Comparison
How each termination technology grades the electric field
One axis only: what holds the field down where the cable screen is cut back, and how much of that mechanism is decided on site.
Three grading systems, one catalogue
Five inputs decide this: insulation type, core count, mm², Umax, and indoor or outdoor. Torch access, shelf handling and install time are absent below, because no comparative figure for any of them is published.
| Grading system | What actually grades the field | What is decided on site | Published ceiling |
|---|---|---|---|
| Discrete stress control tube (GXO/E, GPO/E, GXOS/E kits) | A radiation cross-linked tube shrunk over the screen cut edge, with stress control mastic filling the step | Position, overlap and void filling, by the jointer | 36 kV |
| Integrated coating (Soloterm; GVOT sleeve) | A varistor coating bonded to the cable insulation and screen from within the termination body | Nothing — the grading layer arrives already bonded to the component | Soloterm 33 kV; GVOT sleeve 36 kV on its datasheet, 24 kV on the component list |
| Screened separable connector | A moulded stress-cone adapter, with an earthed outer conductive screen bounding the field at earth potential | Adapter choice against cable cross-section; the body is plugged, not built | 630 A to 24 kV; 630/1250 A to 36 kV |
Discrete grading: a component someone has to place
In the GXO/E, GPO/E and GXOS/E kits the field grading is a separate line on the packing list. Insultube-Stress is a radiation cross-linked polymeric tube formulated for the high stress present at an insulation-screen terminal, published up to 36 kV.
It begins shrinking at 100°C and is fully recovered at 130°C, over a service range of -40°C to 100°C. Standard colour is black. Material properties are published against [ASTM D638], [ASTM D2671] and [ASTM D2240].
The tube alone does not finish the job. A void left at the semi-con step concentrates field precisely where the tube is meant to relieve it, which is why the single-core GXOS/E-1236 kit lists stress control mastic beside the stress control sleeve. On the GXO/E kits, temperature-sensitive paint changes colour when recovery is complete — a check on heat delivered, not on where the tube sits.
Placement is therefore the exposure. Overlap onto the screen, overlap onto the insulation and the filling of the step are all set at the bushing, and none of them stays visible once the non-tracking sleeve is down over it.
Integrated grading: the coating is part of the body
Soloterm moves the mechanism inside the component. Its integrated varistor stress-control coating bonds to the cable insulation and to the screen from within, blocks moisture ingress, and seals to the cable lug. Stress control, insulation and moisture sealing arrive as one compact termination with few components.
One published consequence is worth reading twice: because the stress-control system is built in, indoor terminations need no separate sheds. That claim is scoped to indoor work.
Published scope is polymeric cable, indoor and outdoor, up to 33 kV — three kV below the ceiling of the discrete-tube kits. Other listed properties are no shelf-life limitation, UV resistance and range taking, per the manufacturer's Soloterm page.
A third heat-shrink variant sits between the two: the GVOT integrated stress control sleeve, cross-linked polyolefin with an integrated varistor stress control system, published in six sizes from GVOT 30/12 to GVOT 85/32 on internal diameter. Its own datasheet describes it as an integral part of Gala cable terminations up to 36 kV; the manufacturer's components list puts the same sleeve at 24 kV. Which kit codes ship it instead of a discrete tube is not stated in any source available here.
Bounded grading: the screened separable connector
This is the only one of the three where grading and touch-proofing are the same part. A moulded stress-cone adapter shapes the field, and an earthed outer conductive screen bounds it at earth potential rather than letting it run out along a surface in air.
The body is highly modified EPDM rubber. One body plus stress-cone adapters covers 25 to 400 mm² up to 24 kV and 95 to 630 mm² at 36 kV, and every kit includes multi-range compression lugs matched to the connector.
The screen is a specified quantity, not a finish: screen resistance is published at ≤5000 Ω and partial discharge at 1.73U0 at ≤10 pC [IEC 60502.4]. The body mates with type C bushings to EN 50180 and EN 50181, so the switchgear decides the interface before the cable does. Full geometry sits on separable connectors.
It is also the only option not built up on the cable at the bushing, and the only one factory tested unit by unit for AC withstand and partial discharge before dispatch.
Cold shrink is not one of the three
Two cold-shrink items are catalogued — a breakout and a tubing, both EPDM rubber free of chloride and sulfur — and neither is a termination. The heat-shrink against cold-shrink comparison, with the datasheets behind it, is held at shrink-tube.com — a sister reference from the same publisher as this site, not an independent source.
Where each set of inputs lands
Read your own cable schedule row against these. Each line resolves to one page, not to a range.
- 3-core XLPE or EPR, 12 to 36 kV, landing on a lug — discrete grading. Stress control tubing is a named item in the XLPE kit component list.
- PILC — discrete grading only. The GPO/E kits pair the stress control sleeve with an oil barrier sleeve and an earthing plumb, and the integrated system is published for polymeric cable.
- Indoor polymeric termination where sheds are unwelcome — the integrated coating, which is published as needing none indoors.
- A type C bushing rather than a lug, or a touch-proof requirement — the separable connector, because the earthed screen is doing both jobs at once.
- 1.1 or 3.3 kV — no grading system at all. The GLT-1100 kit contains no stress control item; there is nothing at that class for a tube to relieve.
- Above 36 kV — nothing in this catalogue. The termination range stops there, as set out on the 36 kV limit.
Not published — ask the manufacturer
No comparative installation time, failure rate or cost figure exists for these three systems in any source used here, and none is estimated on this page. Also absent: which kit codes ship the GVOT sleeve rather than a discrete tube, and any published account of how the varistor coating behaves once the cable has aged. The permittivity is no longer on this list — the manufacturer publishes a dielectric constant of 15 minimum [ASTM D150] for the stress control tube, which is the figure the whole grading argument rests on. It is set out on grading the field at the screen cut-back.
Sources disagree
The separable connector is scoped two ways in the manufacturer's own page. Its title and description say up to 24 kV at 630 A; the body text and the specification table on the same page carry a second variant at 630/1250 A up to 36 kV. Both are reported here as published. Confirm the variant in writing before a 36 kV requisition.
Questions this comparison raises
What does "dry type" mean on a heat shrinkable termination?
Is a pre-moulded termination the same as a plug-in termination kit?
Does the integrated coating remove rain sheds outdoors as well?
Which of the three is most reliable in service?
Can the grading choice be corrected once the kit is on site?
Send five inputs, get one kit code back
Insulation type, core count, mm², Umax, indoor or outdoor, plus the bushing interface if there is one. That settles the grading system and the kit code in one reply.