Which instrument is best suited for measuring high values of resistance?

The best instrument for measuring high values of resistance is a megohmmeter. This tool is specifically designed to measure resistance in the megohm range, which is significantly higher than what typical multimeters or ohmmeters can measure. Megohmmeters operate by applying a high voltage to the resistance being tested, allowing for accurate measurement of insulation resistance in electrical equipment, cables, and other components where high resistance is expected.

While multimeters and ohmmeters can measure resistance, they are generally not suitable for high resistance values because their measuring capabilities are limited to lower ranges (usually up to a few megaohms in the case of advanced multimeters). In contrast, an ammeter is not used for measuring resistance at all; it is designed to measure current flow in a circuit. Therefore, for applications requiring the measurement of high resistance, particularly in testing electrical insulation, a megohmmeter is the ideal instrument.