State differences between AC and DC generator diagramatically.
Answers
Answer:
Sl. No.
Differentiating Property
>AC Generator
>DC Generator
1]Definition
>AC generator is a mechanical device which converts mechanical energy into AC electrical power.
>DC generator is a mechanical device which converts mechanical energy into DC electrical power.
2]Direction of Current
>In an AC generator, the electrical current reverses direction periodically.
>In a DC generator, the electrical current flows only in one direction.
3Basic Design
>In an AC generator, the coil through which the current flows is fixed while the magnet moves. The construction is simple and costs are less.
>In a DC generator, the coil through which the current flows rotates in a fixed field. The overall design is very simple but construction is complex due commutators and slip rings.
4]Commutators
>AC generator does not have commutators.
>DC generators have commutators to make the current flow in one direction only.
5]Rings
>AC generators have slip-rings.
>DC generators have split-ring commutators.
6]Efficiency of Brushes
>Since slip-rings have a smooth and uninterrupted surface, they do not wear quickly and are highly efficient.
>Both brushes and commutators of a DC generator wear out quickly and thus are less efficient.
7]Short Circuit Possibility
>As the brushes have high efficiency, a short circuit is very unlikely.
>Since the brushes and commutators wear out quickly, sparking and short circuit possibility is high.
8]Armature
>In case of AC generators, the armature is always the rotor.
>In case of DC generators, the armature may be either rotor or stator.
9]Rotating Parts
>The rotating part in an AC Generator is low current high resistivity rotor.
>The rotating part in a DC generator is generally heavy.
10]Current Induction
>In AC generator, the output current can be either induced in the stator or in the rotor.
>In DC generator, the output current can only be induced in the rotor.
11]Output Voltage
>AC generators produce a high voltage which varies in amplitude and time. The output frequency varies (mostly 50Hz to 60Hz).
>DC generators produce a low voltage when compared to AC generator which is constant in amplitude and time i.e. output frequency is zero.
12]Maintenance
>AC generators require very less maintenance and are highly reliable.
>DC generators require frequent maintenance and are less reliable.
13]Types
>AC generators can of varying types like 3 Phase generators, Single phase generators, synchronous generator, induction generator, etc.
>DC generators are mainly two types which are Separately excited DC generator and Self-excited DC generator. According to field and armature connection, they can be further classified as DC series, shunt or compound generators respectively.
14]Cost
>The initial cost of AC generator is high.
>The initial cost of DC generator is less when compared to AC generators.
15]Distribution and Transmission
>The output from AC generators is easy to distribute using a transformer.
>The output from DC generators is difficult to distribute as transformers cannot be used.
16]Efficiency
>AC generators are very efficient as the energy losses are less.
>DC generators are less efficient due to sparking and other losses like copper, eddy current, mechanical and hysteresis losses.