Which tool is commonly used to measure insulation resistance in electrical equipment?

The TTR (Transformer Turns Ratio) meter is specifically designed to measure the insulation resistance and turns ratio of transformers, making it highly relevant for assessing insulation quality in electrical equipment. It applies a voltage to the windings and measures the resulting current, allowing for a detailed evaluation of the insulation's effectiveness and the condition of the transformer.

In contrast, while ohmmeters measure resistance, they are not specialized for insulation applications where higher voltage is typically needed to effectively test insulation. Thermal cameras are used for detecting heat patterns and identifying issues like overheating, but they do not measure resistance or insulation properties. Clamp meters are designed to measure current without disconnecting cables; they do not assess insulation resistance. Thus, the TTR meter is the most appropriate tool for this specific measurement purpose.