What are the methods to reduce the secondary load of the current transformer?

1. Choose a suitable secondary cable:
Reduce the cable length: When the secondary cable is long, its resistance will increase, resulting in an increase in the secondary load. Therefore, the length of the secondary cable should be shortened as much as possible to reduce the secondary load. For example, install the current transformer close to the measuring instrument or protection device, or use cable trays and other methods to reduce the laying length of the cable.
Increase the cable cross-sectional area: The resistance of the cable is inversely proportional to the cross-sectional area, so increasing the cable cross-sectional area can reduce the cable resistance, thereby reducing the secondary load. For example, replace the original cable with a smaller cross-sectional area with a cable with a larger cross-sectional area, or add parallel cables to the original cable to increase the total cross-sectional area of ​​the cable.
2. Optimize the connection method of the secondary circuit:
Reduce the connection points: The more connection points in the secondary circuit, the greater the contact resistance, which leads to an increase in the secondary load. Therefore, the connection points in the secondary circuit should be minimized to reduce the secondary load. For example, use welding or crimping to connect the secondary cable, and avoid using bolt connections and other methods.
Ensure the quality of connection: The contact resistance of the connection point is closely related to the quality of connection, so the contact of the connection point should be ensured to reduce the secondary load. For example, when connecting the secondary cable, ensure that the surface of the cable connector is clean and flat, and use appropriate connection tools for connection.
3. Use low-power measuring instruments and protection devices:
Choose appropriate instruments and devices: Different measuring instruments and protection devices have different power consumption, so instruments and devices with lower power consumption should be selected to reduce the secondary load. For example, choose digital instruments or intelligent protection devices, which usually have lower power consumption.
Reasonably set the parameters of instruments and devices: Some measuring instruments and protection devices can adjust their power consumption by setting parameters, so these parameters should be set reasonably to reduce the secondary load. For example, reduce the sampling frequency of the instrument or the action current of the protection device, etc.
4. Increase the transformation ratio of the current transformer:
Calculate the transformation ratio: The transformation ratio of the current transformer refers to the ratio of the primary current to the secondary current. Increasing the transformation ratio of the current transformer can reduce the secondary current, thereby reducing the secondary load. For example, if the original 100/5A current transformer is replaced with a 200/5A current transformer, the secondary current will be reduced by half, and the secondary load will also be reduced accordingly.
Note: Increasing the ratio of the current transformer requires recalibration of the parameters of the measuring instrument and protection device to ensure its accuracy and reliability. At the same time, it is also necessary to pay attention to whether the capacity of the current transformer meets the requirements to avoid overload.
5. Use secondary load compensation device:
Working principle: The secondary load compensation device is a device specially used to reduce the secondary load of the current transformer. Its working principle is to inject a compensation current equal to the secondary current and opposite in direction into the secondary circuit to reduce the secondary load.
Advantages: The secondary load compensation device can effectively reduce the secondary load of the current transformer and improve the measurement accuracy and protection performance. At the same time, it can also be flexibly adjusted according to actual conditions to adapt to different load changes.