Question

What are the methods of energy conservation in electrical drives

Answer 1

Various methods of energy conservation in electrical drives are as follows:-

1. Use of energy efficient motors---this means machines with proper lamination amd insulation, good mechanical design of bearing, clutchers, gears and coupling, should be used.

2. Variable Speed Drives---Several drives are driven at constant speeds by induction or synchronous motors although operation at variable speed could lead to saving of substantial amount of energy. These methods were discovered because of non availability of efficient methods of speed control of induction and synchronous motors. This kind of practice saves20-40% of energy.

3. Improvement in Power Factor---

There are two ways for improving pf:

[I].Overexcited synchronous motors

When connected direct on line a synch. motor runs at constant speed, it draws leading reactive power when overexcited so it is one of the method of power factor improvement.

[II]. Static Capacitor

This is used when speed control is not required. Induction motors are widely used in these applications. Power factor of such drives can be corrected (improved ) by permanently connecting a fixed capacitor across the motor terminals.

4.Using a motor of right rating---Over sizing of motor has several disadvantages such as higher motor cost, higher power modulator cost, higher installation cost, lower power factor & efficiency, & higher losses.

5. Improvement of quality of supply---Due to inadequate reactive power compensation, there are variations in motor terminal voltage .In order to avoid low voltage, substation transformers should be set for higher voltages. Under light load condition, over voltage conditions are produced. Another major issue is the unbalance of supply voltage. A small unbalance in voltage produces large unbalance in current and a large increase in losses. Sharp fluctuation of voltage due to loads like arc furnace and welding machines.

6. Regular and preventive maintenance of motors, trasnformers amd coupled equipments--Friction losses in motors and elect. losses in transformers and motors are reduced by proper amd regular maintenance of motors and transformers. Oiling of bearings, and setting of brakes, brushes,Proper condition of cooling fans and transformer oils, etc.