The study of vibration reliability of grounding current collectors for propeller shafts in azimuth thrusters

An azimuth thruster (AT) is a key component of a ship’s electric propulsion system, providing both thrust and maneuverability. The AT integrates a propeller-driving motor with a steering mechanism. Grounding systems and condition monitoring are employed to protect the propeller shafts and propellers from electrochemical corrosion. Current collectors equalize the electrical potential between the shaft and the hull, preventing corrosion, but they are susceptible to vibrations generated during ship operation. These vibrations can disrupt the operation or cause failure of the current collectors.

This paper analyzes the vibration reliability of current collectors developed by JUVTEK LLC for Ats installed on high ice-class vessels. Tests conducted on a vibration test stand at NPO СKTI JSC evaluated the strength of the brush holders and the brush-shaft contact stability under various vibration levels. The research demonstrated that vibrational loads are critical to the reliable operation of the current collectors.

The tests included monitoring contact resistance under vibration at amplitudes of ±2.3 mm and ±3.3 mm in the frequency range of 2–100 Hz. The contact remained stable, but at frequencies above 130 Hz, disruptions occurred due to resonance. Critical frequencies affecting device reliability were identified. Recommendations for design improvements are proposed, including adjusting brush spring pressure and modernizing the brush holder bracket. 

1. GOST R 51780-2001. Ship Control Systems. General Requirements for Design and Testing. – Moscow: Standards Publishing House 2001: 24.

2. A new technology will protect ship propellers from corrosion [Electronic resource] / A. V. Brezhnev. Access mode: https://www.korabel.ru/news/comments/novaya_tehnologiya_zashchitit_grebnie_vinti_sudov_ot_korrozii.html (date of access: March 27, 2023).

3. Russian Maritime Register of Shipping. Rules for Classification and Construction of Sea Vessels, Part VII Mechanical Installations. 2022.

4. Laboratory of Vibration Reliability of Blade Apparatus [Electronic resource] / CKTI. Access mode: https://ckti.ru/laboratoriya_vibracionnoi_nadeznosti_lopatochnogo_apparata.html (date of access: March 27, 2023).