Time:2026-07-30 Browse: 5
Current transformers (CTs) are primarily used in three key areas: power metering, relay protection, and operational monitoring. For metering applications, high-accuracy CTs rated at 0.2 or 0.5 class should be selected to ensure accurate electricity billing. In protection applications, protective-grade CTs such as 5P or 10P with strong anti-saturation capability are required to guarantee reliable operation during short-circuit faults. When selecting CTs, the turns ratio should be determined based on 1.2 to 1.5 times the primary rated current, so that under normal operation, the instrument readings remain around two-thirds of full scale, thereby ensuring measurement accuracy. During installation and use, the primary winding of the CT is connected in series within the main circuit, while the secondary winding is connected in series with instruments to form a nearly short-circuited operating condition. It is essential to strictly follow two critical safety principles: never open-circuit the secondary side and ensure single-point grounding, to prevent electric shock and equipment damage, thus ensuring safe and stable operation of the power system.
