Draw a circuit diagram showing a single-phase wattmeter measuring the power in a single-phase 6.6 kV 500Acircuit by means of current and voltage transformer

1.The resistance material used for meter shunts is chosen for its very low value of

 

temperature coefficient of resistance. Why is this so? 2.State briefly with the aid of circuit diagrams

(a) how to extend the range of a 0–110 V AC voltmeter to read (i) 220 V and

(ii) 22 kV;

(b) how to extend the range of a 0–5 A AC ammeter to read 500 V;

(c) how to extend the range of a 0.5 A DC ammeter to read 500 A.

3.Draw a circuit diagram showing a single-phase wattmeter measuring the power in a single-phase 6.6 kV 500Acircuit by means of current and voltage transformers.

4.Calculate the sensitivity in ohms/volt of voltmeters giving full-scale deflection with currents of (a) 10 mA, (b) 0.5 mA and (c) 50 μA.

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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….