6. emi instrument transformers (with marking)

Instrument transformers, namely current transformers (CT) and potential transformers (PT), are used to isolate measurement devices from high-voltage power systems. CTs sample current by having a primary winding connected in series with a circuit, producing a proportional current in the secondary for measurement. PTs sample voltage by connecting the primary across transmission lines, inducing a stepped-down voltage in the secondary. Both types isolate secondary measurement circuits while allowing proportional current or voltage monitoring for protection relays and metering equipment.