15 kV 45 Degree Terminations 1

[ThePunisher]

We have a case at site where the the 100:5A, C20, ABB BYZ-S ZCT window was accommodating 2 per phase power cables and due to the window size the phase A and Phase C cannot be terminated vertically straight but are naturally self-bending towards their terminals at almost 45 deg angle.

We thought of using a UL/CSA Listed 45 Deg-angled terminal block. We got confirmation from our switchgear vendor that the ZCT is fine. I have got our construction folks to measure the clearances using the angled terminal blocks and the clearances are still ok plus the terminations will be covered with additional re-usable insulating boots.

I do not see any issues using the 45 Deg terminals as it matches the natural bend of the cable cores.

Does anyone have any comment or experience using 45 Deg terminal lugs at 13.8 kv switchgear at the same circumstances. We were intending to get the ZCT replaced with a rectangular one (ABB BYZ-L) which have a 8" x 20" window but the delivery date and procurement process won't make it at this point.

Regards,

 

[cuky2000]

The 45^o degree termination is commonly used in the industry.
The major potential concern you already addressed that is the connector phase-to-phase clearance appears to be less than the insulated bus clearance. Just to be on the safe side, double checks the clearance and tries to properly insulate the bear portion of the connector to avoid being the weakest link in the event of flashover.

 

[ThePunisher]

Thanks Cuky2000. What is industry standard phase-phase and Phase-Ground electrical clearances for 13.8 kV nominal system voltage? I am thinking NESC but I am in Canada and am looking what CSA standard would that be.

Or I would be relying on the switchgear measurements between bus terminals.

Regards,

 

[cuky2000]

Most of the industry-standards alow the manufacturer freedom to choose values appropriate to the product design and manufacturing process including the bus clearance provided that the product must pass the design (type) tests in the respective standards associated with the impulse withstand (BIL) and power frequency withstand.

The clearances per NESC and IEEE C57.12.00 are applicable to the external live parts exposed to the weather. Below is a chart with usual values used in the industry for bus clearance for MV switchgear inside the enclosure and external clearances per the NESC and IEEE Std for reference.

Since testing the switchgear and cable is not a practical option, check if is possible to insulate the portion of the bare connectors with insulation at least the same or larger than the switchgear bus insulator.

_{NOTE: The dielectric performance of the equipment is affected by a great many factors, including distance between conductors, and to the enclosure, shape of the conductors and adjacent conductive elements including those of the enclosure Insulation, if any, on the conductors Atmospheric conditions, including atmospheric pressure and humidity cleanliness of the equipment and aging of insulation.}

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