Sometimes it is necessary to have several cables for each phase. For example, this happens when an overhead line (OHL) and a cable line are connected in series (see photos). Or it happens when we connect a transformer of a great power to the busbars (or consumers) using a cable line.

Cable connections of overhead lines and transformers usually have a short length of up to 500 meters. In such cases, it is recommended to use a single-end grounding of screens of single-core XLPE insulated cables.

Electrical “link boxes” are usually installed in the places where the screens are ungrounded. Surge arresters are placed inside the boxes to limit the impulse voltages between the cable screen and the ground, that is on the outer sheath of the cable. Such arresters are called sheath voltage limiters (SVL).

If we have several cables per phase, then the question arises – what is the best way to make a single-end grounding of the screens? How many boxes and how many SVLs do we need?

The photo shows an example when a box was equipped with three SVLs inside. Two cable screens came to each SVL at once:
✅SVL (A) to protect the sheath of cables A1, A2
✅SVL (B) to protect the sheath of cables B1, B2
✅SVL (C) to protect the sheath of cables C1, C2

Of course, the box was originally with a lid, but it was removed to take photos of the connections inside the box.

When switching the line and during lightning discharges into the overhead section of the line, such SVLs were subjected to increased energy (since each SVL is for two cables at the same time). As a result, SVLs were damaged.

Choosing the energy capacity of SVL and the operating voltage of SVL is not the easiest task. It is not always possible to install standard SVLs offered by the cable box supplier.

For cable lines of 110 kV and above, I personally would advise installing SVL with the following characteristics:
✅line discharge class according to IEC: at least 2nd class;
✅operating voltage: at least 6 kV (not 5 kV and of course not 3 kV).

It is shown in Chapter 10.3 of the book.