The HV Diagnostics TD60 Tan Delta testing enables the cable test engineer to detect insulation defects before the cable fails in service. The TD60 is a versatile tan delta measuring system that is directly connected the HVA series of VLF test systems. The tan delta of the test object can now be quickly measured and the results stored thus providing a “signature” of the device being tested. This enables the cable engineer to now make tan delta routine test. The TD60 is a battery powered system that is directly connected to the HVA60 series of VLF test systems. The standard “C” size alkaline battery cells last for some 10hours thus providing the capacity for many tests. The TD60 is supplied with 10 meters of output cable which is already terminated to suit the HVA60 test system. The TD60 is supplied complete with operating software which gives a complete picture of the tan delta measurement together with a real time display of the output voltage and current. The data transmission to the note book pc or PDA is via Bluetooth thus eliminating a direct connection between the TD60 and the data collection device.