#DATA BACKUP GENERATOR KICKS IN DURING MANUAL#

It’s best not to challenge UPS batteries any longer than necessary and risk the chance of a UPS failure. If it were my facility, and if it were dependent on lower cost UPS batteries (such as those supporting the vast majority of data centers), my recommendation would be to set the start time at 3 seconds. If utility power is down for more than several seconds it will probably be down for several minutes or hours, so you might as well start your engines. Most engineers, including myself, recommend programming generator start time delay settings in the 3 to 5 second range. I don’t believe there is much supporting evidence here, but it is getting quite a bit of discussion at major conferences in recent years. The other extreme, programming generator start-time delays of 15 seconds or more following loss of utility power, is driven by opinions among a minority of professionals who believe that excessive generator cold starts prematurely wear generators out.

Multiple 3 to 10 second utility power failures within a short duration can leave a UPS flywheel too depleted to provide ride-through time. For UPS backup energy storage, the recharge time is typically 10 times longer than the discharge time, so rapid short utility bumps can cumulatively draw down short-term storage (a very real concern for flywheel UPS systems). A generator start timer (typically located in the ATS or generator switchgear) will typically reset when power returns.

#DATA BACKUP GENERATOR KICKS IN DURING MANUAL#

The fourth time a re-closer opens it typically stays open for many minutes or longer (awaiting manual intervention).Īnother concern is that many times the utility fails, then returns, and almost immediately fails again. Re-closers are often programmed by the utility to open and re-close quickly a couple times, resulting in power bumps of 1 second or less, then to remain open up to about 3 seconds on the third and typically final attempt. The short power bumps typically result from utility re-closers that automatically open and close quickly in an attempt to “shake loose” a problem on the lines, such as tree branches, animals, etc. Therefore you can have quite a few unnecessary engine starts with start programming set for less than 3 seconds. One concern, as most people are well aware, is that the majority of utility power bumps last less than 3 seconds. The only reason most facility managers would want the start signal sent to the generator in less than 3 seconds would be if the UPS was using something other than conventional batteries for short-term backup (typically 5-15 minutes), such as flywheels (typically only 7-20 seconds). Opinions range from 0.5 seconds to 30 seconds. The standby-generator start-time delay programming adjustment is controversial in the data center industry.

Data backup generator kicks in during