[Core Summary]
When incremental encoders are used in high-rise elevators, the car position is lost upon mains power interruption, and restoring power supply requires returning to zero level by level, affecting rescue and re-leveling. Taking the high-rise elevator traction system as a typical example, a Fenac FNC series multi-turn absolute encoder (with CANopen interface) is deployed at the shaft end of the traction machine. The position is read upon power-on, eliminating the need for the return-to-zero process. (This article serves as a typical application reference, with specifications based on product data and not a specific project delivery commitment; actual accuracy is subject to the model datasheet.)
Background and Pain Points
The high-rise elevator originally used incremental encoders. After a mains power interruption or maintenance power shutdown, the actual position of the car is reset to zero. Upon restoration of power, a full-range homing process must be executed to find the floor, and the time taken for homing increases linearly with the number of floors [please verify].
The homing action itself occupies maintenance windows, resulting in a monthly loss of available operation time for construction site elevators that experience frequent power outages [please verify]. If the car stops outside the leveling zone at the moment of power outage, the rescue and re-leveling operations are constrained by the homing process, leading to low on-site handling efficiency. After multiple projects have reported the same issue, elevator manufacturers can consider "maintaining the power-off position and avoiding homing upon power-on" as a new solution for reference.
Solution and Deployment
Retrofit the Fenac FNC series multi-turn absolute encoder on the shaft end of the traction machine, with the interface selected as CANopen [please verify], directly connected to the existing elevator master controller. The multi-turn counting covers the cumulative revolutions of the traction sheave, ensuring continuous position readability throughout the elevator's travel, eliminating the need for mid-journey updates.
Deployment Key Points:
The coupling at the shaft end and the encoder flange are selected according to the original machine specifications to avoid mechanical modifications;
The bus address and master controller position mapping are written in one go, eliminating the need for reference points on each floor;
The car position is read immediately upon power-up, and the homing process is completely eliminated.
The FNC series multi-turn encoder adopts battery-free mechanical counting [please verify], avoiding position loss due to battery aging and the cost of regular replacement.
The on-site wiring continues to use the existing encoder cables, with only the addition of a CANopen coupling node at the control cabinet end [please verify]; the FNC multi-turn resolution is selected based on the traction ratio and floor accuracy requirements, with 13 bits for single turns and 12 bits for multi-turns [please verify], meeting the leveling repeat positioning requirements without blindly increasing the number of bits.
Results and Value (Indicative)
After the transformation, power-off recovery no longer relies on layer-by-layer homing, and the car position is readable in real time. Rescue and re-leveling actions are no longer restricted by homing. Both leveling accuracy and power-off recovery metrics meet expectations, and elevator manufacturers can incorporate the solution into their standard configuration checklist for reference.
This solution also reduces the workload of commissioning: a single position calibration is sufficient before shipment, eliminating the need for on-site layer-by-layer homing. Elevator manufacturers can include the FNC series in their recommended components list for long-travel elevator models and manage them by unified model in the spare parts inventory, reducing model fragmentation for later maintenance and replacement.
[Parameter Table] Typical Reference
The above is a typical reference range for similar elevator models. Specific accuracy and interface types are subject to the corresponding model documentation of the Fenac FNC series.
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