How are contact wire types distinguished, and what is the selection principle?
Contact wire types are designated by alloy class, strength grade and nominal cross-section: CT is pure copper, CTA copper-silver, CTS copper-tin, CTM copper-magnesium and CTCZ copper-chromium-zirconium. Henan Chuangwit supplies full cross-section ranges of CT, CTA/CTAH, CTS, CTM/CTMH and CTCZ/CTCZM contact wires — the CT series covers CT65, CT85, CT100, CT110, CT120 and CT150, while CTA/CTAH covers CTA85, CTA110, CTA120, CTA150 and the corresponding CTAH types. The core of selection is the balance of strength, conductivity and heat resistance; the higher the conductivity, the better the current capacity and voltage-drop performance.
For high-speed lines, should pure copper or copper alloy contact wire be chosen?
Pure copper contact wire suits conventional and speed-raised lines: the Chuangwit CT series is rated up to 200km/h with at least 97% IACS conductivity under GB/T 12971.1-2023. High-speed sections should use copper alloy contact wires — CTM/CTMH copper-magnesium contact wires are rated CTM up to 250km/h and CTMH up to 350km/h, and CTCZ/CTCZM copper-chromium-zirconium contact wires are a new type in TB/T 2809-2026. CTCZM150 offers tensile strength of at least 560MPa with conductivity of up to 90% IACS, suited to high-speed large-tension contact suspensions.
How should messenger wire and contact wire be matched, and which messenger wire should be chosen?
The messenger wire is hung through cantilever insulators and connected in parallel with the contact wire via electrical connections, so it also carries current; its selection should match the contact wire alloy system. The Chuangwit JT hard copper stranded wire range covers JT70, JT95, JT120 and JT150 with at least 97% IACS conductivity under TB/T 3111.1-2026, suitable as messenger wire and auxiliary suspension conductor. For high-speed and speed-raised lines choose JTM/JTMH copper-magnesium stranded wires, with complete cross-sections from JTM10 to JTM150; JTMH is rated up to 350km/h.
How to weigh messenger wire ampacity against conductivity?
Messenger wires have large cross-sections and long spans, so conductivity directly determines DC loss and current-carrying margin. The Chuangwit JTCZ copper-chromium-zirconium stranded wire, a new type in TB/T 3111.1-2026, offers at least 87% IACS — 12 percentage points higher than JTMH — with JTCZ120 ultimate tensile force of at least 59.16kN and JTCZ150 of at least 72.68kN, rated up to 250km/h. JTM copper-magnesium stranded wire offers at least 80% IACS and JTMH at least 75% IACS, selectable by line tension and current collection requirements.
| Series | Key parameters | Standard |
|---|---|---|
| CT series (pure copper contact wire) | 65~150mm², at least 97% IACS, up to 200km/h | GB/T 12971.1-2023 |
| CTA/CTAH (copper-silver) | up to 250km/h | TB/T 2809-2026 |
| CTM/CTMH (copper-magnesium) | CTMH up to 350km/h | TB/T 2809-2026 |
| CTS (copper-tin) | up to 250km/h | TB/T 2809-2026 |
| CTCZ/CTCZM (copper-chromium-zirconium) | CTCZ at least 469MPa, CTCZM at least 560MPa | Added in TB/T 2809-2026 |
| JT, JTM, JTMH stranded wires (messenger wires) | 70/95/120/150 mm², JTM at least 80% IACS, JTMH at least 75% IACS | TB/T 3111.1-2026 |
| JTCZ (copper-chromium-zirconium stranded wire) | JTCZ120 at least 59.16kN, JTCZ150 at least 72.68kN, at least 87% IACS | Added in TB/T 3111.1-2026 |
| TJR (soft copper stranded wire) | for electrical connections / earthing / jumpers | GB/T 12970.2-2009 |
| LBGLJ (aluminum conductor with aluminum-clad steel core) | JL, LB1A series | TB/T 3111.2-2026 |
For railway projects choose copper alloy contact wires (TB/T 2809-2026 has removed the pure copper type); CTCZ and JTCZ parameters follow the draft-for-comment basis and the product pages carry a disclaimer note.
