Processor mounting

Mark Buskell · Apr 1, 2007

Is there any danger with mounting a rack in the vertical position?
I think the current will tend to sink toward the lower end of the rack and I might need bigger fuses and thicker wire to protect them from this current drainage. I have thought of even installing a current drainage wire by connecting the positive wire to the negative wire just in case. Hoping the experts here can give me some much needed advice.

Ken Moore · Apr 1, 2007

I believe they are designed to be mounted horizontally for proper heat dissipation. Air in the bottom and out the top. So heat build up may be your biggest concern with a vertical mount.

Got me, lol.

Bob O · Apr 1, 2007

bluebyu · Apr 1, 2007

"Is there any danger with mounting a rack in the vertical position?
I think the current will tend to sink toward the lower end of the rack and I might need bigger fuses and thicker wire to protect them from this current drainage. I have thought of even installing a current drainage wire by connecting the positive wire to the negative wire just in case. Hoping the experts here can give me some much needed advice."

We often install in this way, just ensure the proper size coin is used between the hot wire and ground.

cnordhof · Apr 1, 2007

Its not so much the current drainage thats the problem, Its the speed that it goes past the outputs. Always mount the power supply lower then it can push the power up-- keeping the wires full.

Bob O · Apr 1, 2007

No, you want to use the gravity feed power supplies mounted high up in the cabinet. Let gravity fill the wire with power so you have extra left over for the next expansion project.

In addition, with the power supply mounted high, the temperature rise in the cabinet will increase the pressure in the power supply cause the power to get packed in the wires better.

It’s a win win situation all around.

Mickey · Apr 1, 2007

This should help solve your problem:

Dissipation in the quantum Hall effect by transverse circulation of electrons

E B Hansen
Oersted Laboratory, Niels Bohr Institute, Universitesparken 5, DK-2100 Copenhagen, Denmark

Abstract. In a mid-plateau situation there exists a reversible uphill flow (in the direction of the Hall field Ey) of the electron liquid with the current density Jliq.. Inelastic processes cause excitations to be scattered downhill with the current density Jexc., which satisfies the condition Jexc. + Jliq. = 0. The conversion at the edge of the reversible uphill flow to the dissipative downhill flow is mediated by the edge states. It is shown that transverse circulation of electrons implies the temperature independence of the ratio Δρxy/ρxxmin, where ρxxmin is the minimal value of the longitudinal resistivity at the given temperature T, and Δρxy = ρxy(T) - ρxy(0).

Tom Jenkins · Apr 1, 2007

If you use gravity drainage to accellerate ground currents you need to make sure that you have an adequate radius on wire bends or you will get electron spin-out on the sharp turns.

rdrast · Apr 1, 2007

Oh Wow!
That would explain the 'Lost Bits' from another thread, wouldn't it? Good thinking Tom!

Tom Jenkins said:
If you use gravity drainage to accellerate ground currents you need to make sure that you have an adequate radius on wire bends or you will get electron spin-out on the sharp turns.

rsdoran · Apr 1, 2007

rdrast said:
Oh Wow!
That would explain the 'Lost Bits' from another thread, wouldn't it? Good thinking Tom!

What is funny, maybe ironic is the word, is that on this site you never know when a question like that is serious.

bulletin blues · Apr 1, 2007

I've used current sourcing cards to eliminate that current sinking problem in the past.
Hope that helps.

geniusintraining · Apr 1, 2007

[off topic]

A man came home from work one day to find his wife on the front porch with her bags packed.

'Just where the heck do you think you're going!', said the man.

'I'm going to Las Vegas', said the wife, 'I just found out I can get $400 a night for what I give you for free!

'The man said, 'Wait a minute!', and then ran inside the house only to come back a few minutes later with his suitcases in hand.

'Where the heck are you going?', said the wife.

The man said, 'I want to see how you're gonna live on $800 a year!'

[Back OT]

Mark,

I think you can only do this with a SLC 503

Good luck

danw · Apr 1, 2007

Remember all that physics drivel about right hand rules for magnetic fluxes and what not? Well, that's what you run into when rotating the rack.

Mounting the back plane horizontal invokes the fomger-thumb rule with its attendant induction problem, like Tom Jenkins alluded to with the electron spin out phenomenon. The Swedes pioneered the Bergman solution for this phenomenon. The measurement is in ****, (Swedish for speed). Like the farad, a **** is huge quantity, so most Svensons come in microFart ranges (uFt). In order to keep spin out within reasonable levels, the rule of thumb is to allow 2 or 3 uFt Svenson on each slot.

Plus the horizontal back plane has formed a capacitor with the earth as the other plate. At backplane frequencies, capacitive leakage EXCEEDS the gravity drainage requiring doubling of power supply capacities.

Dan

tomalbright · Apr 1, 2007

This is the only way I have found to make Blue Hose outperform Ethernet. Mount the CPU at the top of the cabinet, and the rest of the comm modules at the bottom, all vertical.

I'm surprised it hasn't become a standard.

Steve Bailey · Apr 1, 2007

One key point that everyone has overlooked so far is that if you're going to mount the rack vertically, you need to specify I/O modules with ratchet mounts and be sure to install the ratchet mount properly. Without the ratchet mount, when power fails, all the inputs and outputs fall to the bottom and there is no guarantee that they'll make it back to the proper module once power is restored. If an input should wind up at a location where the PLC expects an output, the result can be similar to when a particle of matter meets its anitmatter counterpart, leaving a big hole where the smoke can get out.

For additional safety, install an open collector module at the bottom location. This provides a safe landing place for any inputs or outputs foolish enough to be out and about without a safety harness.

Processor mounting

Mark Buskell

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Ken Moore

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Bob O

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bluebyu

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cnordhof

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Bob O

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Mickey

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Tom Jenkins

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rdrast

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rsdoran

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bulletin blues

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geniusintraining

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danw

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tomalbright

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Steve Bailey

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