Modern insulation analyzer Sonel MIC-15k1
Insulation resistance testing is commonly associated with periodic inspections of electrical installations. This is a relatively simple operation and it takes more time to prepare the circuit for measurement than the measurement itself. The rating is pass-fail. If the insulation resistance is higher than 1 MΩ, it can still be operated (for circuits with nominal voltage up to 500 V HD-60364:2008). Devices for this type of measurement are relatively simple, and the choice among the various models is very large.
Pic. 1. Insulation analyzer Sonel MIC-15k1
Measurements of insulation resistance of cables, motors or transformers look quite different. Assessment of insulation condition for such objects is more complicated. It requires, in addition to measuring the resistance itself, verification of various factors resulting from phenomena occurring during measurements. For example, there are objects with large capacitance, which determines the required parameters for the HV converter in the meter. New insulation resistance analyzer from SONEL S.A., MIC-15-k1 is a device that sets a new trend in this type of research.
The meter is designed to measure the insulation resistance of power objects, including single and multi-core cables, transformers, motors and generators, capacitors, breakers and other power station equipment. It is especially recommended for measurements in areas with very high electromagnetic disturbances, e.g. at power stations with 1200 kV AC or 500 kV DC. Thanks to the measuring voltage of 15 kV (in accordance with ANSI / NETA ATS-2009 TABLE 100.1), the meter can be used for objects with a nominal voltage above 34.5 kV. The HV converter deserves special attention. With a power of nearly 150 W (15 kV, current up to 10 mA, range up to 40 TΩ), it makes this meter unrivaled in this class of instruments on the world market. Such parameters allow to burn the insulation of the tested cable, making it easier to locate the place of insulation damage, e.g. short circuit. This can be checked visually (if the cables are visible along the entire length), using reflectometric methods, a seismic-acoustic wave receiver or a voltage drop measurement method – A frame (LKZ-1500 when the cables are buried). The device is equipped with a number of diagnostic functions of insulation systems based on standard Insulation Resistance (IR), Dielectric Absorption Ratio (DAR), Polarization Index (PI), Step Voltage (SV), Ramp Test (RT), Dielectric Discharge (DD) measurements, extended by the partial discharge indicator (PD) for each of these measurements.
The function of continuous voltage rise over time (RT) makes it possible to determine the presence of partial discharges in the object and to conduct a segmental location of their place of occurrence. Assessment of insulation condition is possible by setting the measuring voltage increase in steps (SV) or continuously (RT). The SV method makes a dielectric in good condition provide the same results, regardless of the applied voltage. The RT method, where voltage increases linearly, enables to determine the insulation properties of the material. The meter smoothly increases the measuring voltage without exposing the object to the so-called electrical stress. The time and value of the voltage at which the electrical breakdown occurs is recorded. Built-in digital filters with averaging time of 10, 30, 60, 100 and 200 seconds guarantee stable measurement results in areas with strong electromagnetic interference.
The meter itself is equipped with a large segment LCD display and is supported with free Sonel MIC Mobile application. It provides result observation and plotting graphs of different parameters in real time, during the measurement. This allows to assess the condition of the object already during the test, because the shape of the graph carries information about the state of insulation, even when the measurement has not yet been completed. The possibility of remote start and stop of measurement is particularly useful. Thanks to this, the tests can be carried out remotely, e.g. from another room or a car, when climatic conditions are inconvenient for the operator. Using the phone's GPS, the exact place of the measurement can be determined. Thanks to the mobile application and the Sonel Reader software, the user can collect historical data and compare it with recent results transferred from the meter's extensive memory. This solution allows to prepare a measurement report, track the progress of insulation deterioration and plan renovation work. An invaluable convenience for the user is the automatic measurement recording function, in case the operator forgot to enter the result into the analyzer memory. The meter automatically saves all measurements (in temporary memory) that can be identified by the date and time of their execution, thanks to the meter's internal Real Time Clock (RTC).
Pic. 2. Mobile aplication screen
To sum up, the MIC-15k1 is an extremely modern, ergonomic device with intuitive operation. It will satisfy even the most demanding users, in the most difficult conditions, at high interference, where other meters will be useless.
The pioneering solution of combining insulation resistance measurement with partial discharge indicator makes this analyzer one of the most powerful diagnostic tools for electrical insulation in the world.
