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The initial factors are the working voltage and power level required. These set the size of the machine.
There are three types of dc machine depending on how the internal magnetic field is produced. A permanent magnet machine gives a constant excitation field and is preferred for smaller motors since no field winding is needed and the machine is therefore simpler.
A shunt-wound machine has the field winding in parallel with the armature (the rotating part) and is the commonest type of dc machine. This is used for high-power motors or generators (they are the same thing) where the speed of operation is fairly constant.
A series-wound machine has the field winding in series with the armature. This type is used in traction, to drive trams and trolley-buses. The torque produced by a dc machine is proportional to the field current and also to the armature current, so a series motor produces torque proportional to the square of the current. When starting, the motor draws a high current limited only by the resistance in circuit, so the torque is very high and suitable for starting the vehicle. A switched starting-resistor keeps the current within limits.
A standard shunt-wound motor acts as a motor when a mechanical load is applied, but if the motor is driven faster than it rotates naturally without a load, then power flows back into the supply and it becomes a generator.
A shunt-wound motor tends to behave as a capacitor because the starting current is high and it then reduces exponentially as the rotor gathers speed. If the supply is disconnected, the terminal voltage reduces exponentially as the speed runs down. In a capacitor the energy is stored in the electric field while in the dc machine it is in the kinetic energy of the rotor.
What else can I help you with?
Is DC safer than AC in terms of electrical systems?
DC is generally considered safer than AC in terms of electrical systems because DC does not cause the same level of electric shock and is less likely to start fires.
Which type of electrical current, AC or DC, is considered more dangerous in terms of potential harm to humans and property?
AC (alternating current) is generally considered more dangerous than DC (direct current) in terms of potential harm to humans and property. This is because AC can cause muscle contractions and fibrillation at lower levels of exposure compared to DC.
Why is DC considered better than AC in certain applications?
DC is considered better than AC in certain applications because it is easier to control and store, making it more suitable for devices that require a steady and constant flow of electricity, such as batteries and electronic devices. Additionally, DC is often more efficient for transmitting power over long distances, as it experiences less energy loss compared to AC.
Which type of electrical current, AC or DC, is more dangerous?
Both AC and DC electrical currents can be dangerous, but AC is generally considered to be more dangerous than DC. This is because AC can cause muscles to contract involuntarily, making it harder for a person to let go of a live wire. DC, on the other hand, typically causes a single muscle contraction, making it easier for a person to release the source of the shock.
What are the differences in voltage drop between AC and DC systems?
In AC systems, voltage drop is affected by factors like resistance and reactance, leading to a more complex calculation. In DC systems, voltage drop is mainly influenced by resistance, resulting in a more straightforward calculation.
What motor is NOT suitable for use as a DC machine?
What motor is NOT suitable for use as a DC machine?
What is the important of brush in DC machine?
The slip rings are the most important brush in DC machine.
What is swinburne's test of DC shunt motor?
swinburne's test on dc shunt machine is to predetermine the efficiency of the dc machine , but it is not accurate it is just like estimation of efficiency of dc shunt machine when it is run as a motor and a generator............................
What is an dc meachine?
it is a machine which operates on the dc power source.
How many types of DC machine?
05 types of dc machines
Derive emf equation of a DC machine?
equation of ac machine
How do you make DC generator?
A DC generator is a DC machine that is driven by an external rotating force. It is constructed the same as a DC motor.
Whether a pmbldc motor is a dc or ac motor?
PMBLDC machine is actually an ac machine and due to power electronics components it's output is dc ,so therefor it is called 'dc'
What component of a welding machine changes AC current to DC current?
Yes, it is normal for a welding machine to convert AC voltage to a DC voltage.
How AC is converted into DC in welding machine?
rectifyer
Are we able to do swinburne's test on all dc machine?
no
Can you Wire a 12 volt DC Adaptor into a machine that takes 4 D bateries without burn the machine up?
Can you wire a 12 volt DC adaptor into a machine that uses 4 D batteries without ruining it?
