Fault Current Calculation with CLIP
Fault Current Calculation with CLIP
(OP)
When calculating the three phase fault currents in a power network, should a protection device be considered in limiting the current? Let me explain a little more.
At the power station, there are 12 generators that are connected on two separate buses (6 on each) that are inter-tied by a CLIP (current limiting protector). This CLIP works as a fuse and will operate at, lets say, 3kA. This will reduce the fault current at the power station and throughout the network. The clip can also be disconnected in order to operate as two independent buses. There are 2 feeders connected on each side of the bus and do not connect with each other downstream.
So when performing the maximum 3 phase fault calculations, should I be using the fault contribution for only the generators on the same side as the feeder? I am concerned because a busbar downstream is rated at 30kA for 1s and is providing a fault level higher than this when using the 12 generators. I have never previously considered protection devices eg. fuses/CLIP in fault calculations as the calculation is performed first, then the protection devices are chosen to limit this.
Are there any reference to standards that you can think of that might make this clear? My calculations are for Australia, but I have been using IEC 60909 as this is the calculation method in software package PowerFactory.
At the power station, there are 12 generators that are connected on two separate buses (6 on each) that are inter-tied by a CLIP (current limiting protector). This CLIP works as a fuse and will operate at, lets say, 3kA. This will reduce the fault current at the power station and throughout the network. The clip can also be disconnected in order to operate as two independent buses. There are 2 feeders connected on each side of the bus and do not connect with each other downstream.
So when performing the maximum 3 phase fault calculations, should I be using the fault contribution for only the generators on the same side as the feeder? I am concerned because a busbar downstream is rated at 30kA for 1s and is providing a fault level higher than this when using the 12 generators. I have never previously considered protection devices eg. fuses/CLIP in fault calculations as the calculation is performed first, then the protection devices are chosen to limit this.
Are there any reference to standards that you can think of that might make this clear? My calculations are for Australia, but I have been using IEC 60909 as this is the calculation method in software package PowerFactory.






RE: Fault Current Calculation with CLIP
RE: Fault Current Calculation with CLIP
I've found the following in IEC 60909-0 section 2.4 Maximum short-circuit currents;
"When calculating maximum short-circuit currents, it is necessary to introduce the following conditions:
- choose the system configuration and the maximum contribution from power plants and network feeders which leads to the maximum value of short-circuit currents at the short-circuit location, or for accepted sectioning of the network to control the short-circuit current"
Does your interpretation of that include using a CLiP to separate the buses to control the short-circuit current?
RE: Fault Current Calculation with CLIP
RE: Fault Current Calculation with CLIP
RE: Fault Current Calculation with CLIP
RE: Fault Current Calculation with CLIP
The Clip uses an explosive device triggered by a fast overcurrent or rate of rise sensor. It monitors the current and triggers the explosive charges to blow the bus bar apart when the di/dt and the current magnitude indicate a high level fault is occurring. The Clip is not affected by downstream arcing impedance and can clear before most devices can respond so there is little interaction between it and other components.