Conductivity meter
Portable instrument, light and self-contained Conforms the new IEC61620 Standard Wide conductivity volumen range: 0.01 pS/m to 20’000 pS/m
The measuring instrument type TAND220A conforms to the new IEC 61620 Standard. This instrument is based on the so-called “low amplitude, low frequency, alternate square wave method” and permits accurate measurement of volume conductivity and relative permittivity. The measurement of volume conductivity in the range of 0.01 pS/m to 20’000 pS/m allows the use of this instrument for quality assessment of high resistive liquids even at ambient temperature. The TAND220A works with low voltage and low current levels and represents no danger at all for its operators.
FEATURES
MEASURINGMETHOD
- Accurate and fast measurement of the volume conductivity from
- 10-14to 10-8S/m and the relative permittivity r up to 5.
- Determinationofthedissipationfactoratpowerfrequencies down to values of 10-6
- Determination of the discharge time constant of electric volume charges as produced by triboelectric effects.
- Optionalanalogueoutputsforcontinuousrecordingofthe measured values
- Portable instrument, light and self-contained
- Compact test cell, easy to use, easy to clean
APPLICATIONS
- Testanddocumentationoftheconductivity(orresistivity)of highlyinsulatingliquidsusedinelectricalequipmentas transformers,bushings,cables,capacitorsandotherhighvoltage apparatus
- Controlofthedielectricqualityofliquidinsulationduringthe manufacturing of electrical equipment
- Control of the liquid insulation quality for maintenance decisions
- Monitoringoftheliquidinsulationqualityforfailurealert purposes
- Detection of the ionic purity of high resistance liquids: tests during the synthesis of liquids, purity checking on chemicals and mineral or organic oils, ageing and degradation studies
The liquid in the test cell is excited with a low amplitude (30 V) low frequency (0.5Hz) alternate square wave voltage without any DC component (see figure).
BymeasuringthecurrentthroughtheliquidthecapacitanceCandtheconductanceGcanbe determined and the values of relative permittivity r and volume conductivity are given according to the following equations:
The derived dissipation factor tanfor a Applied voltage u(t)givenfrequencyfcanbedetermined +Vaccording to the following equation: Time TF -VFor determination of conductivity or Generated current i(t)IR: resistive tan, the alternate square wave method IR=V/R=GVcurrentis, by far, more sensitive than the classic IC=CV/TF bridgemethod.Itpermitsthe IC: capacitive currentdeterminationofconductivityvalues downto0.01pS/mrespectivelytan Timevaluesdownto1E-6(at50Hz).This Conductance:highsensitivityallowsaccurate Capacitance:measurementsofconductivityandtan; atlowtemperaturesandconsequently thecharacterisationofliquidsatroom Principle of operation using the alternate square temperaturecanbecarriedoutwith wave methodconfidence.
Principle of operation using the alternate square wave method
TEST CELL
Theapplicationofasquarewaveexcitationvoltage withlowamplitudeofonly±30Vpermitsthe developmentofatest cellwithsimpledesign,easyto use and to clean.
The compact test cell is composed of only two parts, a containerandanactivepart.Twocoaxialelectrodes (stainlesssteel)areattachedonacap(alsostainless steel).ThiscapalsosupportstwoBNCconnectors coupled to the two electrodes. The electrodes possess a clean, polished surface. The vessel and the active part canbecleanedaccordingtoproceduresdescribedin the appendix A. It is not possible and not necessary to disassemble the active part for cleaning purposes. The required amount of liquid for a test is about 210 ml. To reach this amount,fi ll in the liquid to be tested up to 23 mm from the top edge of the vessel.
Thetemperatureofthetestedliquidcanbe determined by introducing the electronic thermometer in the cell through the cover orifice (included)
SPECIFICATIONS
| Electro | onic measuring instrument -14 -8 |
|---|---|
| Conductivity measuring range | 10 -14 ... 2×10 -8 S/m on four ranges |
| Uncertainty of conductivity measurements | ±1 digit ±1% of indicated value -14 |
| Resolution of conductivity measurements | 10 -14 S/m for conductivities up to 19.99 pS/m 10 -13 S/m for conductivities up to 199.9 pS/m 10 -12 S/m for conductivities up to 1.999 nS/m 10 -11 S/m for conductivities up to 19.99 nS/m |
| Resolution of permittivity measurements | 0.001 for relative permittivities up to 1.999 0.01 for relative permittivities from 2.00 to 5.00 |
| Uncertainty of permittivity measurements | ±1 digit ±0.2% of indicated value |
| Calibration of the test cell | Simple on-site adjustment for test cells from 50 to 70 pF |
| Frequency of the measurement voltage | 0.5 Hz |
| Amplitude of the measurement voltage | ±30 V square wave with no dc part |
| Analogue outputs | 2 V for 0 to 100% |
| Analogue outputs voltage span | 0 ... 2 V for 0 to 100% of chosen range, short circuit proof |
| Weight | 2.6 kg |
| Size(width × depth × height in mm) | 260 × 283 × 115 |
| Power supply in the fi eld | six batteries type AA alcaline for several hours of operation |
| Power supply in the lab | universal mains adapter 100 ... 240 Vac 50/60 Hz delivering 6VDC |
| Temperature (use) | 0 ... 35°C |
| Temperature (stock) | -10 ... 50°C |
| Pressure | 70 ... 106 kPa |
| Humidity | 5 ... 80% non condensing |
| Acceleration | <2g |
| Test cell | |
|---|---|
| Required amount of liquid | 210 ml |
| Vacuum capacitance | 60 pF |
| Capacitance drift with temperature | < 50 ppm/°C |
| Electrode gap | 1.5 mm |
| Material | stainless steel |
| Electrical connection | two standard 50Ω BNC plug |
| Temperature measurement | glass thermometer or electronic thermometer |
| Weight | 1.2 kg |
| Size (height × diameter in mm) | 125 × 82 |
Optional accesories:
The instrument heats and maintains the temperature of the samples at a temperature of 90ºC ± 0.1 ° C to carry out the measurement in accordance with the IEC standard.
Z2 -Flow cell
The vessel for continuous measurement of tan delta is an oil circuit like that of an oil treatment plant. The probe for continuous measurement will be installed at the outlet of an oil circuit after the pump. A certain amount of oil will pass through the probe for the continuous measurement of tan delta.