PAT
Port Address Translation
A form of NAT that lets many internal connections share one public address by tracking transport ports.
In everyday business: Hundreds of users can browse the Internet through one public IPv4 address.
UPS DESIGN
UPS Sizing, Runtime and Installation Playbook
How to calculate protected load, check watts and VA, use manufacturer runtime data and avoid common UPS sizing mistakes.
Book 2 | Chapter 11
Chapter opening
Chapter 11 moves from the course overview into ups sizing, runtime and installation. The aim is not to memorise product menus or commands. The reader should understand what problem the technology solves, how it fits into the wider cabling, fibre, racks and power textbook, what normal operation looks like, and how to prove the result in the field.
The previous chapter introduced server rack build, airflow and cable management playbook. This chapter continues the sequence by focusing on ups sizing, runtime and installation playbook, so the reader can connect the architecture to a more specific operational problem.
Learning objectives
- Explain the main purpose of UPS Sizing, Runtime and Installation in plain language.
- Identify the components that must work together for the service to operate.
- Use evidence to separate a design problem from a configuration or physical fault.
- Describe the business impact of a failure and the evidence required for handover.
Why this matters in a real company
This subject matters because infrastructure infrastructure supports normal business operations. Understanding the design makes purchasing, troubleshooting and recovery decisions easier to explain and verify.
PLAIN ENGLISH
Technical terms used in this chapter
You do not need to memorise the jargon first. Understand what each term does and why somebody running a company would care about it.
PoE
Power over Ethernet
Technology that sends DC power and Ethernet data over the same twisted-pair cable.
In everyday business: A camera or access point can be installed with one network cable instead of a separate power outlet.
SAN
Storage Area Network
A dedicated storage network that presents block storage to servers.
In everyday business: Multiple servers can use centrally managed storage without treating it like a normal file share.
BUSINESS TRANSLATION
What this means outside the server room
This topic matters because technical infrastructure exists to support everyday business operations. Understanding the purpose makes it easier to choose the right design and justify the cost.
Firewall
What it means: A firewall controls which network connections are allowed between users, systems and external networks.
In normal business language: It is a security checkpoint between parts of the company network. It should allow legitimate work while blocking unwanted access.
Why the decision matters: Firewall rules should describe real business flows such as 'staff may reach accounting on HTTPS', not unexplained broad permits.
NAT
What it means: NAT changes IP addresses as traffic crosses a network boundary.
In normal business language: It is similar to a company switchboard: many internal extensions can share one public number.
Why the decision matters: NAT helps with address use and publishing services, but it is not a substitute for firewall security.
PoE
What it means: Power over Ethernet sends both data and electrical power over the same Ethernet cable.
In normal business language: A camera or access point can use one cable instead of separate network and power wiring.
Why the decision matters: PoE can simplify installation and UPS protection, but the switch power budget and cable quality still need to be designed.
SAN
What it means: A SAN provides block storage to servers over a dedicated storage network.
In normal business language: Instead of giving staff shared folders, it gives servers raw storage capacity that they can format and use as if it were local.
Why the decision matters: SANs suit workloads needing shared block storage, but they add complexity and should be chosen for a real requirement.
Chapter contents
11.1 Measure the load you actually intend to protect
Schneider Electric's UPS selector guidance recommends adding the expected power draw of the protected equipment and notes that nameplate ratings can be higher than real draw. For a professional design, use measured or manufacturer load data where possible and keep future expansion as a clearly stated planning assumption.
Watts and VA are different limits
A UPS normally has both a real-power limit in watts and an apparent-power limit in VA. The connected load must fit both limits. Do not size only from VA because a load can exceed the watt rating first.
Runtime cannot be guessed accurately from battery Ah alone
UPS runtime depends on battery system, inverter efficiency, battery condition, temperature and load. Use the manufacturer's runtime curve or selector for the exact UPS and load. If the manufacturer does not publish runtime for the model/load, state that runtime is unverified rather than inventing a number.
