Errors and Compensation

Q. A voltage of 200 V produces a deflection of 90° in a PMMC spring controlled instrument. If the same instrument is provided with gravity control, then the deflection would be

1. 90°
2. 45°
3. 64.2°
4. cannot be known from the data given

Q. A PMMC instrument is spring controlled. The control stiffness decreases by 0.02 percent per degree Celsius rise in temperature and magnetic field strength decreases by 0.01 percent per degree Celsius rise in temperature. If the rise in temperature is ${10}^{o}C,$ the instrument's reading

1. decreases by 0.1 percent.
2. increases by 0.2 percent.
3. increases by 0.1 percent
4. decreases by 0.2 percent

Q. Two $100\mu A$ full sale PMMC meters are employed to construct a 10 V and a 100 V full scale voltmeter.These meters will have figure of merits (sensitivities)as

1. $10k\Omega /Vand10k\Omega /V$
2. $100k\Omega /Vand10k\Omega /V$
3. $100k\Omega /Vand100k\Omega /V$
4. $10k\Omega /Vand1k\Omega /V$

Q. A DC voltage with ripple is given by $v\left(t\right)=[100+10sin(\omega t\left)\right)]volts.$ Measurements of this voltage $v\left(t\right)$, made by moving-coil and moving-iron voltmeters, show readings of $V_1$ and $V_2$ respectively. The value of $V_2-V_1$, in volts, is

1. 0.312