Detailed Description
Control vs Power — The Separation Argument
A combined elevator traveling cable carries both power conductors (1.5–2.5 mm² for car lighting, fan, door operator motor) and control conductors (0.5–1.5 mm² for signals) in one flat cable. This is the most common configuration for standard elevators — one cable, one installation, one set of terminations.
However, there are three reasons why a dedicated control traveling cable — separate from the power cable — is specified in certain applications:
1. Electrical Noise Isolation
A door operator motor draws 2–5 A at 220 V AC. When it starts and stops, it generates voltage transients that couple into adjacent conductors through parasitic capacitance. If these adjacent conductors carry the car call button signals — typically 24 V DC pulled up to 10 kΩ at the controller input — a transient can falsely trigger a floor call. A separate control cable, physically separated from the power cable in the shaft by 50–100 mm, eliminates this coupling path.
2. Modernization Flexibility
When modernizing an older elevator, the power requirements often change (new energy-efficient LED lighting replacing incandescent, new VFD door operator replacing AC motor). A separate control cable can remain in place while only the power cable is replaced — reducing modernization cost and downtime.
3. Controller Compatibility
Some elevator controllers — particularly older relay-logic and early solid-state controllers — require a specific core allocation and conductor cross-section that differs from the combined cable standard. A dedicated control cable can be specified to match the controller exactly, without compromise to accommodate power conductors.
Signal Allocation in a 24-Core Control Cable
A typical 24-core elevator control cable allocation for a mid-rise passenger elevator with collective-selective control:
| Signal Group | Cores | Cross-Section | Signal Type |
|---|---|---|---|
| Car calls (floor buttons) | 8 | 0.5 mm² | 24 V DC, common return |
| Door open / door close | 2 | 0.75 mm² | 24 V DC or 110 V AC |
| Door safety edge | 2 | 0.5 mm² | NC safety circuit, series loop |
| Floor position indication | 3 | 0.75 mm² | Binary coded or serial data |
| Car position (selector) | 3 | 0.75 mm² | Binary coded floor level |
| Intercom audio | 2 | 0.5 mm² | Analog audio, shielded pair |
| Inspection control | 3 | 0.75 mm² | Up/down/common |
| Spare | 1 | 0.75 mm² | Future use |
For CAN bus or serial communication elevators, 2–4 cores (0.5 mm²) are allocated to the data bus, typically with twisted pair construction for noise immunity.
Yichi Control Cable Manufacturing
- Conductor sizing matched to signal current: Control conductors are sized for actual signal currents, not arbitrarily oversized. A 0.5 mm² conductor safely carries 3 A — far more than the 10–100 mA typical of elevator control signals. Oversizing adds weight, increases cable dimensions, and contributes nothing to electrical performance
- Core numbering sequence logical for elevator wiring: Core numbers follow a logical grouping sequence (car calls grouped, door controls grouped, safety circuits grouped) rather than simple sequential numbering. This reduces wiring errors during installation
- Steel wire suspension elements corrosion-protected: Galvanized steel wires are additionally coated with a thin PVC or PE layer where they exit the cable jacket at the anchorage points — preventing corrosion at the most vulnerable point, the jacket-to-air transition
- Flame retardancy verified: PVC jacket compound tested per IEC 60332-1-2 on every production batch. The elevator shaft is a vertical fire propagation path — cable flame retardancy is a building safety requirement, not optional