The CBCT also known as a zero sequence CT is used for earth leakage and earth fault protection. In the CBCT, the three-core cable of three single cores of three phase systems passes through the inner diameter of the CT. When the system is fault free, no current flows in the secondary of the CBCT. When there is an earth fault, the residual current (zero phase sequence current) of the system flows through the secondary of the CBCT and this operates the relay. In order to design the CBCT, the inner diameter of the CT, the relay type, the relay setting and the primary operating current needs to be stated.

Core balance current transformers are intended for providing a very sensitive method of earth leakage protection on three-phase electrical systems with suitable relays.

Cables of all phases pass through the inner diameter of the transformer and there is no output under no-fault conditions. In the event of an earth-fault a non-zero current exist and induces a changing magnetic field within the core, which in turn generates a secondary voltage which operates a relay (via burden).

Customizable Parameters:

• Primary rated current
• Relay type
• Relay setting
• Burden
• Maximum System Voltage
• Frequency
• Inner diameter of the CT