What is a shunt resistor used for?
A shunt is a low-ohm resistor that can be used to measure current. Shunts are always employed when the measured current exceeds the range of the measuring device. The shunt is then connected in parallel to the measuring device.
What does a shunt do in a generator?
A shunt generator is a type of direct current electric generator in which field winding and armature winding are connected in parallel, and in which the armature supplies both the load current and the field current.
Why is it called a shunt resistor?
In electronics, a shunt is a device that creates a low-resistance path for electric current, to allow it to pass around another point in the circuit. The origin of the term is in the verb ‘to shunt’ meaning to turn away or follow a different path.
How is the terminal voltage of a shunt generator controlled?
The terminal voltage of a shunt generator can be controlled by means of a rheostat inserted in series with the field windings as shown in A of figure 9-16. As the resistance is increased, the field current is reduced; consequently, the generated voltage is reduced also.
How does a shunt generator start?
When the DC shunt machine is used as a generator, the starting field flux is built from residual magnetism. Sometimes the field winding is replaced by a permanent magnet, then the generator is called DC permanent magnet generator; this is what is used for small wind turbine generators.
Why do we use shunt?
What is critical resistance of DC shunt generator?
Critical field resistance is a term that is associated with a shunt DC generator. In a DC shunt generator, the voltage induced across the armature, Va, is directly proportional to the flux acting across it, The flux in a DC generator is directly proportional to the field current, If.
How do you control voltage of generator?
The output of a generator is normally controlled by controlling the current in the field of the generator, the speed being constant for a set frequency. Various excitation systems are possible and all usually include some system of sensing and controlling the generator output voltage.
What is critical resistance of a shunt generator?
The critical field resistance is defined as the maximum field circuit resistance (for a given speed) with which the shunt generator would just excite. The shunt generator will build up voltage only if field circuit resistance is less than critical field resistance.
Where are shunt generators used?
Applications of shunt generator:
- Used for general lighting.
- Used to charge the battery because they can be made to give constant output voltage.
- Used for giving the excitation to the alternators.
- In process of Electroplating.
- Used for small power supply (such as a portable generator)
What is the name of shunt resistance material?
Copper, Brass, Manganin are the most widely used materials for shunt resistors.
What is critical speed in shunt generator?
Critical Speed (NC): The critical speed of the DC generator is the minimum speed below which it fails to excite. It is the speed at which the given shunt field resistance represents the critical speed.
Is shunt resistance and field resistance same?
Critical Field Resistance of DC Shunt Generator The critical field resistance (RC) of a DC shunt generator is defined as the maximum field circuit resistance with which the shunt generator would just excite. The voltage build-up in a shunt generator depends upon field circuit resistance.