ALFF ENGINEERING Switzerland ALFF ENGINEERING SWITZERLAND ALFF ENGINEERING Switzerland Conductivity Meter for Liquids LCM-8716 A QUICK INTRODUCTION HOW TO PERFORM EASY AND ACCURATE MEASUREMENTS OF CONDUCTIVITY AND TAN  ON INSULATING LIQUIDS

ALFF ENGINEERING Switzerland The equipment THE ELECTRONIC MEASURING DEVICE THE CELL TWO CABLES A THERMOMETER

ALFF ENGINEERING Switzerland Determination of Permittivity  r, Conductivity  and Dissipation factor, tan  =  /2  f  o  r According to IEC standard* ) *) Insulating liquids – Determination of the dielectric factor by measurement of the conductance and capacitance – Test method Measurement based on so called „low amplitude, low frequency“ method, applying an alternate square wave voltage Amplitude of applied voltage: 30 V Frequency of applied voltage: 0.5 Hz

ALFF ENGINEERING Switzerland Applied voltage u(t) Generated current i(t) Time I C =C V/T F I R =V/R=GV +V -V Capacitance: C=I C T F /V=  o  r C o Conductance: G=I R /V=(  /  o ) C o I R : resistive current I C : capacitive current TFTF Principle of operation applying an alternate square wave vol tage

ALFF ENGINEERING Switzerland Determination of Dissipation Factor, tan  According to IEC Standard Measured quantities: Resistive Current: I R and Capacitive Current: I C Derived quantities: Conductance: G=I R /V and Capacitance: C=I C  T F /V Derived and displayed quantities: Conductivity:  =  o G/C o and Relative Permittivity:  r =C/  o C o where, C o : vacuum capacitance of measuring cell  o : permittivity of vacuum equal to  As/Vm Derived quantity: Dissipation Factor, tan  =G/2  f  C=  /2  f  o  r where, f: main frequency i.e. 50 Hz or 60 Hz

ALFF ENGINEERING Switzerland Conformity and compatibility of standards  The LCM-8716 is developed according to IEC Standard* ) and works with so called “low amplitude, low frequency, alternate square wave method”.  The classic measurement of dissipation factor with an AC voltage is based on IEC Standard** ).  The IEC Standard is a complement to the IEC one.  The measured dissipation factors according both standards are identical. *) Insulating liquids – Determination of the dielectric factor by measurement of the conductance and capacitance – Test method **) Insulating liquids – measurement of relative permittivity, dielectric dissipation factor (tan  ) and d.c. resistivity

ALFF ENGINEERING Switzerland Characterisation of electrical insulating liquids with conductivity, permittivity and dissipation factor  IEC Standard: Fluids for electrotechnical applications – Unused mineral insulating oils for transformers and switchgear  IEC Standard: Mineral insulating oils in eletrical equipment – Supervision and maintenance guidance  IEC Standard: Specifications for unused synthetic organic esters for electrical purposes These quantities are very sensitive to the presence of soluble polar contaminants and aging products. For the recommended limits see the following standards:

ALFF ENGINEERING Switzerland Advantages of the „low amplitude, low frequency“ method in comparison to the classic method with AC excitation voltage:  Accurate measurement of conductivity (respectively dissipation) factor  Simple design of test cell, low excitation voltage of only 30 V  No influence onto the properties of the liquid proprieties during the measurement (from charge injection into the liquid tested from measuring electrodes).  Comparatively cheap price of cell and measurement instrumentation.  Portable, low weight, no mains required, easy to clean

ALFF ENGINEERING Switzerland Test cells  Simple design without guarding electrodes  Easy to clean  Low ratio “electrode surface”/ “liquid volume” minimising the contamination effects from the surface in contact with the liquid.  Comparatively cheap cell price Standard cell (160 ml) disassembledFlow cell

ALFF ENGINEERING Switzerland Heater The heater with PID controller permits accurate measurements in function of temperature from ambient temperature to 90°C (optionally 120°C) Heater only Heater with cell in receptacle

ALFF ENGINEERING Switzerland Evaluation software “LCM-8716 calculator” Generation of reports Input quantities equal to measured quantities Computed quantities e.g. tan  in function of temperature (extrapolation) Characterisation of temperature dependency from measurement of liquid tested at two different temperatures