Here are the minutes of our last 1401 restoration meeting, April 2nd, including a table of the 50-Hz conversion options as Grant presented them...
IBM 1401 Restoration Project
Meeting #4, April 02, 2004
Summary by R. Garner
Mike Cheponis, Mike Falarksi, Robert Garner, Dag Spicer Eric Smith Grant Saviers Dick Weaver
50-Hz conversion options Appraise the newly arrived 1401 system!
The 1401 shipment arrived at the CHM?s loading dock on Thursday, March 18th. Mike Zahares and crew skillfully unpacked it the next day and arranged the units according to our floorplan. It looks fantastic! Although some of the units (1402, 729) have some dirt, grime and rust, it all appears to be good shape for its age, especially the CPU unit.
Mike F followed up with Liebert maintenance and they repaired the 20-ton ?System 3? air-conditioning unit, so that it no longer produces an obnoxious rattling noise.
The entire meeting was spent discussing our 50-Hz conversion options. The major conversion options are:
· Grant presented information on the tradeoffs on the motor generator and solid-state converter options. In addition to the raw specs, other items to consider include the need for a sound enclosure, location and cooling of the unit, and motor load startup demand. Some of the motor generator sets would be quite loud and probably should not be located in the server room with the 1401, even with a sound enclosure, which may also effect the cooling of the unit. If in another room, then cooling of that room and getting power to it becomes a construction/building code issue too. Delivery, availability, maintainability, used vs. new, and difficulty in operating are additional considerations.
- Purchase and install a 50-Hz motor generator set.
- Purchase and install a 50-Hz solid-state static power converter.
- Modify the 1401 to operate at 60 Hz. Looking at the machine?s documentation, it looks like it had been converted from 60 to 50 Hz in Europe. Challenges include several ferro-resonant power supplies in the 1402, and some AC motors in the 1402, 1403, and 729 (although labeled 50-Hz, not sure if they are synchronous). One option would be to swap components, such as power supplies, with the 1401 the museum already has (if the museum approved).
- Determine whether the UPS (MGE EPS-2000 Data Power System) can be converted to 50-Hz operation. Would also need to confirm that the building?s other items powered by the UPS feed (i.e., servers and emergency lights) properly operate at 50-Hz power.
These are the primary options discussed in the meeting (MG = Motor Generator):
1. Solid-state, static converter 2. MG: 60-Hz-induction motor to 50-Hz synchronous generator, V-belt 3. MG: 60-Hz-sync motor to 50-Hz sync generator, cog timing chain 4. MG: 60-Hz-induction motor to 50-Hz sync gen, direct-coupled 5. MG: 60-Hz-sync motor to 50-Hz sync generator, direct-coupled
The discussion resulted in this table of approximate-to-estimated features, specs, characteristics, and estimated costs. For costing, heat generation, etc, we?re assuming the max anticipated power load of 12.5 - 12.9 kVA (all five 729?s and 1401, 2, 3, 6 running).
Feature 1) Static 2) MG-Ind/Belt 3) MG-Syn/Cog 4) MG-Ind/DC 5) MG-Syn/DC Cost/kW $ 1000 $ 660 $ 640 $ 300 ? Cost (New) $ 12.5 k $ 8.2 k $ 8.0 k $ 3.9 k ? Size 4 ft3 2?x3?x4? 2?x3?x4? 2?x3?x4? 2?x3?x4? Noise @ 3 ft 60 dBA 80 dBA 85-90 dBA 70 dBA 70 dBA Efficiency 88 % 75 % 75 % 75 % 75 % Heat generated 2.9 kW 3.3 kW 3.3 kW 3.3 kW 3.3 kW Freq Accuracy .001 Hz ±2 % .01 Hz (PG&E) 2.5 % .01 Hz (PG&E) EMI/RFI ? Low Low Low Low Install Cost Smallest Large Largest Medium Medium Service Cost No Yes Yes Yes Yes Although option #1, the static converter is most appealing from an ease of use, noise, accuracy, reliability, install ability, and maintainability perspective, it is most expensive. The other interesting option in this table is #4, the direct-coupled, induction motor generator set. However, these MG sets come from an outfit in Brazil, with a long lead-time of 14 weeks. It would be good to review the actual specs (what makes them cheaper?) and look for a quote from a second source. Also, what about used static inverters and MG sets?
Grant ? Look for a 2nd quote on a direct-coupled MG set. Explore other options and prices for used units.
Other open A/I?s:
Robert ? Bring-up & restoration plan. Kirsten ? Accessioning and availability of museum?s current 1401 docs. Accessioning of the new 1401 docs.