# A load test on a DC series motor and its characteristic and efficiency

## Apparatus required

• DC Series Motor
• Voltmeter
• Ammeter
• Tachometer

### DC Series Motor

It is a type of motor that is generally used to produce mechanical rotating force. In every rotating machine, there is a field coil that produces a magnetic field and the second one is an armature coil that gets the all magnetic field and produces a torque the result is motor rotates he called it a series motor because its armature coil and field coil both are connected in series combination. if we put a current on it without circuit completion it will not work the reason is the same because both coils are connected in a series combination.

### Voltmeter

Voltmeter is a device that measures the voltage in a circuit but there is a condition that should be followed in the case of a voltmeter that is voltmeter should be connected to any kind of circuit parallel if we put the voltmeter in a circuit parallelly so we can get applying voltage on that circuit but the applying voltage should be in the range of voltmeter if we exceed the voltmeter range so it will burn out or we can use a register during connection of voltmeter in an original circuit so we can extend the range voltmeter and we can measure any voltage of circuit this process is also called range extension of the voltmeter.

### Ammeter

Ammeter is also a device that measures the current flowing in the circuit so the connection of a meter in a circuit is series. It is put on any circuit wire to get the current of that wire and its condition is similar to the voltmeter. Ammeter should be connected in series combination with the circuit and the current up should be approximately in the range of the ammeter otherwise it will be burned. If you want to measure the more current capacity of the Ammetre so we can use the range extension of the ammeter nothing in it only be put a suitable resistance across the ammeter so it gradually increases the range of the Ammeter and rather than fix the value of register we can put available register so by the user of the variable register we can extend the range of Ammeter.

### Tachometer

Tachometer instruments measure the rotation of the motor nowadays people use digital tachometer. Process of using a tachometer so we put a piece of paper on the motor rotating part. Tachometer has a laser lens and laser light also which is put on the piece of paper of the rotating part of the motor after crossing the laser lens it counts 1 rotation but putting a laser-only piece of paper is very difficult so the tachometer gives a very large fluctuating value and it gives a large number of variable value which create some error in our final value.

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### Working principle

The working principle of this overall experiment is if we put a spring load on the DC series motor or weight with the help of a belt on the rotating pulley on the motor so it increases the current in the ammeter.
Starting torque of the DC motor is too much high, without some mechanical load on it we cannot start this DC motor.
Different load radii of the rotor and with the help of these things we can measure efficiency and characteristics graph.

### Procedure to find characteristics and efficiency

1. Connections are made as per the circuit diagram
2. There is the use I started to start the DPST motor and the circuit is closed so the DPST switch is removing resistance gradually after checking the load condition.
4. For various loads ammeter voltmeter and tachometer readings are noted with balance spring weight.
5. After bringing the load to the initial position DPST switch is opened.

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### Physical meaning

The physical meaning of this experiment is the weight of the pulley of a motor is increased so the motor required tomorrow current to rotate and if the weight of the pulley of the motor is less so motor required less current to rotate and I will recommend having a proof 200 stand the rotation and wait of you can compare with both it is similar like inversely proportional each other and another one of them will increase so another required in less quantity.

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