Basic Electrical Measurements |
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Page 106
... midscale reading 500 S. The current with Rx = 0 is 3 I = = = 6 mA 500 The shunt current = Ish 60.1 = 5.9 mA The shunt resistance 0.1 Rsh = = 250 = - 4.24 Ω 5.9 The combined resistance 1 R = = 4.17 Ω 1 1 + 250 4.24 The ranging resistor ...
... midscale reading 500 S. The current with Rx = 0 is 3 I = = = 6 mA 500 The shunt current = Ish 60.1 = 5.9 mA The shunt resistance 0.1 Rsh = = 250 = - 4.24 Ω 5.9 The combined resistance 1 R = = 4.17 Ω 1 1 + 250 4.24 The ranging resistor ...
Page 108
... reading is midscale when R , = 100 N. The meter sensitivity Im does not play a direct role in the ohm- meter sensitivity , but its effect is not negligible . Lower Im requires higher circuit resistance and R ,, which will lower the ...
... reading is midscale when R , = 100 N. The meter sensitivity Im does not play a direct role in the ohm- meter sensitivity , but its effect is not negligible . Lower Im requires higher circuit resistance and R ,, which will lower the ...
Page 109
... midscale reading . Since the combined resistance , Re , of the movement and Rsh is 50 ( the midscale reading ) and Rm = 200 N , Rsh can be calculated by rearranging the parallel resistor formula : 1 Rsh = 1 1 Rc Rm In this example 1 Rsh ...
... midscale reading . Since the combined resistance , Re , of the movement and Rsh is 50 ( the midscale reading ) and Rm = 200 N , Rsh can be calculated by rearranging the parallel resistor formula : 1 Rsh = 1 1 Rc Rm In this example 1 Rsh ...
Common terms and phrases
ac bridges accuracy and precision accurate adjustable resistor ammeter average balanced calibration capacitance components construction current going decade box deviation plot digital meter diode electrical equation Example full-scale deflection full-wave germanium given Half-wave hysteresis input impedance linear loading effect loading error loop low resistances main resistor measured values measuring instrument ment meter movement meter resistance meter sensitivity midscale reading midscale resistance multiturn null detector number of significant Ohm's law ohms output impedance parallel ohmmeter PMMC meter PMMC movement pointer position potentiometer potentiometric circuits precision problem R₁ R₂ ranging resistor ratio reactance readability readout rectifier reference accuracy resis rotating scientific notation series ohmmeter shown in Figure shows shunt significant digits source output impedance span supply voltage switch tance tion true voltage units V₁ variable resistor Vave volt voltage drop voltage measured voltmeter Vrms Weston cell wiper ΚΩ