The correct answer is D. all of the above.
A rectifier instrument is a type of electrical measuring instrument that uses a rectifier to convert alternating current (AC) into direct current (DC). This DC is then used to power the instrument’s internal components. Rectifier instruments are often used to measure AC voltages and currents.
However, rectifier instruments are not free from errors. One type of error that can occur is temperature error. This error occurs because the resistance of the rectifier changes with temperature. As the temperature increases, the resistance of the rectifier decreases. This causes the DC output of the rectifier to decrease.
Another type of error that can occur is wave shape error. This error occurs because the rectifier does not convert all of the AC input into DC output. Some of the AC input is lost as heat. This causes the DC output of the rectifier to be less than the AC input.
Finally, frequency error can also occur. This error occurs because the rectifier does not convert all frequencies of AC input into DC output. Some frequencies are lost as heat. This causes the DC output of the rectifier to be different for different frequencies of AC input.
In conclusion, rectifier instruments are not free from errors. Temperature error, wave shape error, and frequency error can all occur.