4 ms·

There's another UPS-source option, which is also my favorite, flywheel! Back in the 00s I visited a DC that two very large flywheel UPS that were being trialed

There's another UPS-source option, which is also my favorite, flywheel! Back in the 00s I visited a DC that two very large flywheel UPS that were being trialed to replace the battery room.

pas 8y ago
Flywheels are alive and well in the DC industry. They are used for those crucial seconds while the generator starts up. And as a backup for the UPS-es. (After all, those batteries might not be in top shape all the time.) Though I imagine eventually battery tech will take over.
- TheSpiceIsLife 8y ago
  If the flywheel can be integrated in to the generator design then generator startup can be almost instantaneous. Synchronisation would still take a few moments. I don’t know if anyone is building systems like that though?
  - Animats 8y ago
    Yes, they are. Hitek builds those. The 2007 outage of 365 Main in SF, which took down many major web sites, was due to control problems with a set of ten of them.[1] Each unit had a motor/generator, a flywheel, and a Diesel engine on the same shaft. There's a free-wheeling clutch between the Diesel generator and the rest of the system, so the Diesel does not rotate when idle. The Diesel is started by its own starter motor, and when its RPM reaches that of the generator, the clutch engages and it starts powering the generator. PG&E had a transformer fire which caused large voltage swings. The flywheels kept the generators turning, and the ten Diesel engines started OK. Then outside power came back up, and after a time delay, the Diesels shut down. Then outside power failed again, and because of a timing incompatibility between the power control and engine control, some of the engines would not restart that soon. There was a minimum "off" time on the engine; it had to stop before it could be restarted. The engines that did start were not enough to handle the load; they overloaded and their controllers shut them down, shutting down the whole data center. [1] https://www.datacenterknowledge.com/archives/2007/07/24/generator-failures-caused-365-main-outage https://www.datacenterknowledge.com/archives/2007/07/24/gene...
    - TheSpiceIsLife 8y ago
      Thanks for the info. I used to work in a data centre in Adelaide doing physical infrastructure and security, so this is right up my alley.

There's another UPS-source option, which is also my favorite, flywheel! Back in the 00s I visited a DC that two very large flywheel UPS that were being trialed to replace the battery room.

pas 8y ago

Flywheels are alive and well in the DC industry. They are used for those crucial seconds while the generator starts up. And as a backup for the UPS-es. (After all, those batteries might not be in top shape all the time.) Though I imagine eventually battery tech will take over.

TheSpiceIsLife 8y ago
If the flywheel can be integrated in to the generator design then generator startup can be almost instantaneous. Synchronisation would still take a few moments. I don’t know if anyone is building systems like that though?
- Animats 8y ago
  Yes, they are. Hitek builds those. The 2007 outage of 365 Main in SF, which took down many major web sites, was due to control problems with a set of ten of them.[1] Each unit had a motor/generator, a flywheel, and a Diesel engine on the same shaft. There's a free-wheeling clutch between the Diesel generator and the rest of the system, so the Diesel does not rotate when idle. The Diesel is started by its own starter motor, and when its RPM reaches that of the generator, the clutch engages and it starts powering the generator. PG&E had a transformer fire which caused large voltage swings. The flywheels kept the generators turning, and the ten Diesel engines started OK. Then outside power came back up, and after a time delay, the Diesels shut down. Then outside power failed again, and because of a timing incompatibility between the power control and engine control, some of the engines would not restart that soon. There was a minimum "off" time on the engine; it had to stop before it could be restarted. The engines that did start were not enough to handle the load; they overloaded and their controllers shut them down, shutting down the whole data center. [1] https://www.datacenterknowledge.com/archives/2007/07/24/generator-failures-caused-365-main-outage https://www.datacenterknowledge.com/archives/2007/07/24/gene...
  - TheSpiceIsLife 8y ago
    Thanks for the info. I used to work in a data centre in Adelaide doing physical infrastructure and security, so this is right up my alley.