On Jun 18, 2014, at 4:23 PM, Todd Goodman <tsg at bonedaddy.net> wrote: A lot of those machines run on plain office wall power, i.e., 15 amp 115 volt outlets in the USA, or < 10 amps in 220 volt countries. Sizing AC is easy. All the electric power you feed to your computer turns to heat. (Well, a trifling fraction might go elsewhere, like the transmit power to your ISP.) So whatever your AC capacity is, you need to be able to get rid of that quantity of heat. In metric this is easy; in funny units you?ll have to find the conversion from watt to BTU or whatever. paul

Hi Todd, Do you need three-phase? Depending on where you are, you may have a hard time talking your PoCo into running three-phase to a private residence. If you have a lot of three-phase gear, might be better to rent some old industrial space or something ;) You also have the option of phase converters and MG sets like the home machine shop folks but those can get pricey. Will the new building have its own drop, or will it be fed from your home?? A lot of guys will tell you if you are building a shop from scratch, just go and put 200A service in and be done with it. The price difference is not big to put in 100A service versus 200A service from scratch... basically just the price difference on the breaker box. It will cost you a lot more to rip out and replace once you have whatever gauge wiring run everywhere, the wallboard is up, it's painted, etc. Consider, how much of this stuff you will actually run concurrently for any length of time... Electric rates are only going to increase as time goes on. This old stuff, it's just chock full of low-efficiency linear power supplies and tons of 5V TTL so it sucks a lot of electricity even when idle. So, for purposes of determining power consumption and how much cooling you will require, I'd just run with the maximum figure printed on the boilerplate. Basically consider every watt that goes in will be dissipated as heat. 1 watt = 3.41 BTU/h. Best, Sean On Wed, Jun 18, 2014 at 4:23 PM, Todd Goodman <tsg at bonedaddy.net> wrote: > Hi, > > I've just built a new building that will be part machine shop and part > vintage > computer display area (and workshop for repair, etc.) > > I'm trying to size power requirements and AC requirements. > > I know that without specifics as to exactly what I'll be running (and > all the options) then it's really hard to come up with anything. > > At the same time I need to decide and get the building wired up and the > cooling set up. > > I have a number of different racks of PDP-8 and PDP-11 equipment along > with other more personal sized computers. > > Obviously not all will be powered up at once, but I'd like to spec out > requirements so that I can at least run a few at a time. > > Likewise with the AC. I'd like enough AC to be able to run for as long > as I want without overheating the equipment or myself (and I overheat > easily.) > > I know some people have been setting up shops recently and I guess I'm > wondering what they've been doing for both electrical and AC. > > Any input is greatly appreciated. > > Thanks, > > Todd >

On Jun 18, 2014, at 4:44 PM, Sean Caron <scaron at umich.edu <javascript:;>> wrote: If Rotary converters are effective but pricy. Solid state variable frequency motor controllers (basic ones) are a lot more economical. They will do for a few kW of 3-phase power. They will also serve if you need a different frequency ? not usually a consideration but it matters if you have an old Cyber, or possibly some military surplus gear. paul

Rotary converters are effective but pricy. Solid state variable frequency motor controllers (basic ones) are a lot more economical. They will do for a few kW of 3-phase power. They will also serve if you need a different frequency ? not usually a consideration but it matters if you have an old Cyber, or possibly some military surplus gear.

Those are rotary converters, and when built correctly they have excellent phase balance. Some of the articles discuss in detail how to achieve that. Basicallly, those are rotary transformers, very similar to the old ?dynamotor? power supplies found in WW2 era military radio gear. Think of it as a motor and generator, merged together.

You can buy them commercially at machinery supply companies, but the DIY kind you describe are essentially the same thing and can be much cheaper if you can find the motor component cheaply.

Not except by an expert, which are probably nonexistent these days.

Yes, but the motor in a rotary converter is a 3 phase motor, not a single phase motor. That?s the whole idea: connect the input to one of the windings, and a run capacitor to the remaining terminal, then draw 3 phase power from all three terminals.

Those are rotary converters, and when built correctly they have excellent phase balance. Some of the articles discuss in detail how to achieve that. Basicallly, those are rotary transformers, very similar to the old ?dynamotor? power supplies found in WW2 era military radio gear. Think of it as a motor and generator, merged together.

On 06/18/2014 02:35 PM, Guy Sotomayor wrote: Probably a US-EU difference, but standard residential distribution in the US tends to be 200A 240V. Some of my neighbors have 400A service to their homes.