In the concept of measurement, either because of the limitations of measuring instruments as well as environmental conditions it is believed that any measurement will always yield an undue measure (actual). In this case it is assumed that the correct outcome is unknown. Deviation or difference (difference) between the measurement results (observations) and the actual results expressed as errata (errors). In measuring the voltage, for example, the results expressed by 1.5 <V <1.6 volts or V = (1.4 ± 0.1) volts. True value measurement of course be in the range of the results of this measurement.
Therefore a range of measurement values at once declared uncertainty of the results of measuring the sense of mistake or error is often not distinguishable by the sense of uncertainty to indicate the deviation measurement of the true value. For example, a write voltage measurement results with V = (10.5 ± 0.5) volts, which means that we show the results of measuring instruments read 10.5 volts (with an uncertainty / corrected measurement of 0.5 volts, while we are in the true value hose grades (from 10.5 to 0.5 = 10.0) volt up to (10.5 + 0.5 = 11.0) volts.
When performing a measurement of electrical quantities, none of which produced with perfect accuracy. Keep in mind that the actual accuracy and cause the occurrence of measurement errors. Error – error in the measurement can be classified into three types, namely: (1) a common mistake (gross-error), (2) a systematic error (systematic-error), and (3) random error (random-error).
Common mistakes (gross errors)
This error is mostly caused by human error. Among them is the measuring instrument readings errors, improper adjustments and the use of instruments that do not fit and valuation errors. Measurement errors can also occur due to negligence or bad habits, such as reading is not careful, a different recording of readings. In order to obtain optimal results, it would require more than one reading.
Can be done three times, and then averaged. If possible with different observers. Measurement error can also be caused by improper use of voltmeter, causing the loading effect on the circuit causing significant measurement errors. This error can not be avoided, but should be prevented and need of repair.
Measurement errors due to imposition Securities Voltmeter
Example: A voltmeter with susceptibility 1000 Ω / Volt read 100 volts on a scale of 150 volts when connected between opposite ends of a prisoner of unknown magnitude. These resistors connected in series with a miliamperemter. If the reading miliampermeter 5 mA, specify (1) detainee that read, (2) the value of the actual custody of the prisoners were measured, (3) the error due to the loading effect voltmeter.
Systematic errors (systematic errors)
This error is caused by deficiencies in the instruments themselves. Such as damage or their parts that wear and environmental influences on the equipment or user. This error is an error that can not be avoided from the instrument, because of its mechanical structure. Example: friction few moving components of the bearings can cause incorrect readings.
Pull spring irregular, shortening the spring, decreased traction due to improper handling or excessive loading instruments. This will all lead to errors. Aside from some of the things mentioned above there is still more that calibration errors that could lead instrument readings are too high or too low than it should be. The most appropriate way to determine the instrument has a fault or not by comparing with other instruments that have the same characteristics or to other instruments that accuracy is higher.
To avoid these mistakes by: (1) choose the right instrument for a particular application; (2) using correction factors after finding numerous errors; (3) calibrate the instrument against standard instruments. At the errors caused by the environment, such as: the effect of changes in temperature, humidity, air resistance outside, fields maknetik, and so forth can be avoided by making the air conditioning (AC), sealing components specific instrument with meetings, use of protective maknetik.
Random error (random-error)
Random unintentional errors (random errors) due to causes that can not be immediately known. Among other things because the changes of parameters or measurement system occurs randomly. On the planned measurement errors – errors are usually only small. But for the job – a job that requires high accuracy effect. Suppose a measured voltage with a voltmeter read every hour, although the instrument used has been calibrated and environmental conditions have been set in such a way, but the readings will occur differences during the observation period. To resolve this error by adding the amount of reading and using statistical methods to obtain accurate results.
Electrical measuring instrument before it is used to measure the note placement. This is important because the position on the moving parts that show the amount will be influenced by gravity moving parts of a measuring instrument such. Therefore, the location of the use of measuring instruments need to be considered carefully.