Energy Calibration

Report
ISRAEL ELECTRIC CORP.
METER TESTING LABORATORIES DEPARTMENT
STANDARDS LABORATORY
Development
of the Electricity
Metering Laboratories
in Israel
Shalomygin Maxim
Gueta Itshak
Standards Laboratory;
Mahban Khosrow
Electronic Meters Development;
National Metering Department
Israel Electric Corporation
17, Halehi Street, Bnei Brak 51200, Israel.
[email protected]
Preparing of the tests and calibrations
procedures.
Calculation of the measuring and calibration
uncertainties.
Training of the laboratory personnel.
Electrical energy is one of the main
factors for the strategic development of
our country.
Proper generation and consumption of
electrical energy should be based on
metrological aspects.
Technological progress is impossible
without metrological support.
The Standard Metering Laboratory of
the Israel Electric Corp. maintains
and develops a system of national
standards for the electrical power
and energy metering.
This system depends on a rigid
hierarchic quality control system.
The main aim of the
metering laboratory is
maintaining traceability.
Electricity meters and EPE
meters.
Transducers and transformers for
support of the EPE meters.
Adjustable power sources.
Energy dosage, delivered to device under test.
Indirect methods to test electricity meters.
Direct calibration with standard devices.
Precision in measuring predetermines
technology progress. It makes
possible to develop new technologies,
produce new systems and devices.
It is extremely important to reduce
uncertainty of measurements.
The CMC (Calibration and Measuring Capability)
of our laboratory is 150 ppm for the calibration
of the electrical power and energy meters.
Optionally we can achieve about 70 ppm.
Automation of the measuring
procedures.
Unification and standardization of the
different measuring system types.
Improve metrological compatibility of
the measuring systems and units
under test.
The reference electricity meter
includes sources/references of
the DC voltage and frequency
sources.
They should be calibrated
periodically
(at least once every 3 months).
Storage of data of the calibrations
gives the opportunity to provide
statistical analysis.
Statistical analysis is an important and
useful activity of our laboratory. We
provide tests of hypotheses, method
of maximum probability and
regression analysis.
Measurement and analysis of dynamic
processes. Characteristics of some
physical processes depend on
different dispositions and nonsynchronous measuring. In these
cases some processes could be
regarded as random processes.
Competition and collaboration
between laboratories.
Expanding the capability of the
metering laboratory.
Correct calibration of the electricity
meters requires compliance with the
validated methods, and taking into
account the influence factors.
Human factor
Power quality of the power
sources
Electromagnetic compatibility (EMC)
of measuring equipment, cables and
external equipment.
Normal ambient conditions
Transducers, transformers and
assessment equipment.
Since results of calibrations are
highly sensitive to the influence
factors, the metering laboratory must
expand its capability to take into
account the influence factors.
*There are several schemes for electricity meter
connections to the three phase network.
*Reference meters have a limited range of
measuring capability.
*Reliable calibrations period depends on the drift
of deviation of the unit under test from
traceable values.
Comparison between precision EPE meters;
Test of the internal counter and generator
of the specific pulses frequency;
Test of the internal meter and source of DC
voltage.
Tests of the drift
include:
C = R + D – B;
Where:
R – measured result of the comparison;
D – result of the calibration of the meter
which counts pulses;
B – result of the calibration of the meter
which generates pulses;
*C smaller than the calculated value of CMC
in specified range;
*Absolute difference of present and
previous results of the comparisons is less
than half of the annual drift limit value;
*Standard square root deviation of the
results of pair-wise comparisons between a
few precision meters should be smaller
than admissible value. Admissible value of
the standard square root deviation could
be calculated according to the NeimanPierson criterion.
These are a few practical
recommendations, and I hope it
will prove interesting for the
different kinds of the
calibration laboratories.
Thank you for your attention.

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