**SPEED CONTROL OF DC SHUNT MOTOR**

**AIM:**

To obtain speed control of DC shunt motor by

- Varying armature voltage with field current constant.
- Varying field current with armature voltage constant

**APPARATUS REQUIRED:**

S.No. | Apparatus | Range | Type | Quantity |

1 | Ammeter | (0-20) A | MC | 1 |

2 | Voltmeter | (0-300) V | MC | 1 |

3 | Rheostats | 1250W, 0.8A 50W, 3.5A | Wire Wound | Each 1 |

4 | Tachometer | (0-3000) rpm | Digital | 1 |

5 | Connecting Wires | 2.5sq.mm. | Copper | Few |

**PRECAUTIONS:**

- Field Rheostat should be kept in the minimum resistance position at the time of starting and stopping the motor.
- Armature Rheostat should be kept in the maximum resistance position at the time of starting and stopping the motor.

**PROCEDURE:**

- Connections are made as per the circuit diagram.
- After checking the maximum position of armature rheostat and minimum position of field rheostat, DPST switch is closed

**(i)**

**Armature Control:**

- Field current is fixed to various values and for each fixed value, by varying the armature rheostat, speed is noted for various voltages across the armature.

**(ii)**

**Field Control:**

1. Armature voltage is fixed to various values and for each fixed value, by adjusting

the field rheostat, speed is noted for various field currents.

the field rheostat, speed is noted for various field currents.

2. Bringing field rheostat to minimum position and armature rheostat to maximum

position DPST switch is opened.

position DPST switch is opened.

**TABULAR COLUMN:**

**(i) Armature Voltage Control:**

S.No. | I_{f1} = | I_{f2} = | I_{f3} = | |||

Armature VoltageV_{a} ( Volts) | SpeedN (rpm) | Armature VoltageV_{a} ( Volts) | SpeedN (rpm) | Armature VoltageV_{a} ( Volts) | SpeedN (rpm) | |

| | | | | | |

**(ii) Field Control:**

S.No. | V_{a1} = | V_{a2} = | V_{a3} = | |||

Field CurrentI_{f} (A) | SpeedN (rpm) | Field CurrentI_{f} (A) | SpeedN (rpm) | Field CurrentI_{f} (A) | SpeedN (rpm) | |

| | | | | | |

**MODEL GRAPHS:**

**RESULT:**

Thus the speed control of DC Shunt Motor is obtained using Armature and Field control methods.

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