On 10/12/24 22:26, ben via cctalk wrote:
On 2024-10-12 7:40 p.m., Jon Elson via cctalk wrote:
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
What did they use for air conditioning?
All 360's except the model /85 were air-cooled. The model
/85 was water cooled, and was essentially a prototype of the
370/165.
I can't answer for all installations, but our old computer
center had a huge AC unit in the basement that blew cooled
air under the raised floor.
Jon
