1 Three-phase Energy Meter Test System (MTS)
First steps in the production of fully electronic automatic electricity meter calibration
systems were made 10 years ago by KAIPU. The system described and offered here
comprises components based on most modern technologies. It therefore combines long
term experience in this field with the application of state of the art technology.The recently developed new software is based on KAIPU ’s historical experience in providing various testing solution to numbers of manufacturers, Utility companies, Metrological institutes etc.

 

1.1 General features
The offered universal meter testing equipment is designed for the simultaneous testing,
adjustment and certification of meters.
The following electricity meters of the accuracy classes 0.2, 0.5, 1 and 2 can be tested:
*2 wire-, 3 wire- and 4 wire meters for active and reactive energy (true and cross-connected),

The test system incorporates a completely electronic test current- and test voltage
generation. The working standard is a wide range substandard meter directly connected to the test circuit.

A PC system controls the test system and supervises the test procedure. The actual
values of test voltage and -current and the errors of the meters under test are displayed on the monitor. The errors of the meters are indicated additionally on error displays at each measuring position.

The user software supports the following operation modes:

*Creation of type table and test tables (sequences). Editing of already prepared test
sequences and type tables also possible

 

*Manual testing of meter, in this case test voltage, current, PF, Frequency, Phase
sequence, measurement mode can be selected and set for the testing. Operator will be
allowed to input meter constant to check the % error of meter under test. Error results can be directly printout

 

*Automatic certification, using type- and test tables

*Results of Automatic testing, Storage, printout, formatting etc.
The meters to be tested will be suspended on a stationary meter rack
The basic version of the test system consists of the following components:

*1 power supply unit , designed as 19“-cabinet with the modules for test

voltage and test current generation as well as the reference standard,

*1 test tables with meter test rack for the simultaneous testing equipped with:
Scanning devices for rotor mark detection of inductive type meters and LED detection ofelectronic meters,
* IR-data heads                       *1 PC system with user software
*Central error calculator          * Individual error displays

 

The test system will be connected directly to the unsterilized mains:
220 V (Phase to Neutral) + 10 % -- 15 %, 50 Hz ±2 %

 

1.2 Power supply unit
Test current and -voltage are synthetically generated in a Fully Digital Electronic Power
Source by the means of a 6-channel frequency generator (extendable to 8 channels) and resonant Switch Mode Amplifiers.
These Amplifiers have the following Characteristics:
*High Efficiency
*DDC control by signal processors,
*PF compensation of the mains connection according To EN 60555 / IEC 555
*High stability at inductive-, capacitive-and non-linear loads
*very good quality of the output signals, low THD
*Electronically Protected against overload and short circuit
*Designed as 19“-unit, digital controlled by fiber-optics connection.
*Diagnostic features in amplifier to detect the problem
The Frequency Generator allows in combination with the wide range amplifiers the
superposition of harmonics.
The Closed Loop Control conception of the frequency generator guarantees a high
stability and precision of test voltage and test current, in absolute value as well as in phase
angle. The deviation between the selected test value and the actual value is Monitored
Continuously. Deviations beyond the previously selected close tolerance will be indicated
as error message. This technology of inherent calibration guarantees the highly precise
generation of the output settings under all load conditions.
A malfunction will be indicated by acoustic- and optic signal.

 

1.2.1 Frequency Waveform Generator
The waveform generator is the central unit of the synthetic waveform generation. It
generates the set points for the digital control of the power amplifier units, carries out the closed-loop control of the test settings and controls changeover operations during the test procedure. The output settings per phase are generated with a resolution of 3600 samples per period and 16 bit in amplitude.

 

The Technical Data of the Frequency Generator are:
Test circuit frequency computer controlled adjustable to :
*mains synchronized operation f =50 or 60 Hz,
*quartz controlled operation f = 45.00 to 65 Hz,
adjustable in steps to 0.01 Hz.

Test voltage circuit Selectable in the range of
*40 to 380 V (phase-neutral)
*70 to 658 V (phase-phase)
*Individual phase can be controlled

Test current circuit Selectable in the range of
*1 mA to 120 A
*Individual phase can be controlled

Phase position adjustment to any power factor
cos φ / sin φ = 0.000 to 1.000 in all computer controlled.

Symmetrical/Unsymmetrical
Test voltage and current can be freely selectable as symmetrical / unsymmetrical,
balance/unbalance system

 

Superposition of harmonics
*In the range 2nd ... 21th harmonic to each test voltage- and test current phase individually. Two different waveform/channel

*Magnitude of each harmonic is adjustable over 0 ...40 % and phase angle w.r.t to the fundamental wave

 

1.2.2 Test voltage amplifier

 

The three - phase test voltage amplifier is designed for generation of desired test
parameter, based on the command received from frequency generator

 

Voltage range: 40 to 380 V (phase-neutral)
                         70 to 658 V (phase-phase)
Accuracy of the test setting amplitude: 0.05 %
Accuracy of the test setting phase
adjustment: 0.01°
Stability of the output settings: < 0.05
Distortion factor: < 0.5 %
Superposition of harmonics 2 to. 21. Harmonics
Output power in the test voltage circuit: max. 3 x 2000 VA.

Protection:

Mains is protected by Fuse and output
circuit is Protected against short
circuit/overload

Communication:

send/receive signal through fiber optic cables.

Failure Diagnosis feature:

Amplifier has built in self-diagnosis features, which can be activated to detect the fault inside the amplifier

 

1.2.3 Test current amplifier
Each of the 3 single-phase test current amplifiers is designed for:
Current range: 1mA -120A
Accuracy of the test setting amplitude: 0.05 %
Accuracy of the test setting phase adjustment: 0.01°
Stability of the output settings: < 0.05
Distortion factor: < 0.5 %
Superposition of harmonics 2. ... 21. Harmonics
Output power in the test current circuit: max. 1500 VA per phase

Protection:

Mains is protected by Fuse and output circuit is Protected against open circuit/overload

Communication send/receive signal through fiber optic cables.

Failure Diagnosis feature Amplifier has built in self-diagnosis features, which can be activated to detect the fault inside the amplifier