Megger Calibrator CAL1 Manual De Usuario página 14

Performing calibration
Recalibration
Once the calibrator has been connected, switched on and set as required, the
PD measuring system can be calibrated. Proceed as follows:
Step Action
1
Remove the earthing device from the tested circuit.
2
Carry out the calibration using the PD measuring system.
For detailed instructions on how the PD measuring system is
operated and calibration is performed, please read the instruction
manual for the system.
Immediately after the calibrator is switched on and the settings have
been entered, it takes a few seconds (30 at most) for it to adjust to the
output amplitude. During that time no measurements should be taken.
3 Verify successful calibration in the course of a test measurement without high
voltage (noise measurement). The charge levels determined during that
measurement should match the previously calibrated charge.
4
Earth the tested circuit.
5
Before starting the actual measurements, remove the calibrator from the
tested circuit.
6 Remove the earthing device from the tested circuit again.
If a different circuit is connected to the PD measuring circuit, calibration has to be
repeated because even small subsequent changes to the test set-up can affect the
magnitude and shape of the pulses measured.
An exception to that rule are homogeneous three-phase cable systems or other
equipment of similar design with virtually identical capacitance (±10%). In such cases,
the calibration data established for one phase can also be applied for the other phases.
CAUTION
Risk of irreparable damage due to electrical flash-over
The calibrator is not capable of withstanding high voltages.
Switching on the high test voltage when the calibrator is
connected may irreparably damage it.
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