Which component is not associated with the mercury system's operation?

The component that is not associated with the mercury system's operation is the time delay relay. Mercury systems typically utilize components like mercury switches, float switches, and pressure switches to regulate and control various operational functions.

Mercury switches are widely used in these systems due to their ability to respond to changes in position and orientation, allowing for precise control in applications such as tilt and level sensing. Float switches are also integral, as they help monitor liquid levels while responding to buoyancy changes in the fluid being measured. Pressure switches further complement the system by sensing pressure changes and triggering actions based on pre-set thresholds.

In contrast, time delay relays are primarily used in applications where a delayed response is needed after an event, such as turning on a device after a specific period. They manage timing functions rather than the direct sensing of position, level, or pressure, which are core to the operations of mercury systems. Therefore, a time delay relay does not play a role in the fundamental functioning of a mercury system.