Browsing Category
Technical Articles
Class A commutation or Resonant Commutation
Class A commutation or Resonant Commutation
Figure 35 shows the Class A commutation circuit where L and C are commutation components and RL is load resistance. For low value of load resistance, RL, L and C are connected in series as…
Read More...
Read More...
Commutation Techniques
Line Commutation and Forced Commutation Circuits
Once thyristors operate in the ON state, carrying forward current, they can only be turned OFF by reducing the current flowing through them to zero for sufficient time to allow the removal…
Read More...
Read More...
Snubber Circuit
Snubber Circuit
In most power electronic circuits, protection is necessary against the effects of excessive rate of rise of forward voltage (dv/dt) across the devices, which can otherwise cause unintended breakover, leading to a…
Read More...
Read More...
String Efficiency and Derating
String Efficiency
For series or parallel connected SCRs, it should be ensured that each SCR rating is fully utilized and the system operation is satisfactory. Therefore, string efficiency is a term that is used for measuring the degree…
Read More...
Read More...
Parallel Operation of Thyristors
Parallel Operation of Thyristors
The need to connect thyristors in parallel arises when the current or over current to be handled by the apparatus or equipment exceeds the rating of a single thyristor. Thyristors can be connected…
Read More...
Read More...
Equalising Network
Equalising Network
Voltage equalisation under these conditions can, however, be achieved by connecting shunt-capacitors as shown in Figure 28. This capacitor removes inequalities in thyristor self-capacitances. Therefore, during turn-off…
Read More...
Read More...
Series Operations of Thyristors
Series Operations of Thyristors
If the required voltage rating of the assembly or equipment incorporating thyristors is more than the voltage rating of a single thyristor, then several thyristors have to be united in a series connection.…
Read More...
Read More...
Ratings of SCR
Ratings of SCR
All semiconductor devices have definite limits to their capability and exceeding these even for short times will result in failure, loss of control, or irreversible deterioration. All thyristors, therefore, have to be used…
Read More...
Read More...
Overcurrent Protection of SCRs
Overcurrent Protection of SCRs
As the thyristors have a restricted overcurrent capacity, special fast-acting fuses and circuit breakers are usually provided for overcurrent protection. As the fault current increases, the fuse opens and…
Read More...
Read More...
Overvoltage Protection of SCRs
Overvoltage Protection of SCRs
It is almost always necessary in a power semiconductor equipment to provide a means of limiting transient overvoltages which could otherwise overstress the semiconductor devices. To protect against all…
Read More...
Read More...