ElectricalDesign release 16.6.0
14.7.2016
The main task an Electrical designer must perform is make sure that IEC standards and National regulations (e.g. BS 7671) are satisfied.
Circuit (feeder) protection checks are of primary consideration. In 16.6 release the feature for circuit protection checks was redesigned in order for these checks to be made much more easily.
Overview of all circuits protection checks
The columns of circuits grid marked as Overload protection allow you to view all properties that take part in the protection against overload at a glance. More specifically, these columns are Load Ib, PD In and Cable I.
The columns of circuits grid marked as Short-circuit protection allow you to view all properties that take part in the protection against short-circuit at a glance. These coluns are PD I²t, Cable k²S².
For each circuit we see the detailed circuit calculations in the form Circuit protection checks.
Protection against overload
The Standard IEC 60364-4-43 Electrical installation of buildings - Protection against overcurrent specifies coordination between conductors and overload protective devices (normally placed at the beginning of the conductor to be protected).
Click on tab Overload protection to see:- Load properties e.g. Ib
- Protective device properties e.g. In
- Cable properties e.g. Iz
- A green light ON if the condition Ib < In < Iz is satisfied
- Time-Current Curve (TCC) of the protective device
Protection against short-circuit at beginning of conductor
A cable is protected against short-circuit if the specific let-through energy of the protective device (I²t) is lower or equal to the withstand energy of the cable (k²S²)
Click on tab Short-circuit protection to see:- Withstand energy of cable e.g. k²S²
- Protective device's let-through energy e.g. I²t
- A green light ON if the condition I²t < k²S² is satisfied
- Let-through energy Curve of the protective device
Protection against short-circuit at end of conductor
Regulation requires that the circuit breaker trips instantaneously at the minimum short-circuit current: the threshold of the short-circuit protection (taking into consideration also the tolerances) shall therefore be lower than the minimum short-circuit current at the end of the conductor.
Click on tab Ik,min to see:- Short-circuit current analytical calculation at the end of conductor e.g. Ik,min
- Protective device e.g. MCB instantaneous setting I3
- A green light ON if the condition Ik,min > 1.2*I3 is satisfied
- Time-Current Curve (TCC) of the protective device
Earth fault loop impedance and Protective Earthing (PE) conductor check
IEC standards or National Regulations require that in case of earth fault the circuit breaker disconnects automatically within the time given by regulations e.g. 0,4s for final circuit.
Click on tab PE conductor to see:- Analytical calculation of earth fault loop impedance (ELI) e.g. Zs
- Analytical calculation of earth fault loop current e.g. Ia
- Maximum permitted disconnection time e.g. ta,max
- Protective device disconnection time e.g. ta
- Analytical calculation of minimum PE conductor cross-section e.g. SPE,min
- First green light ON if the condition ta < ta,max is satisfied
- Second green light ON if the condition SPE > SPE,min is satisfied
Discrimination
Discrimination is achieved by automatic protective devices if at fault condition, occurring at any point in the installation, is cleared by the protective device located immediately upstream of the fault. All other upstream protective devices must remain unaffected.
Click on tab Discrimination to see:- a list with active and all upstream protective devices
- the active protective device is in the bottom of the list
- Each protecive device is plotted by its time/current curve using with different color
MCCB equipped with thermomagnetic trip unit
If the selected protective device of the active circuit is a MCCB, the MCCB Settings tab is included in the form.
If the selected MCCB is equipped with thermomagnetic trip you can adjust:
MCCB equipped with electronic trip unit and functions LSI
If the selected MCCB is equipped with electronic trip you can adjust:- Function L (Long time delay) setup current and time delay
- Function S (Short time delay) setup current and time delay
- Function I (Instantaneous) setup current without delay
MCCB equipped with electronic trip unit and functions LI
If the selected MCCB is equipped with electronic trip you can adjust:- Function L (Long time delay) setup current and time delay
- Function I (Instantaneous) setup current without delay
