Engineering Services Exam- Electrical Engineering Set 5

An electrodynamometer instrument can be used as
1. Wattmeter and VAR meter.
2. Power factor meter and Frequency meter.
3. Transfer instrument. Which of the above statements are correct?

The moving iron instruments when measuring voltages or currents.

True RMS-reading voltmeter
1. Measures the RMS value of voltage accurately.
2. Eliminates the error due to waveform.
3. Uses the thermocouple for heating. Which of the above statements are correct?

Instrument transformers are

The power in a 3-phase circuit is measured with the help of 2-wattmeters; the readings of one of the wattmeters is positive and that of the other is negative. The magnitude of readings is different. It can be concluded that the power factor of the circuit will be

In a Q-meter, distributed capacitance of a coil is measured by changing the capacitance of the tuning capacitor. The value of tuning capacitor are C1 and C2 for resonant frequencies f1 and 2f1 respectively. The value of distributed capacitance will be

In a digital voltmeter, during start of conversion, zero indication is displayed and is called auto zeroing. This is achieved by

A CRT has an anode voltage of 2000 V and parallel deflecting plates 2 cm long and 5 mm apart. The screen is 30 cm from the centre of the plates. If the input voltage is applied to the deflecting plates through amplifiers having an overall gain of 100, the input voltage required to deflect the beam through 3 cm will be

An aquadag is used in a CRO to collect

A resistance wire strain gauge with a gauge factor of 2 is bonded to a steel structural member subjected to a stress of 100 MN/m2. The modulus of elasticity of steel is 200 GN/m2. The percentage change in the value of the gauge resistance due to the applied stress will be