Panel design

[JesperMP]

Fuses are needed for flash protection, don't ever rely on a CB. Period.

With "flash protection" you mean the ability to break the short circuit level at the location, right ?
The CB you mention simply wasnt rated to the short circuit level that it experienced. Thats a fault of the designer of the electrical installation.
Fuses also have a rated short circuit level. To use fuses doesnt universally guarantee that the short circuit current can be interrupted.
In all cases every design must be checked that the short circuit level at the location doesnt exceed the rated levels of the devices intended to provide protection.

Period.

 

[Rick Densing]

Fuses on a whole have a higher interupting capacity than CB's. Especially on a cost basis.

We use exclusively the low-peak fuses from Bussmann. 300ka capacity. Usually covers most installations.

 

[Gerry M]

Hey we use the same fuses what do ya know.

The CB you mention simply wasnt rated to the short circuit level that it experienced. Thats a fault of the designer of the electrical installation.

Exactly!

Best advice is to know what you're trying to protect and make sure your choice will do the job.

That sums up the whole discussion.

 

[martyh]

back on the programming ports....

One more question about the DH+ programming ports. I remember reading in some other posts that there is a recommended length to maintain between data highway components. Do I need to maintain this length to the port? Say if I daisy chain from the panelview in the door to it?

Thanks.

 

[Voltimus]

In a panel,

Ferrules are good,
Fuses are good,
Deep wide raceways are good,
Filters?...also good,
Lights are really good,

But, dessicant(not to be eaten) and drains? it's the best, my friends!!!

Someday, I'll astonish everyone with the marvels that Hurricane Ivan has bestowed upon our functioning (thanks to dessicant and drains) floating production facility.

 

[JesperMP]

... there is a recommended length to maintain between data highway components. Do I need to maintain this length to the port? Say if I daisy chain from the panelview in the door to it?

Yes.

Now I wonder if there is a similar minimum length for RS485 networks. Does anyone know ?

 

[ianingram]

Nobody else has mentioned this...Been too busy with CB's & Fuses...






BOTTOM ENTRY



Yes, bring all cables in via the bottom of the cabinet, not the sides or top....or rear...

(At least I don't think anybody has mentioned this utoh)

 

[Eric Nelson]

BOTTOM ENTRY



Yes, bring all cables in via the bottom of the cabinet, not the sides or top....or rear...

Because?...

beerchug

-Eric

 

[Rick Densing]

[


BOTTOM ENTRY


[/B]

Most of mine sit on the floor.




You are correct in a lot of cases. Our remote boxes on machines are exposed to coolant splash and stuff, and no matter how you try, a little will always get in the box if you enter it from any side but the bottom

 

[testsubject]

Nobody else has mentioned this...Been too busy with CB's & Fuses...






BOTTOM ENTRY



Yes, bring all cables in via the bottom of the cabinet, not the sides or top....or rear...

(At least I don't think anybody has mentioned this utoh)

I agree. It helps keep the water out....

 

[JesperMP]

In the foundry business it is not uncommon to let the cables enter from the TOP - and generally keep cables high up. This because molten metal has a tendency to follow gravity and find its way into cable pits and the likes.

 

[elevmike]

The entry thing all depends on the application. In a foundry situation it dosent seem to matter. The dust always seems to find a way in....

 

[paulB]

heat load

I am looking for help from the panel builders. How do perform enclosure heat load calculations. Is anyone may recommend literature on this subject or provide some examples.
Thank you guys.
PaulB.

 

[Tom Jenkins]

Heat Loads

Most enclosure or enclosure heating/cooling equipment suppliers include formuals, nomographs, or other calculation methods in their catalogs. Look at Hoffman, Rittal, and McClean for starters.

I use a fairly simple formula originally published by Hoffman:

DeltaT = 4.08 x (Q / A) + 1.1

DeltaT is the temperatre rise inside the enclosure, °F

Q = heat generated inside the cabinet, Watts (This isn't the same as watt draw for the total cabinet - don't include motors or other devices not inside the cabinet)

A = total exposed area of the panel, square feet

 

[bernie_carlton]

Wow, Tom. This means that the inside of the cabinet will ALWAY be at least 1.1 degrees warmer than the outside even if no heat was being generated? Wow, we could hook up a heat pipe working on this perpetual difference and get free energy. What if we nested a number of cabinets inside each other? Would each inner cabinet be 1.1 degrees (at least) warmer than the next outer? Wow - we could really build up a temperature difference between the inneermost one and the outside. Now, how many can we actually nest? I knew there was something to those 'free energy' people.