A CT & PT Polarity Tester, often referred to as a Current Transformer and Potential Transformer Polarity Tester, is an electrical testing device used to determine the correct polarity and connection of current transformers (CTs) and potential transformers (PTs) in power systems. These testers ensure that the CTs and PTs are installed correctly, preventing errors in electrical measurements and equipment protection. A miniature model may be a smaller, portable version of such a tester, suitable for specific applications or field testing