is used in the lab, so that any value of resistance between minimum and maximum specified can be used. It eliminates the possibility of having the meter in the circuit without a shunt. 1.16 Multi range D.C. voltmeter: We can obtain different Voltage ranges by connecting different value of multiplier resistor in series with the meter. The number of these resistors is equal to the number of ranges required. Problems: A moving coil instrument gives a full scale deflection of 10mA, when the potential difference across its terminal is 100mV. Calculate The shunt resistance for a full scale deflection corresponding to 100A The resistance for full scale reading with 1000V. Calculate the power dissipation in each case? Solution: The inductance of a moving iron instrument is given by is the deflection in radian from zero position the spring constant is Estimate the ‘θ’ deflection for a current of 5A Instrument Transformers: The d.c circuits when large currents are to be measured, it is usual to use low-range ammeters with suitable shunts. For measuring high voltages, low-range voltmeters are used with high resistances connected in series with them. But it is neither convenient nor practical to use this method with alternating current and voltage instruments. For this purpose, specially
is used in the lab, so that any value of resistance between minimum and maximum specified can be used. It eliminates the possibility of having the meter in the circuit without a shunt. 1.16 Multi range D.C. voltmeter: We can obtain different Voltage ranges by connecting different value of multiplier resistor in series with the meter. The number of these resistors is equal to the number of ranges required. Problems: A moving coil instrument gives a full scale deflection of 10mA, when the potential difference across its terminal is 100mV. Calculate The shunt resistance for a full scale deflection corresponding to 100A The resistance for full scale reading with 1000V. Calculate the power dissipation in each case? Solution: The inductance of a moving iron instrument is given by ‘θ’ is the deflection in radian from zero position the spring constant is Estimate the deflection for a current of 5A Instrument Transformers: The d.c circuits when large currents are to be measured, it is usual to use low-range ammeters with suitable shunts. For measuring high voltages, low-range voltmeters are used with high resistances connected in series with them. But it is neither convenient nor practical to use this method with alternating current and voltage instruments. For this purpose, specially
EMS-Lecture-Notes.docx