Your cookie settings. Personalised experiences at full control.
This website uses cookies and similar technologies (“cookies”). Subject to your consent, will use analytical cookies to track which content interests you, and marketing cookies to display interest-based advertising. We use third-party providers for these measures, who may also use the data for their own purposes.
You give your consent by clicking "Accept all" or by applying your individual settings. Your data may then also be processed in third countries outside the EU, such as the US, which do not have a corresponding level of data protection and where, in particular, access by local authorities may not be effectively prevented. You can revoke your consent with immediate effect at any time. If you click on "Reject all", only strictly necessary cookies will be used.
Views: 50 Author: Violin Publish Time: 2026-09-19 Origin: Site
Cold Shrink Termination Winter Cracking, Cable Grounding & Serpentine Laying: 3 Technical Q&As Every Cable Engineer Should Know
Reliable power connections start with the right technical decisions. In this article, NKS POWER answers three high-frequency questions about cable accessories — cold shrink termination cracking in winter, sheath circulating currents in long cables, and cable length allowance — with data and engineering essentials.
Q1. Why Do Cold Shrink Terminations Crack in Winter? The Data Behind It
Silicone rubber cold shrink terminations are designed for an operating range of -65°C to +90°C, and the material itself stays flexible down to -65°C. But the real risk is not the operating temperature — it's the installation.
Three Key Parameters
Parameter
Requirement
Notes
Installation ambient temperature
≥ 5°C
Below this, retraction force drops noticeably
Low-temperature pre-conditioning
When ambient < 5°C, store accessories at ≥ 15°C for at least 4 hours
Restores full elastic recovery
Core rod removal speed
0.5–1 m/min
Pulling too fast causes stress concentration — the #1 cause of cracking
The Cracking Mechanism
For every 10°C drop in temperature, silicone retraction force decreases. Below 0°C, elastic recovery slows significantly. If the termination is installed without pre-heating, it may not shrink completely, causing uneven interfacial pressure, which leads to partial discharge — and eventually cracking or seal failure.
NKS POWER cold shrink terminations are made from high-elasticity liquid silicone rubber and pass low-temperature recovery testing, validated for service down to -65°C. Cold weather should never compromise your power connection.
Q2. Why Can't Long Cables Be Grounded at Both Ends?
Grounding both sheath ends creates huge sheath circulating currents — up to 30%–80% of the conductor current — causing cable overheating, reduced current-carrying capacity, and accelerated insulation aging.
The Solution: Cross-Bonding (Section Transposition)
Divide the long cable into three equal sections, with an insulating joint between each section, then "transpose" the three-phase sheaths in a loop:
Phase A sheath end connects to Phase B's head
Phase B tail connects to Phase C's head
Phase C tail connects to Phase A's head
The three sections induce voltages of equal magnitude, 120° apart — they cancel each other out to nearly zero. The circulating current disappears, the sheath stops heating, and the cable's transmission capacity is restored.
Engineering Essentials
·Applies to long cables typically over 2–4 km
·The three sections must be equal in length, tolerance within 5%
·Both ends are directly grounded
·Sheath voltage limiters are installed in the cross-bonding box
Q3. Why Are Cables Laid in a Serpentine Pattern? Why Order 5–10% Extra Cable?
The calculated length seems sufficient — so why do engineers still order 5%–10% extra? The answer combines engineering standards and field experience (per GB 50217-2018).
Where Does the Additional Length Come From?
Factor
Allowance
Unusable remaining sections from whole cable drums (≤ 35kV, non-long-distance)
5%–10% of calculated length
Sag, wave curves and crossings in trays and ducts
2.5% of total cable length
Bending allowance for serpentine laying (≥ 35kV)
Required for thermal movement
Fault repair — cutting out damaged sections and re-jointing
Reserve length
Why Serpentine Laying?
Cables expand when energized and contract when de-energized — cycling through thermal expansion and contraction repeatedly. Serpentine (snake-shaped) laying absorbs this thermal movement, preventing mechanical stress from concentrating at joints and terminations. For 35kV and above, this bending allowance is a mandatory design consideration.
The Cost of Coming Up Short
When a cable fault occurs, the damaged section must be cut out and re-jointed. If the remaining length isn't enough, the whole drum may need to be scrapped and replaced — a huge cost in materials, labour and downtime.
Choose Accessories You Can Trust, in Any Climate
From -65°C cold shrink terminations to long-distance cable systems, NKS POWER offers a full range of MV & HV cable accessories — cold shrink terminations, joints, separable connectors, busbar connectors and surge arresters — manufactured to international standards and validated by independent KEMA type testing.
Need help selecting the right cable accessories for your project?
Contact NKS POWER — we support you from specification to installation.
NKS Power adheres to the concept of environmental friendliness and smart connection, and is willing to work with you to create green and sustainable development, leading smart technology power industry.