PoE changes UPS load
If a UPS protects a PoE switch, include the downstream powered devices in the expected switch input demand. A switch with many cameras or APs can draw much more under full PoE load than when tested empty on the bench.
Installation checks
- Confirm input plug/circuit requirements and local electrical installation requirements.
- Check output connector compatibility and PDU loading.
- Provide ventilation clearances required by the UPS manufacturer.
- Record battery installation date and replacement history.
- Configure network management and shutdown integration where required.
- Test a controlled power failure before handover.
Bypass and maintenance
For critical installations, consider how equipment will remain powered while the UPS is serviced. A maintenance bypass architecture must be designed for the actual electrical system and should be installed by appropriately qualified personnel.
Client benefit
Correct sizing gives the client predictable support for the intended load, avoids nuisance overload shutdowns and makes runtime expectations traceable to manufacturer data rather than sales estimates.
UPS & Power Knowledge Centre | Electrical Load and Heat Calculator | UPS categories at Server Warehouse
WORKED BUSINESS SCENARIO
Scenario: turn the technology into an operational service
A company depends on this technology every day. The technical configuration may be correct, but the real requirement is predictable operation, evidence when something fails and documentation another technician can understand.
What the chapter teaches us: Treat the subject as a service with a purpose, dependencies, normal behaviour, failure modes and a recovery method.
Think it through
- What business process depends on this component?
- What would normal operation look like?
- What evidence would prove the cause of a failure?
PRACTICAL WORK
Hands-on lab
Create a small isolated lab that reproduces the chapter's core architecture. Record the starting configuration, make one controlled change and prove the result with measurable evidence.
Troubleshooting exercise
Take one realistic failure, list the evidence you would collect before changing anything, then write the shortest fault-isolation path.
Chapter field checklist
- I can explain the subject without relying only on acronyms.
- I can draw or describe the main traffic, storage, power or service path.
- I know what normal operation should look like.
- I know which logs, counters or test results prove the result.
- I can explain the business impact if this component fails.
- I would document the final configuration and evidence at handover.
Chapter summary
UPS Sizing, Runtime and Installation Playbook should now be understood as a business service with a technical implementation, not simply a collection of commands or product names. The important habit is to know the purpose, understand the dependencies, measure the result and document what was proven.
END OF CHAPTER
Review questions
- Explain the subject in plain language to a business owner.
- List the main dependencies that must be healthy before this service can work.
- Describe one realistic failure and the first three pieces of evidence you would collect.
- Explain what should be documented at handover.
A good answer should explain the reason, not only repeat a product name or command.
Technical references
Training manual: turn load data into a defensible UPS selection
Step 1: build the protected-load schedule
| Equipment | Quantity | Expected W each | Expected VA each | Critical? |
|---|---|---|---|---|
| Firewall | User input | Verified input | Verified input | Yes / No |
| PoE switch | User input | Include planned PoE load | Verify | Yes / No |
| NVR / server | User input | Measured or published | Verify | Yes / No |
Step 2: check both ratings
The selected UPS must support both the total real power in watts and the total apparent power in VA. If only one of those values is known, the design is incomplete.
Step 3: apply project growth as an explicit assumption
If the client expects expansion, document the reserve separately. Example: current measured load 900 W, user-selected 25 percent planning reserve, planning load 1125 W. The 25 percent is a design assumption, not a universal standard.
Step 4: verify runtime
Use the exact manufacturer runtime table or selector for the chosen UPS at the planning load. Runtime is nonlinear, which is why battery capacity alone is not a reliable shortcut.
Step 5: test the whole chain
- Confirm normal utility operation.
- Record UPS load percentage and battery state.
- Perform a controlled input-power failure if the site permits.
- Confirm critical switches, firewall, storage and endpoints remain powered.
- Confirm network connectivity remains operational.
- Restore power and confirm normal recharge/online state.
Client benefit
The client receives a documented protection design with a traceable load, known capacity and runtime expectation from the manufacturer rather than a vague promise that "the UPS should last about an hour".