Instrument transformers convert high primary-side voltages into standard low voltages (e.g., 100V) or large primary currents into standard small currents (e.g., 5A or 1A), making them suitable for use with measuring instruments and protective equipment. For instance, a current transformer with a 400/5 ratio converts a 400A primary current into a 5A secondary current. In international standards, the secondary side of a voltage transformer is often 120V, while that of a current transformer is 5A or 1A.
Isolation Function
They provide electrical isolation between the high-voltage primary system and the low-voltage secondary equipment via electromagnetic coupling. This prevents high voltage from being transmitted directly to measuring equipment, thereby ensuring the safety of personnel and hardware. The primary winding connects to the high-voltage side of the grid, while the secondary winding connects to measuring instruments and protective devices, effectively separating the high- and low-voltage systems for safety.
Current Measurement: Instrument transformers can measure the magnitude of current flowing through a circuit, acting as current sensors; they are widely used in power system monitoring and electrical energy metering.
Voltage Measurement: Instrument transformers enable the measurement of circuit voltage, facilitating applications such as circuit status monitoring and fault diagnosis.
Power Measurement: By combining current and voltage measurements, instrument transformers allow for the calculation of power values within a circuit, serving purposes such as energy management and equipment monitoring.
Overload Protection: Incorporating instrument transformers into a circuit enables the monitoring of and protection against overload conditions, thereby preventing equipment damage and ensuring personal safety.