High PFC

[nozspark]

Just done a test at a house, got a reading for the PFC (L-N)@ 7KA, what do you think??
Oh yeh, it's not next door to a substation either..

 

[Spark123]

Is the cutout fuse rated 7KA+?

 

[Lectrician]

the lecky boards 33kA bs1361 will cover it

 

[RF Lighting]

7kA is a little higher than normal, but not all that unusual for a domestic supply, and certainly not unusual for commercial / industrial supplies.

 

[Spark123]

Yup, our supplies at work are all protected by HBC fuses due to the close proximity to sub-stations.

 

[RF Lighting]

Best I've had was in a warehouse we rewired last winter. Almost 15kA at the incommer. The substation was IN the switchroom

 

[Spark123]

I have never needed to PFC test our supply, I would think 15kA would be a bit low - the spare fuses are a similar size to a packet of pringles.

 

[RF Lighting]

have you never tested the Ze either?

 

[Spark123]

Nope, it is a rareity nowadays for us to do any installation work whatsoever, we do not have dno cutouts like normal premises as the eleccy comes in at 3.3kv. Most of my work nowadays is maintenance work related to elv and process instrumentation. I do a lot more with programmable controllers sequences etc as opposed to the good old hands on heavy stuff.

 

[kai]

No cut-out?

Then what protects your installation? - the "cut-out" houses the critical main fuse for the whole installation, often its safe breaking capacity is 80kA in industrial applications.

 

[RF Lighting]

I have worked on one factory which had no cut out.

The LV output of the transformer fed straight into the 1000A main breaker in the panel board.

Scary stuff.

 

[Jaymack]

I have worked on one factory which had no cut out.

The LV output of the transformer fed straight into the 1000A main breaker in the panel board.

Scary stuff.

Not so scary, it is usual to have at least O/C and E/F protection on the HV side of the transformer, using fast acting electronic relays. This is a common way of supplying industrial LV boards.

Jaymack