2. The speed can be controlled in both the course of turn of the engine effectively.

3. The engine can run with a uniform increasing speed.

4. Speed guideline of DC engine right now framework is excellent.

Hindrances

1.High beginning expense.

2.The by and large effectiveness is low, under 80% as a result of an extra engine generator set.

4.4 Using controlled rectifiers and DC choppers

Controlled rectifier

A controlled rectifier changes over air conditioning voltage to a dc voltage. This yield voltage can be constrained by shifting the terminating edge of SCR’s.

Kinds of thyristor drives:

DC engines for various applications require speed control a forward way, turn around heading and regenerative braking. Shut circle control is constantly utilized in all thyristor drives.

The different sorts of thyristor drives utilized are:

1.Single stage half-wave controlled rectifier circuits for dc engines upto 1 kW rating.

2.Single stage half extension circuits for dc engines upto 5 kW rating.

3.Three stage half extension circuits for dc engines of 5 to 75 kw rating.

4.Three stage full extension circuits for dc engines of 75 to 400 kw rating.

5.Twelve heartbeat converters for dc engines of rating surpassing 400 kW.

Single-stage half-wave thyristor drive

This sort of drive is utilized for dc engines, which are of changeless attractive fields and evaluated for 1 kW or less.

The circuit chart is appeared in Figure.

Single-stage half-wave thyristor drive

The dc voltage over the armature can be constrained by shifting the activating or terminating point of the thyristor. With the expansion in terminating point a, the armature voltage and current are diminished and the engine runs more slow.

With the reduction in terminating point the armature voltage and current are expanded and engine runs quicker.

An elective plan for speed control of an independently energized dc engine is represented in figure in which exchanging voltage is changed over into dc voltage and provided to the field winding and SCR gives half wave correction and control to the armature winding