Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Athens ProgrammeAthens Programme

Metrology of Electrical Quantities

Laboratory of Precision Electrical MeasurementsDepartment of MeasurementsFaculty of Electrical EngineeringCzech Technical University in Prague

Responsible professor:Prof. Ing. Jaroslav Bohacek, DrSc.Phone +420 22435 2220E-mail bohacek@fel.cvut.cz

http://measure.feld.cvut.cz/...

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

William Thomson, Lord Kelvin

I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it …

… but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind.

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Brian W. Petley

Far from being a dull area of science, high-precision measurements are an increasingly exciting area in which to work, for they push theory and experiment to the very limits of which they are capable…

If we recall that the rich oil deposits under the North Sea remained unknown until the advent of the very precise geophysical measurements, or that the spin of the electron was inferred from precise spectroscopic measurements, we see more clearly the class of discoveries which can come from precise measurement.

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Courseobjectives Lectures

Previousintro

Laboratorydemonstrations

Laboratoryvisit

What ismetrology?

Please, select some topic above to continue

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Laboratory demonstrations

1. Thompson-Lampard's capacitance standard

2. Frequency performance of  resistance standards

3. Calibration of capacitance boxes

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Course objectives:

to present an overview of modern and perspective methods for precision measurements of electrical quantities,

to demonstrate various techniques used in calibrations of electrical measurement instruments and standards.

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Lectures

Lecture 1

Introduction

Measurement units and measurement standards

Quantum standards of voltage and resistance

Thompson-Lampard's capacitance standard

Equivalent circuits of standard resistors, capacitors and inductors

Resistors with calculable frequency performance

Transfer standards

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Lectures

Lecture 2

Voltage and current inductive ratio devices and optimization of their metrological parameters.

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Lectures

Lecture 3

Methods for precision measurement of dc current and dc voltage

Modern potentiometers

Measurement of voltage, power and energy in audiofrequency range

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Lectures

Lecture 4

Bridges for dc and ac measurements of resistance

Transformer and current-comparator-based capacitance bridges

Metrological applications of the quantum Hall effect (QHE)

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

What is Metrology?

Metrology is the science of measurement.

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

What is Metrology?

Metrology covers three main activities:

1. The definition of internationally accepted units of measurement, e.g. the metre.

2. The realization of units of measurement by scientific methods, e.g. the realization of a metre through the use of lasers.

3. The establishment of traceability chains by determining and documenting the value and accuracy of a measurement and disseminating that knowledge, e.g. the documented relationship between the micrometer screw in a precision engineering workshop and a primary laboratory for optical length metrology.

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

1. Scientific metrology deals with the organisation and development of measurement standards and with their maintenance (highest level).

2. Industrial metrology has to ensure the adequate functioning of measurement instruments used in industry as well as in production and testing processes.

3. Legal metrology is concerned with measurements where these influence the transparency of economic transactions, health and safety.

What is Metrology?

Metrology is considered in three categories with different levels of complexity and accuracy:

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Systematic measurement with known degrees of uncertainty is one of the foundations of industrial quality control and, generally speaking, in most modern industries the costs bound up in taking measurements constitute 10 -15% of production costs.

Laboratory of Precision Electrical Measurements , CTU - FEE in Prague

Laboratory visit:

Czech Metrology Institue

Calibration of digital multimeters

Quantum Hall effect based calibrations of resistance standards

www.cmi.cz

Laboratory of Precision Electrical Measurements , CTU - FEE in PragueLaboratory of Legal Metrology, CTU Prague

See you in Prague!