Before connecting the system to the grid, it is recommended to perform, together with the AC test, a partial discharge investigation in order to check presence of possible defects.
The output of the commissioning test is an accurate Technical Report, released by Service dept., containing diagnosis based on traffic light logic, conclusions and suggested actions.
Commissioning tests are the final check on the cable, in order to pinpoint eventual problems caused during the installation process.
These tests consist in the application of Hipot Test for 1 hour thanks to an external source (RTS - resonant testing system). The level of the overvoltage is specified by the specific international regulation.
Techimp personnel will provide an accurate measurement in order to verify absence of dangerous Partial discharge phenomena discriminating between possible noises or disturbances.
These tests are performed usually for 24 h simulating a typical working condition voltage stress (without load).
Techimp personnel will provide an accurate manual measurement and more data can be saved leaving the instruments on monitoring mode for all the duration of the test.
In the monitoring period the system will automatically acquire data, providing a data set for the whole 24 hours.
Commissioning tests are the final check on the cable, in order to pinpoint eventual problems caused during the installation process. In such conditions very low frequency power supply are the most fitting solution. In fact, comparing with the HV field, resonant test sets can be even more expensive than the cable system.
VLF generators are easy to carry on and can be energized with normal LV power supply. Due to the mainly capacitive load a voltage generator working at 0.1 Hz can easily energize long cables with a relatively low power.
The equipment under test is disconnected from the load and the noise is low enough to enable a time domain reflectometry analysis. Together with the Partial Discharge test it is possible to perform some macroscopic diagnostic techniques such as: polarization index and tangent delta of the cable under test.
The combination of the diagnostic results of the 3 testing techniques covers very well the possible insulation ageing problems those can occur in the lifetime of the asset.