PSCAD is a fast, accurate, and easy-to-use power system simulation software for the design and verification of all types of power systems. PSCAD is most suitable for simulating time domain instantaneous responses, also known as electromagnetic transients or instantaneous solutions, in both electrical and control systems.

Phase to ground fault, phase-to-phase fault and increasing load were simulated using PSCAD.
This simulation is important to show the current characteristics when fault occured.

Parameter of sources, transformer and transmission line from the field research entered into the flexible graphical user interface of PSCAD. Low voltage power system represented by selecting a source of 11KV connected to a step down transformer 11kV/0.415kV. Breaker was connected after the transformer secondary terminal while load at the end of the circuit.

 
Phase to ground fault current waveform

 
Phase to phase fault current waveform

 
Increasing load current waveform

Phase to ground and phase to phase fault shows that the current of a faulty line can rise up to 2kA. This high surge current can damage the substation transformer and causes outage to supplied consumer. Fuses between the transformer and the consumer will normally blew if this fault occured.

Increasing load which cause by high power usage from the consumer is less dangerous since it occured with steady increase of current flow. Fuse will eventually blew when it reaches it's current rating and protect the transformer from excessive current flow.

The simulation result shows that overcurrent occured at each fault thus a devices which sensors the current flow will be used for developing the ACB.