Detailed Description
What Is a Motor Transmission Cable?
A motor transmission cable carries power from the drive to the motor — and, in modern servo installations, also carries the auxiliary circuits that the motor needs to operate safely: the holding brake and the temperature sensor. Where a plain motor power cable carries only the three phases and PE, a motor transmission cable integrates all of these circuits into one flexible, drag-chain-rated assembly.
Typical construction for a servo motor with holding brake:
- 3 power cores (U, V, W) + 1 PE — the 0.6/1 kV power path from the drive output stage to the motor stator
- 2 brake cores — 24 V DC supply for the electromechanical holding brake, typically 0.75–1.0 mm²
- 2 sensor cores — PTC thermistor or KTY temperature sensor signal back to the drive's monitoring input
Motor Transmission Cable vs Motor Power Cable — When to Choose Which
| Requirement | Motor Power Cable | Motor Transmission Cable |
|---|---|---|
| Motor without brake or sensor | ✓ | ✓ (unused auxiliary cores) |
| Motor with holding brake | Requires separate brake cable | ✓ — brake cores integrated |
| Motor with PTC/KTY temperature sensor | Requires separate sensor cable | ✓ — sensor cores integrated |
| Single-cable routing in drag chain | ✗ (auxiliary circuits missing) | ✓ |
| Maximum power cross-section | Up to 35 mm² | Up to 16 mm² |
| Drag chain space saving vs separate cables | — | 25–35% smaller bundle |
For motors with holding brakes — the majority of servo motors on CNC machines, robots, and packaging equipment — the motor transmission cable eliminates two separate auxiliary cables and their connectors. Fewer connectors mean fewer failure points, simpler cable management, and less drag chain space.
Integrated vs Separate Brake and Sensor Cables — Practical Comparison
| Factor | Separate Cables (3 total) | Integrated Transmission Cable (1 total) |
|---|---|---|
| Cables in drag chain | 3 (power + brake + sensor) | 1 |
| Connectors per motor | 3 pairs | 1 pair |
| Failure points | More | Fewer |
| Drag chain compartments | 2–3 | 1 |
| Installation time | Higher | Lower |
| Cable OD (comparable setup) | 3 × 6–10 mm | 1 × 12–18 mm |
| Replacing a damaged cable | Replace only the failed one | Replace all circuits at once |
Application Analysis: Where Motor Transmission Cables Deliver Value
- CNC machine servo axes: Axis servo motors with holding brakes are the standard configuration on CNC machining centers. The integrated cable simplifies the bundle that follows each axis in the drag chain
- Robotic drive motors: Space inside robot arms is extremely limited. Combining power, brake, and sensor circuits in one compact cable reduces routing volume and weight on the moving arm
- Packaging and indexing machines: Indexing drives with brakes stop precisely between cycles. The integrated brake cores switch the 24 V DC holding brake without a separate brake cable run
- Vertical axes and gantries: Vertical servo axes use holding brakes to prevent gravity drift when the drive is de-energized. A single transmission cable supplies power, brake, and thermal monitoring
- Conveyor and material handling: Servo-driven conveyors and transfer units with brakes benefit from reduced cabling and connection points across long machine lengths
Why Choose Yichi Motor Transmission Cables
- True integrated construction: Brake and sensor cores are stranded into the same concentric assembly as the power cores — not a bundle of separate cables under one jacket — giving a true single-cable cross-section
- Auxiliary cores engineered for their duty: Brake cores sized for 24 V DC holding-brake current; sensor cores optimized for PTC/KTY signal integrity with color coding per your drawing
- VFD-compatible power path: TPE insulation rated 90°C and 3 500 V AC test voltage, matched to the requirements of PWM inverter output
- Drag-chain validated: 10+ million flex-cycle endurance testing confirms both power and auxiliary circuits survive continuous machine motion
- Custom configurations: Specify any power cross-section, brake and sensor core count, shield option, jacket material, or drive-brand-specific layout — we manufacture to your exact drawing with full test certification