FAQ - Frequently Asked Questions

What changed for contact wire selection after TB/T 2809-2026?

TB/T 2809-2026 removed pure copper contact wire grades and added CuCrZr (CTCZ). Sourcing and tender implications explain...

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Which standards do TB/T 3111.1-2026 and 3111.2-2026 replace?

TB/T 3111 split into two parts in 2026: Part 1 replaces 3111-2017, Part 2 replaces 2937-1998. What changed for messenger...

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Do in-service components built to old standards need replacement?

In-service OCS components built to old standards need no replacement; the 2026 editions apply to new procurement. Transi...

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Which current standards apply to section insulators and phase insulators?

Section insulators follow TB/T 3036-2016 and phase insulators follow TB/T 3037-2002.

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Why copper-alloy contact wire instead of pure copper?

Why OCS contact wire uses copper alloys: the strength-vs-conductivity trade-off behind CTA/CTM/CTS/CTCZ grades and the r...

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How does GB/T 25020.1-2025 relate to the earlier steel pole standards?

GB/T 25020.1-2025 took effect on 1 August 2025 and consolidates GB/T 25020.1-2010, 25020.3-2016 and 25020.4-2016 into on...

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What do contact wire designation letters CT, CTA, CTM, CTS mean?

Contact wire grade codes decoded: CT + alloy letter (A/M/S/CZ) + cross-section in mm², with CTAH/CTMH/CTS/CTCZ examples.

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Section vs neutral section insulator - what is the difference?

Section insulator vs neutral section insulator: same-phase segmentation vs inter-phase separation, structure, clearances...

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What is creepage distance in insulator selection?

Creepage distance explained and how pollution level drives insulator selection: porcelain vs composite, DC metro minimum...

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Do Chuangwit products carry CRCC certification?

Chuangwit holds CRCC railway product certification and ISO 9001; per-model certificate verification available for tender...

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What does a dropper do, and how do integral and adjustable droppers differ?

In a catenary suspension the dropper sets contact wire height, equalises elasticity and carries current.

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Do you support export and provide English technical documents?

Chuangwit supports export with English technical documents, bilingual support and standard cross-referencing for oversea...

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What does an OCS tensioning device do, and how do I choose between pulley, ratchet and spring types?

An OCS tensioning device keeps contact wire and messenger wire tension constant as temperature makes the conductors expa...

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How do I get a quotation quickly?

How to get an OCS component quotation from Chuangwit: email, WhatsApp or contact form with model, quantity, standard and...

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Which parameters matter when selecting a 27.5kV OCS disconnector?

For a 27.5kV disconnector (rated voltage matching the 25kV industrial-frequency traction supply system) four items need ...

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What types of OCS pole are there and where is each used?

OCS poles fall into four types: H-section steel poles, strong and in a small footprint, the mainstream choice for high-s...

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How do outgoing inspection and the warranty policy work?

Products are delivered after passing three levels of inspection: incoming re-inspection of raw material…

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What are your minimum order quantity and lead time, and do you customise?

Standard parts can be ordered in small batches or even singly; assemblies such as section insulators…

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What is the wear limit for contact wire?

Contact wire wear limits: ~25% average wear triggers full anchor-section renewal; local wear uses alert/limit levels; re...

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How far apart are droppers spaced?

Dropper spacing practice: uniform within a span, generally

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