13 Oct
2024
13 Oct
'24
8:29 a.m.
Water cooled
Am 13.10.2024 um 11:15 schrieb ben via cctalk
<cctalk(a)classiccmp.org>rg>:
On 2024-10-12 7:40 p.m., Jon Elson via cctalk wrote:
What did they use for air conditioning?
On
10/12/24 20:07, Jon Elson via cctalk wrote:
On 10/12/24 16:25, Wayne S via cctalk wrote:
> Didn’t all the IBM mainframes use 400hz? Maybe ask the IBMers how they got 400hz.
> Also, can the local power company supply it?
>
Oh, the IBM 7090 series had a 400 Hz motor generator. The mid-range IBM
360's (360/50 and 360/65) has "converter-inverters". There was a star
rectifier that took in 208 V 3-phase and converted it to DC with an inductor-input filter
at about 300 V DC. This was then fed to an inductor-input resonant inverter with fast
SCRs at 2.5 KHz. All the power supplies for logic, memory, etc. ran off 120 V
single-phase 2.5 KHz power. This kept the transformers and filter caps and inductors very
small. The inverter SCRs were commutated by two smaller SCRs that momentarily shorted the
main SCRs through oil-paper caps.
The problem with this system is it didn't offer much ride-through capability if you
had crummy power quality.
Jon