Inspection of Connection of Current Transformers

1. To identify common faults such as disconnection or short circuits in the secondary winding of the current transformer, wires connected to the A-phase and C-phase voltage terminals of the energy meter can be disconnected in sequence. The disc of the energy meter should rotate during this process.

If the disc does not rotate after disconnecting the A-phase voltage, it indicates that the C-phase of the current transformer has a disconnection or a short circuit. If the disc does not rotate after disconnecting the C-phase voltage, it indicates that the A-phase of the current transformer has a disconnection or a short circuit. Suppose the cosg value is close to 0.5 (rational) at the moment. In order to prevent misinterpretation, the C-phase voltage can be used instead of the A-phase voltage connected to the energy meter. If the energy meter shows an obvious flip, it means that there is no disconnection or short circuit in the A-phase current.

2. To distinguish whether the voltage transformer is reverse-connected or not, the current meter can be connected to the secondary winding of the current transformer to measure the current. For the Y-star connection, when the voltage transformer is all-phase and polarized in reverse, the line current of the central phase will be 2 times that of the other phases.

If all the polarities of the current transformer are reversed, a vector diagram for the energy meter coordination wiring should be made, and comprehensive analysis should be conducted.

3. To verify whether the current transformer is installed with ground connection or not, a single current meter can be used for accurate measurement. When measuring accurately, one end of the current meter is connected to the terminal of the voltage transformer that is not installed with ground connection, and the other end touches the secondary winding of the current transformer. If the current meter reads 100V, it indicates that the current transformer is installed with ground connection. If the current meter reads 0, it indicates that the current transformer is not installed with ground connection.

4. To verify the appropriateness of the ground connection of the current transformer, a current meter can be used for accurate measurement. Therefore, one end of the current meter should be grounded.

Wires connected to other terminals should touch the current terminals of the energy meter respectively. If the terminal is installed with ground connection, the current meter should not display any reading, and the disc speed of the energy meter should not be affected. If the terminal is not installed with ground connection, the current meter will display a reading, and the disc speed of the energy meter will be affected.

Acrel Co., Ltd. is a high-tech enterprise that integrates the research and development, production, sales, and services of energy efficiency management and electrical safety systems. As a manufacturer of "Acrel" intelligent energy meters equipped with a complete production line from cloud platform software to sensors, we welcome your inquiries.

Related Articles about Acrel

Wirelessly Wise: Navigating the Benefits of IoT Energy Metering Installation and Setup of DC Power Monitoring Systems Testing and Commissioning Procedures for Medium Voltage Motor Protection Relays Unleashing the Power of Digital Multi-Function Meters