Focusing on mode selection, a selector switch is the typical control used on operator panels. It provides several distinct, clearly labeled positions that stay in place until changed, so the current operating mode is always obvious to the operator. The physical detent and easy-to-read indication reduce the chance of accidental changes and support safe operation, sometimes even with optional interlock or lock features. While rotary switches can perform a similar function, selector switches are the standard choice specifically designed for selecting modes, offering quick, reliable mode changes at a glance. Pushbuttons are better for momentary actions like start/stop, and a keypad is for data entry, not straightforward mode selection.

Low-pass filters let through the low-frequency content and attenuate higher frequencies. This helps remove high-frequency noise and smooth a sensor signal, which is especially useful before digitizing the signal or when you only care about slow-changing phenomena. A notch filter, or band-stop filter with a very narrow stopband, specifically attenuates a narrow range of frequencies around a chosen frequency (like mains interference at 50 or 60 Hz) while leaving most of the spectrum intact. This is useful when you know a persistent interference is present at a particular frequency and you want to reject that specific frequency without harming nearby signal components. So, a low-pass filter is used to smooth and limit bandwidth by removing high-frequency noise, while a notch filter is used to suppress a particular interference frequency (mains hum) with minimal impact on the rest of the signal. The statement aligns with this: the low-pass removes high-frequency noise, the notch suppresses a narrow frequency like mains interference, and you apply a low-pass to smooth and a notch to reject mains interference.

Controlling how fast an actuator moves hinges on adjusting the flow of fluid reaching it. A flow control valve acts as a throttle: when you tighten it by turning clockwise, the opening shrinks, reducing the flow rate and therefore slowing the actuator. Turning it counterclockwise widens the opening, increases flow, and speeds things up. Upward or downward movement isn’t how you adjust a flow-control valve, so those directions won’t change the speed. So, to decrease actuator speed, rotate clockwise.

The essential idea in lockout/tagout safety is to physically prevent energy from reaching equipment while it is being serviced. To do this, each worker applies their own lock to the energy-isolating device, so only they can remove it and the equipment cannot be re-energized unexpectedly. A tag may accompany the lock to communicate that the equipment is out of service, but it does not by itself prevent energization. So, the item workers must have to prevent unexpected energization is a lock. Other safety items like badges, PPE, or permits support safety practices, but they do not stop the energy flow the way a lock does.