The size of the electronic and electrical gear is diminishing day by day acquiring the requirement for wires of more smaller size with the goal that they can be obliged in reduced space in the equipment. In high voltage applications if the size of the conductor is decreased the corona (ionized release) is delivered. This corona assaults the protection and significantly decreases the existence of insulating material. Subsequently to dodge the harm of insulation, the conductor size must be kept big which in turn limits the miniaturization process of the equipment. High voltage corona resistant cables (HVCR) eliminate this issue.
The HVCR cables are a significant advancement in technology and are recommended for "potentially" high risk applications. These cables offer assured reliability, long life at high temperatures and voltages with significantly smaller diameters and weights.
The test procedure and specs for HVCR cables are briefly described here. There are no generally accepted specifications for HVCR wires & cables. The test methods described here are based on long experience and specifications are proprietary.
On 100% length, 15 minute water soak, and water tank tests:
Dielectric Test at Working Voltage (WV) + 10% + 1 KV; duration 5 minutes (e.g. for WV 10 KV AC/22.5 KV DC, test will be at 12 KV AC)
Spark Test at AC using the value of KV DC rating for One Second,(e.g., for above type, 22.5 KV AC for one second).
Conductor dia and Resistance, and visual/OD check of finished cable.
On samples, Progressive Stress Test (PST) on 0.6 metre samples from both ends of each piece (and identified):
On these samples, AC voltage is applied in water tank test, starting at 1 KV and step-increasing by 2 KV at the end of each minute until break-down. Time and voltage are noted, and the range/spread recorded. BD Time should be above the minimum specified in the Figure for each piece. Average of all values should be well above the minimum specified.
For internal information and control, BDV on samples on AC is obtained and recorded.
|Voltage rating||4 KV to 22 KV AC|
|Conductor size||AWG 28 to AWG 10|
|Insulation||Corona resistant PTFE|
|CR insulation thickness||0.5mm - 2.5 mm (X 2 CR* to X 10 CR)|
|Operating temperature||Cryogenic rated to +260°C|
|Corona resistant life||10,000 hours|
|Jacketing color||Solid colors are standard.|
|Conductor material||Silver-plated copper, Nickel Plated Copper.|
*X 2 CR means minimum CR PTFE Wall Thickness 0.020" (0.5mm)