Tettex MIDAS 2881, Operating Instructions Manual

Page: 59 / 164

Software 49
Text “Value Cn internal”
This information shows the value of the internal standard
capacitor. The value is set in the factory, or by
recalibration, therefore this value should not be modified
by the operator.
Extended GST Accuracy
The stray capacitance between high voltage cable and
earth is located in parallel to the test object capacitance
and therefore influences the measurements while using
the ground input chanel (GST A+B, GST gA, GST gB,
GST gA+B.).
The MIDAS offers you the possibility to measure this stray
capacitance and compensate it to increase the accuracy
while using this measuring modes. For normal test
operation this procedure is normally not necessary.
During this test the device will apply high voltage, please follow the safety rooles as while performing
the test
By pressing ”Evaluate Parameters”, the evaluation procedure will be started You are guided with the
connection diagram:
You have to bring the HV cable very close to the test object where it shall be connected but don’t
connect it.
Pay attention that you don’t touch the cable during energizing.
After the cable will be energized with the set voltage the capacitance and the dissipation factor of the
stray capacitance will be measured.
Button “Evaluate Parameters”
By pressing this button a procedure to determinate the
parameters of the stray capacitance will start.
See picture above.
Input “Test Voltage Stray Capacitance”
At this voltage the stray capacitance will be measured.
Text “Stray Capacitance ”
After successful measuring of the stray capacitance this
field will be filled by the capacity of the stray capacitance.