Electrician's Handbook

Every professional needs a guide to carry with him and to guide him constantly.

As Voltimum Turkey team, we have prepared the article that we have prepared as a handbook for electricians to shed light and guide you.

Residual current protection with toroid current transformer Although there are various protection methods against leakage current, one of the most common methods is protection with toroid current transformer. First of all, if we recall the concept of leakage current; In normal operating conditions, the vectorial sum of the currents passing through the phase and neutral is zero. In abnormal situations, that is, when an insulation fault occurs, a difference occurs in the return of the current from the phase through the neutral conductor. This difference is detected by the residual current device and opens the circuit. This system consists of four parts in terms of structure. First of all, if we recall the concept of leakage current; In normal operating conditions, the vectorial sum of the currents passing through the phase and neutral is zero. In abnormal situations, that is, when an insulation fault occurs, a difference occurs in the return of the current from the phase through the neutral conductor. This difference is detected by the residual current device and opens the circuit.

There are some critical points to be considered in protection against leakage current with toroid current transformer. The first of these is the necessity of passing 3 phase and neutral conductors through the toroid relay. In some applications, since the installer does not know the product, it has been observed that the neutral conductor is passed outside the toroidal current transformer, not inside. Such a fault will be detected as leakage current by the residual current detection relay and will send a trip signal to the circuit breaker and will open the circuit breaker. In other words, it will make zero. Another important point is to make the right connections. As mentioned above, the four parts used have special connections among themselves. Incorrect connection will affect the entire system and cause it to fail. In addition, the connections made with the undervoltage coil or the opening coil, which will be taken according to the user's preference, should also be made in accordance with the rules.