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As detailed in an instrument catalog, a power quality
Chapter , Problem 7.43(choose chapter or problem)
As detailed in an instrument catalog, a power quality analyzer has the following specifications: Voltage (V): Current (1): Power factor (PF): 600 V (rms) range, accuracy 1 % of reading 1-1000 A, 1 % of reading 2% of reading Using the formula P = V x I x PFv'3, (a) Calculate the uncertainty in power measurement as a percentage of reading due to the measurement device for measured values of 460 V, 36 amp, and a power factor of 0.81. (b) In logging data with a high sampling rate, the calculated standard deviations of the readings are 3.00 V, 2.00 A, and 0.03 for the power factor, while the mean values are 460 V, 35.00 A, and 0.81 for the power factor. Determine the random and systematic uncertainty of the measurements. (c) What is the total uncertainty in the power measurement at a 95% confidence level?
Questions & Answers
QUESTION:
As detailed in an instrument catalog, a power quality analyzer has the following specifications: Voltage (V): Current (1): Power factor (PF): 600 V (rms) range, accuracy 1 % of reading 1-1000 A, 1 % of reading 2% of reading Using the formula P = V x I x PFv'3, (a) Calculate the uncertainty in power measurement as a percentage of reading due to the measurement device for measured values of 460 V, 36 amp, and a power factor of 0.81. (b) In logging data with a high sampling rate, the calculated standard deviations of the readings are 3.00 V, 2.00 A, and 0.03 for the power factor, while the mean values are 460 V, 35.00 A, and 0.81 for the power factor. Determine the random and systematic uncertainty of the measurements. (c) What is the total uncertainty in the power measurement at a 95% confidence level?
ANSWER:Step 1 of 4
Random uncertainty:
We can estimate the random uncertainty using the t-distribution:
Here
The standard deviation can be determined using the same sample. That is used to determine the mean of another sample with M tests.