.
- The anode of the diode D1, D2 and D3 are connected to the secondary winding of the transformer with R phase, Y phase and B phase respectively.
Class F Commutation ( Line commutation or AC commutation )
- The class F commutation is also called as line or natural commutation because the SCR is turned off automatically during negative cycle of alternating supply.
- There are no commutating components used in this method therefore it is not called as forced commutation method.
Class E Commutation ( External Pulse or Type E commutation )
- The class E commutation is also called as external pulse commutation because the SCR is turned off by external source.
- The SCR is turned off by applying reverse voltage across it.
- Figure A shows the external pulse commutation by using transistor.
04/04/2017
Class D Commutation ( Impulse or Auxiliary Commutation )
- The class D commutation is also called as impulse commutation.
- The SCR T1 is main SCR whereas SCR T2 is auxiliary SCR.
- The auxiliary SCR T2 is used to turn off main SCR T1 therefore this method is also called as auxiliary commutation.
02/04/2017
Class C Commutation ( Voltage or Complementary or Type C Commutation )
- The class C commutation is also called as voltage commutation because the SCR is turned off by applying reverse voltage across it.
- The SCR T1 is main SCR which is connected in series with load.
- The commutating capacitor C is connected between
anode terminal of SCR T1 and SCR T2.