Effect of Short Circuit Current on Electric Panel or Switchgear

Conductor size must take in to account electro-mechanical and thermal stresses imposed by a short circuit.

You can reduce the electro-mechanical stress by increasing the number of supports but then this increases the thermal stress.

It's time for a juggling act.

A short-circuit results in an excessive current due to low impedance of the faulty circuit between the source of supply and the fault. This excessive current causes excessive heat (= IC', . R) in the current-carrying conductors and generates electromagnetic effects (electric field) and electrodynamic forces of attraction and repulsion between the conductors and their mounting structure. These forces are distributed uniformly over the length of conductors and cause shearing forces due to the cantilever effect as well as compressive and tensile stresses on the mounting structure. The effect of a short-circuit therefore requires these two very vital factors (thermal effects and electrodynamic forces) to be taken into account while designing the size of the current-carrying conductors and their mounting structure. The latter will include mechanical supports, type of insulators and type of hardware, besides the longitudinal distance between the supports and the gap between phase-to-phase conductors.

Why don't you attend to our training programme on Electrical Design of Switchgear Assembly?

Since you have asked for effect of short circuit,

During short circuit in the switch board, there will be

1)Electro - dynamic forces acting on the busbars

2) Temperature of busbars,current carrying elements will get increased.

If the Switch board is designed to withstand a particular short circuit current for a particular time, the switch board will withstand and there will not be any failure.

If the short circuit current and time of fault are greater than the designed values the switch board will fail ( Blast into pieces)

Who appointed you as a Power electric engineer?

Good question?

Just hope I'm not around to find the answer