Short answer. Isolating a UPS safely depends on doing the steps in the manufacturer’s order, because the system has several power paths and stored energy in batteries and capacitors. Showing one step at a time, in a fixed order, helps crews follow that sequence.
Definition. A UPS (uninterruptible power supply) is a system that supplies power to critical loads without interruption when the main source fails, using stored energy such as batteries.
The main parts of a UPS system
- Rectifier. Converts incoming AC power to DC, to charge the batteries and feed the inverter.
- Inverter. Converts DC back to clean AC for the critical load.
- Static bypass. An electronic switch that can move the load straight to the bypass source if the inverter cannot carry it.
- Maintenance bypass. A manual path that lets the load stay powered while the UPS module itself is isolated for work.
- Batteries. Store the energy that carries the load when input power is lost. They stay energized when the UPS is switched off.
Why order matters
A UPS has more than one path to the load, and more than one source of energy. Opening a breaker in the wrong order can drop the critical load, or transfer it onto a path that is not ready. And switching off the UPS does not make it safe: batteries and DC capacitors can hold dangerous energy. NFPA 70E-2024 120.6 includes releasing stored electrical energy as part of establishing an electrically safe work condition.
Always integrate the manufacturer’s procedure into your site MOP
UPS designs differ between manufacturers, models and sites. Isolation must follow the manufacturer’s procedure, integrated into your approved site MOP, written for that installation. This guide deliberately does not give a generic step list, because a generic list is not a procedure for your equipment.
What a good UPS isolation procedure includes
- The exact equipment names as labeled, and the starting state of each breaker and switch.
- The expected state after each step, so the crew can confirm before moving on.
- Hold/QA points before load transfer and before any work on stored-energy parts.
- The verification of absence of voltage, including on DC parts, before work starts.
- A back-out plan if the load does not transfer as expected.
Where ICARUS Ops fits
The ICARUS Ops Error Elimination System (EES) shows UPS isolation card by card, in a fixed order: one step at a time, steps that cannot be reordered, and a photo, reading or QA sign-off at critical steps, even with no signal. Photo or other verification can be captured at critical steps to confirm the proper state.
See a sample ICARUS Ops EES procedure
See a sample ICARUS Ops EES procedure
Demos are for teams actively evaluating software for deployment.