Standby power systems — generators, transfer switches, and the sequencing logic between them — are what actually carries a facility through a utility outage. This course covers standby power system fundamentals: automatic transfer switches, sequencing, and the maintenance that keeps them ready.
You'll leave able to explain the failure points most likely to prevent a successful transfer, before they're tested by a real outage.
What You'll Learn
- Understand how standby power systems sequence during a utility outage
- Explain automatic transfer switch operation and testing
- Apply maintenance practices that keep standby systems ready
- Recognize the failure points most likely to prevent a successful transfer
Course Modules
Standby Power System Overview
How generators and transfer switches work together during an outage.
Automatic Transfer Switches
Operation, testing, and common failure points.
Sequencing & Coordination
Making sure standby systems come online in the right order.
Maintenance for Readiness
Keeping standby systems ready for the outage that hasn't happened yet.
Why This Matters in a Data Center
When utility power fails, the UPS carries the load for minutes. Standby generators and automatic transfer switches (ATSs) keep the facility running beyond that. If a generator fails to start, a transfer switch sticks or the sequencing logic is wrong, the UPS batteries run down and the site goes dark.
Standby power systems are covered by several standards. The National Electrical Code separates emergency systems (Article 700), legally required standby (Article 701) and optional standby (Article 702), and NFPA 110 covers the performance, testing and maintenance of emergency and standby power systems. This course covers how standby systems are laid out, how ATSs work, how sequencing and load coordination are set up, and the maintenance that keeps the system ready.
Who This Course Is For
Audience: Facilities technicians responsible for standby and emergency power systems.
Course Details
Frequently Asked Questions
What does an automatic transfer switch do?
An ATS monitors the normal power source. When it fails, the ATS signals the generator to start and transfers the load once generator voltage and frequency are stable. When utility power returns, it transfers the load back and lets the generator cool down.
What is the difference between open and closed transition transfer?
Open transition briefly disconnects the load before connecting it to the other source (break-before-make). Closed transition briefly parallels the two sources so the load is not interrupted (make-before-break), which requires additional controls and utility approval in many cases.
How often should standby generators be tested?
NFPA 110 requires regular exercising and inspection, commonly monthly under load for Level 1 systems, plus periodic longer tests. The exact requirements depend on the system's classification and local rules, which the Maintenance for Readiness module explains.
Which OSHA standards apply to emergency and standby power systems?
OSHA's electrical standards in 29 CFR 1910 Subpart S apply, including 1910.308(b) on emergency power systems, along with the electrical safety-related work practice rules (1910.331 to 1910.335) and lockout/tagout (1910.147) for maintenance. Design and testing requirements mostly come from codes your jurisdiction adopts, such as NEC Articles 700, 701 and 702 and NFPA 110.