What is generally used to read more than the maximum of a maximeter scale?

A multiplier is used to read more than the maximum of a maximeter scale. This device allows for the scaling-up of an input signal so that it can be accurately represented and measured beyond the limit of the standard measurement scale. Essentially, it increases the range of the instrument measurement, enabling users to analyze higher values without the risk of damaging the instrument or obtaining inaccurate readings.

In the context of this question, a multiplier functions by modifying the relationship between the input and output values, effectively extending the scale's capability while keeping the original readings intact. This is crucial for linemen and others in the electrical field, where measuring higher voltages, currents, or powers is often necessary for diagnostic and operational purposes.

The other options relate to different electrical functions that do not specifically address the need to extend the effectiveness of a measurement scale. A booster generally amplifies a signal, a multiplexer combines multiple signals but does not extend measurement ranges, and a transformer changes voltage levels but isn’t meant for scaling a measurement directly.