Do the On-Line UPS models have an internal automatic bypass?

[CoBbler]

A UPS failure recently caused a major issue with some critical equipment, and our folks are now researching alternate UPS options. I'm trying to get some research done and stay ahead of it as we would like to keep everything APC brand. A link that is getting sent around mentions automatic bypass switches, AKA "safe failure to mains" https://www.constantpowerservices.com/questions/6-what-does-a-bypass-switch-in-a-ups-system-do 

It looks like the APC On-Line UPS models have this feature, but I need to provide some proof. The PDFs for the On-Line models mention a Bypass Type, which is not present in the Line Interactive model documentation.

APC Smart-UPS On-Line 1000VA - Bypass Type: Built-in Bypass

APC Smart-UPS On-Line 3kVA Rackmount 2U - Bypass Type: Internal Bypass (Automatic and Manual) 

Is this the automatic bypass feature we are looking for?

[Teken]

Just to provide some clarity and insight to the topic at hand. When critical infrastructure needs to be powered 24.7.365 these systems are connected to a ATS (Automatic Transfer Switch). For the highest level of fail over and redundancy the ATS is connected to (2) separate Online UPS which is connected to a different power source like a standby generator. Should there be a fault in one of the UPS the ATS will transfer power to the other unit.

A maintenance bypass is intended to allow a person to transfer key loads to a alternate AC source while the UPS / Other is being serviced or replaced.

The internal bypass inside a UPS allows a person to receive power only from the AC mains. This essentially removes any conversion / battery protection from the output. You’ll need to sit down and really think how that would help you or anyone (IF) the UPS was faulty regardless if you could enable a bypass?? 

Only a ATS / Maintenance Bypass will provide redundancy, fail over, and backup.

Rock On . . . 🤟

[CoBbler]

Thank you for the reply, this is really useful and I'll convey these concepts to the powers that be. The facility is protected by generator power with an ATS, so there was confusion as to how a little 1kVA UPS could cause a near disaster. 

Sounds like the combination of an On-Line UPS in the equipment cabinet, with a manual bypass switch is the way to go. Gives the operators every option for troubleshooting.

[Teken]

Keep in mind a ATS will operate automatically without human intervention. The power source can be selected anytime manually or remotely should the need arise. The ATS also offers a tremendous amount of insight because it can be connected to the network.

Having a NMS (Network Monitoring System) that tracks, monitors, and stores via SNMP data offers more information. When SNMP Traps are configured and enabled current and pending failures can be acted on in a timely manner along with receiving time stamped emails which can be prioritized to team members.

A manual bypass requires an onsite person to intervene and switch over if there’s a fault / failure. They offer no networking connectivity to help track and monitor present and historic faults / failures.

Your team will need to determine what is an acceptable amount of downtime if a manual transfer switch is chosen instead of a ATS. 

[dpierce4776]

Also to add to what @Teken stated. The manual bypass in the 1K is really only for emergencies like in the rare cases that power will still flow though the unit, but in many cases when the 1K dies it dies.

The APC ATS like the AP4450A is automatic and we use them a lot. It is rack mountable  has two different input sources. Which one is usually from a UPS system and the other is from a second UPS system or battery power. These will swap inputs automatically and 99.99999% of the time without dropping the load. This will protect you if the UPS were to take a hit and go out but keep the gear up and running.

Also most, if not all, large ATSs that are connected to an outside generator are "break before make" which means that there is a slight moment in time where your gear may not have power. If there is a UPS behind that then you should be OK but UPSs fail as well and batteries go bad. Which is why most places feed a stand alone PDU from each of the UPS and they have and STS (static transfer switch) or and ATS (Automatic transfer switch) built in. This allows 1 UPS large (20K or higher) to go go down and automatically switch the load to the other UPS.