Certified Biomedical Equipment Technician (CBET) 2025 – 400 Free Practice Questions to Pass the Exam

The scenario where a centrifuge does not start without manual intervention on the rotor is often indicative of issues related to the rotor and its operation. Bad brushes in an electric motor can lead to insufficient contact with the rotor, preventing it from receiving the necessary power to initiate rotation. In many centrifuges, the motor's brushes play a critical role in conducting electricity to the rotor, and if they are worn out or malfunctioning, the motor may not receive the appropriate current to start cycling on its own.

Ensuring that the brushes are in good condition is vital for the proper functioning of the motor. If they are faulty, the centrifuge may stop or require manual assistance to engage, disrupting the operational workflow.

While other issues such as a faulty power supply or improper balancing can prevent the centrifuge from functioning as intended, they do not typically describe the need for manual intervention on the rotor itself. Overheating can also lead to shutdowns or failures but is more about the cessation of function rather than requiring manual intervention to initiate the process. Therefore, the relationship between motor activation and the condition of the brushes directly points to why the correct choice surrounds the concept of bad brushes.