Explain the principle on which the Wheatstone bridge works. Show how it could be used to measure the resistance of a busbar joint by comparison with a standard 0.1 _ resistor.

1.Explain the principle on which the Wheatstone bridge works. Show how it could

 

be used to measure the resistance of a busbar joint by comparison with a standard 0.1 resistor.

2. Draw a schematic circuit diagram of a Wheatstone bridge arranged for resistance measurement. Prove the relationship between the resistances at ‘balance’. Set out resistances, labelling each with its value, representing a bridge at balance when the measured resistance is 1.752 _. The variable-resistor dials give units, tens, hundreds and thousands, 0–10 of each; the ratio arms can each be set at 10, 100, 1000 or 10 000 _.

find the cost of your paper

Sketch the load characteristics, terminal voltage/load current, of the following types of DC generator

1. (a) Sketch the load characteristics, terminal voltage/load current, of the following types of DC generator: (i) series-connected, (ii) shunt-connected and (iii) compound-connected.   (b) State one purpose for which….

what happens if the resistance in series with the shunt field of a DC motor is increased in value

1. Sparking at the trailing edges of the brushes in a DC machine is usually prevented by fitting   (a) copper gauze brushes (b) a compensating winding (c) a compound….

Calculate the synchronous speed of a 10-pole three-phase machine connected to a 50 Hz supply.

1. The generator characteristic shown in Figure 9.28 is for a   (a) shunt machine (b) series machine (c) differentially compounded machine (d) cumulatively compounded machine 2.The speed of a….