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Part2: Minimum clearance of live parts

Part2: Minimum clearance of live parts

Part2: Minimum clearance of live parts

(OP)
Hi Again,

Let me take the "Minimum clearance of live parts" post a little further.

I have the following splitter trough in my plant.  It was made by a local switchgear manufacturer.  The specs are given below:

Phases: 3
voltage: 600v
Current: 800A
Bus: Copper, non-insulated 1/2" x 1 1/2"
Phase to Phase spacing: 3"
Phase to ground Spacing: 1"
RMS sym Rating: 25KA
Insulator spacing: 7" (4 Insulators/phase, 33" bus,i.e. 6" overhang on ends)

This splitter was never tested. However, the manufacturer says that based on it's calculations, the KA rating is good (it's always good until a fault occurs...).  

Does anyone think the above Fualt rating seems reasonable... maybe a formula...

Thanks again

Tulum    

RE: Part2: Minimum clearance of live parts

T=(0.0857*A/I)^2

A is copper cross sectional area in circular mils. T is time in seconds.

25kA gives a 10s clearing time. Maybe the switch contacts are the limiting factor?

RE: Part2: Minimum clearance of live parts

The bracing may be the limiting factor instead of the thermal rating.  You could try to apply the equations in IEEE Std 605, IEEE Guide for Design of Substation Rigid-Bus Structures.

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