How to maintain and care for a DP current transformer?

Method of maintenance and repair of DP Current Transformer:

Appearance inspection: Clean the exterior of DP Current Transformer regularly to prevent dust and dirt accumulation. Check if transformer casing is intact, damaged, cracks or deformed. Ensure that the terminal box is free of foreign objects to prevent discharge and cracking.
Connection check: check the terminal for any discoloration. Make sure the secondary circuit is well connected, corrosion free and polarity correct. Check the integrity of the secondary circuit to ensure that there is no open or short circuit. Tighten the fasteners to ensure that it does not loosen.
Operation status inspection: check for abnormal sound or odor during operation of current transformer. Be careful not to hear discharges or other noises coming from inside the transformer. Secondary instrumentation indicators related to transformers should be normal.

Calibration content: Regular calibration of DP Current Transformer in accordance with relevant standards and regulations. In general, a comprehensive calibration should be conducted every 3 to 5 years. Calibration includes testing of parameters such as ratio, polarity, phase, etc., to ensure that transformer performance meets requirements.
Insulation resistance test: Test insulation resistance regularly using standard resistors and ammeters to ensure the insulation performance of transformers. If the insulation resistance of a winding is less than 70% of the previously measurement value or more than the specified value, or if the dielectric loss factor greater than the specified value, it shall be dried.
Precautionary test: Perform precautionary tests such as measuring insulation resistance, dielectric loss factor and chromatographic analysis of dissolved gases in oil for winding and terminal sieves. The test results of these items should be thoroughly analysed for defects such as water ingress, dampness or poor manufacturing processes. Partial discharge measurement can also be performed to sensitively detect partial discharge defects.

Temperature monitoring: Monitor the environmental conditions around the current transformer to ensure that the temperature is within the specified working range. Ensure that the working temperature of the current transformer is below 50°C. If working in a hot environment, take cooling measures such as installing heat sinks or ventilation devices. In some enclosed electrical control cabinets, small fans are installed to ventilate and cool current transformers.
Humidity control: For DP current transformers operating in humid environments, dampproof measures should be taken, such as the use of well-sealed housing and the placement of a desiccant inside the housing.
Corrosion treatment: In environments where chemical corrosion is a risk, corrosion resistant casing materials is used or transformers are embalmed.

Secondary circuit operation: When the secondary circuit is maintained or repaired, the operation procedure shall be strictly followed to ensure that the secondary circuit is always closed. For example, the secondary circuit is short-circuited before the secondary connection is removed, and then the short circuit line is removed after the operation is complete. Install protection devices in secondary loop to prevent opening. If an open signal is detected in a secondary loop, it should be judged and processed as soon as possible. If power shutoffs are not permitted, the main load current should be minimized to ensure a safe distance between the body and the charged parts, and insulation tools should be used to short-circuit circuit at the opening point, then troubleshoot and finally short-circuit. In the operation process, must have the person to supervise, pays attention to personal safety.
Records and reporting: Maintenance records shall record in detail the results of each inspection and maintenance. Regularly report to management on the maintenance of the current transformer for timely action. Personnel training of personnel: Train operators and maintenance personnel regularly to improve their knowledge of transformer maintenance and to raise employees' awareness of the importance of transformer accuracy.