Determination of Phase to Phase Short-Circuit Current, and Phase to Ground Short-Circuit Current

Phase to phase Short-circuit current and Phase to ground Short-circuit current is the current occurs in the conductor when there is a short-circuit electrical fault between phases with each other and between phase and ground. Measuring these short-circuit currents helping designers choose the right types of protection for their electrical system. Ensure timely interrupt when an incident occurs.

How to measurement Short-circuit current?

The measurement of short circuit current cannot be performed as conventional current measurements. We cannot wait for a short-circuit or deliberately shorten it to measure the current. Therefore, another method is proposed, which is to calculate the short-circuit current based on measuring the impedance of the line in the system, from which the short-circuit current is calculated according to the formula of the formula OHM: U = I.R => I = U / R

Measuring short-circuit currents with a loop impedance measurement method

Note : For the electrical network in Vietnam, most of the neutral wire N and ground wire PE will not be connected together, so when measuring phase to ground Short-circuit current, the result usually is small about 25-35A. Normal Aptomat will not automatically disconnect if a ground fault occurs. Therefore, we need to use a Residual current circuit breaker for the electrical system.

Measuring short-circuit currents with PROFITEST series.

PROFITEST series of Gossen Metrawatt is a Multi-parameter testing equipment related to electrical safety. The device is able to measuring short-circuit currents with high accuracy, suitable for many types of electrical networks.

Diagram of earth current measurement with PROFITEST

In addition, PROFITEST also has function to test Residual current circuit breaker, to evaluate and test the accuracy of this type of aptomat. Other function include measuring system voltage, measuring insulation resistance between phases, ground resistance measurement for earthing systems. With the aforementioned features plus a safe and secure design. PROFITEST series of Gossen Metrawatt is  very suitable for electrical  safety inspection applications, helping engineers achieve high efficiency when performing their system inspection and maintenance.

Source: TMC


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