Question

a) Draw the connection diagram to identify the unknown terminals of D.C. compound
machine and verify by testing
b) Write the required tools, instruments, machine and naterials with specification and
procedure to perform the above task.
c) Test and identify the unknown terminals of compound machine and verify by testing.​

Answer 1

Answer:

draw tha connection diagram to identify the unknown terminals of d.c. compound machine and verify by testing

Answer 2

(a) Connection diagram to identify the unknown terminals of a DC compound machine:

To identify the unknown terminals of a DC compound machine, we need to perform a connection test.

The following connection diagram shows how to connect the machine for testing:

      +-----+  +-----+  +-----+

      |     |  |     |  |     |

 A1---|     |--|Shunt|--|     |--A2

      |     |  |     |  |     |

 F1---|Comp.|  |Fld.1|  |Comp.|---F2

      |     |  |     |  |     |

 S1---|     |--|Fld.2|--|     |--S2

      |     |  |     |  |     |

      +-----+  +-----+  +-----+

The shunt field is connected in parallel with the armature, and the two series fields are connected in series with the armature.

• To verify the connections, we can perform a polarity test and a running test. In the polarity test, we check the direction of rotation of the machine by applying a small DC voltage to the armature terminals. In the running test, we apply a full load to the machine and check its performance.

(b) Tools and materials required:

• Multimeter
• Wires for connections
• Crocodile clips
• Terminal identification labels

Procedure:

Identify the series field terminals by tracing the wire connections to the field winding. Label these terminals as "F1" and "F2".

Connect the multimeter to measure resistance and set it to the lowest range.

• Connect another wire to the other unknown terminal of the machine, and the other end to the negative (black) probe of the multimeter.
• Record the resistance reading on the multimeter.
• Reverse the connections of the two wires to the machine and record the resistance reading on the multimeter.
• If the two resistance readings are the same, the two unknown terminals are a pair of shunt field terminals. Label these terminals as "A1" and "A2".
• If the two resistance readings are different, the two unknown terminals are a pair of armature terminals. Label these terminals as "T1" and "T2".
• To verify the connections, connect the machine to a DC power supply and a voltmeter.
• Connect the armature terminals "T1" and "T2" to the power supply.
• Slowly increase the voltage of the power supply and observe the voltmeter reading. If the reading increases as the voltage increases, the connections are correct. If the reading decreases, the connections are incorrect and need to be reversed.

(c) To test and identify the unknown terminals of a compound machine and verify by testing, follow the steps below:

• Disconnect the machine from the power supply.

• Identify the series field terminals by tracing the wire connections to the field winding. Label these terminals as "F1" and "F2".

• Connect the multimeter to measure resistance and set it to the lowest range.

• Connect another wire to the other unknown terminal of the machine, and the other end to the negative (black) probe of the multimeter.

• Record the resistance reading on the multimeter.

• Reverse the connections of the two wires to the machine and record the resistance reading on the multimeter.

• If the two resistance readings are the same, the two unknown terminals are a pair of shunt field terminals. Label these terminals as "A1" and "A2".

• If the two resistance readings are different, the two unknown terminals are a pair of armature terminals. Label these terminals as "T1" and "T2".

• To verify the connections, connect the machine to a DC power supply and a voltmeter.

• Connect the armature terminals "T1" and "T2" to the power supply.

• Slowly increase the voltage of the power supply and observe the voltmeter reading. If the reading increases as the voltage increases, the connections are correct. If the reading decreases, the connections are incorrect and need to be reversed.

• Once the correct connections are identified and verified, label the unknown terminals with the appropriate labels (A1, A2, T1, or T2) for future reference.

#SPJ3