What is a Slip Ring?
A slip ring is a device used to transfer electrical power and signals from a stationary to a rotating structure. It is an electrical connector that allows the rotation of a machine while still providing a continuous electrical connection. Slip rings are commonly used in CT scanners, where they are used to transfer power and signals from the stationary part of the scanner to the rotating part.
How Does an Induction Motor Work?
An induction motor is an electric motor that works by inducing an electric current in the rotor, which then creates a magnetic field that interacts with the stator to produce torque. This type of motor is commonly used in CT scanners, as it is able to provide the necessary power to rotate the scanner.
The Role of the Slip Ring and Induction Motor in CT Scanners
The slip ring and induction motor are essential components of a CT scanner. The slip ring is used to transfer power and signals from the stationary part of the scanner to the rotating part, while the induction motor is used to provide the necessary power to rotate the scanner. Together, these two components allow the scanner to rotate and acquire the necessary images for diagnosis.
Slip Ring Technology in CT Which Generation? In modern CT scanners, slip rings and induction motors work synergistically to enable continuous, high-speed gantry rotation. The induction motor provides the precise, high-torque mechanical drive to spin the heavy gantry assembly (housing the X-ray tube and detectors) at velocities exceeding 200 RPM. Simultaneously, the slip rings—electromechanical contacts bridging rotating and stationary components—transmit electrical power to the motor and X-ray tube, while relaying real-time detector data and control signals. This integrated system eliminates cable tangling, supports uninterrupted 360°+ rotation, and is foundational for helical scanning, rapid acquisitions (e.g., cardiac CT), and advanced imaging techniques in all slip ring–equipped generations (Gen 3 onward).
CT scanner slip ring diagram：Operating on principles akin to an induction motor, the CT slip ring system establishes a dynamic electromagnetic interface where stationary brushes (functioning analogously to a stator’s windings) induce current flow across an air gap into rotating conductive rings (acting as a secondary circuit). This contactless energy transfer mechanism — governed by electromagnetic induction rather than physical commutation — efficiently delivers high-frequency AC power for the X-ray tube’s anode drive motor and regulated excitation currents to gantry rotation motors, while simultaneously transmitting control signals and high-speed data through embedded fiber-optic channels. Unlike a traditional induction motor converting electrical to mechanical energy, this configuration leverages rotating magnetic flux principles to enable continuous mechanical rotation (0.3–4 RPM) by perpetually transferring power/data to the spinning gantry assembly, thereby eliminating cable fatigue and enabling artifact-free volumetric imaging.
Key Synergies:
Induction Motor: Drives gantry rotation (reliability/speed critical).
Slip Rings: Deliver power (to motor/tube) + transfer data (from detectors).
Result: Sub-second rotations, volumetric imaging, and dynamic studies.