5.2 Backup Power & UPS Systems

Grid stability is a variable, not a constant. In electronics manufacturing, a 50ms power sag does not just reset a clock; it scraps active wafers, jams SMT pick-and-place heads, and corrupts server databases. Backup power is not an insurance policy; it is an active subsystem of the production line that must seamlessly bridge the gap between grid failure and generator stabilization.

UPS Topology & Load Segmentation

Do not put the entire facility on a single UPS. This creates a single point of failure and wastes capacity on non-critical loads (e.g., cafeteria lights).

• If Load is Critical IT (Server Room) -> Then Deploy Online Double Conversion UPS (N+1).
  • Physics: Zero transfer time. The load runs constantly off the inverter, completely isolating it from grid noise and frequency drift.
• If Load is Production Machines (SMT/Reflow) -> Then Deploy Line-Interactive UPS.
  • Constraint: Sizing must account for Inrush Current (approx. 6x steady state) when motors restart. A standard kW rating is insufficient; size by kVA.
• If Load is Facilities (HVAC/Compressors) -> Then Do not use UPS. Connect directly to Diesel Generator with Soft Start.

Pro-Tip: Battery health is non-linear. A "5-year" VRLA battery will fail in 3 years if the ambient temperature stays at 25˚C. For every 8˚C rise above 20˚C, battery life is cut in half. Keep your UPS room at 20˚C strictly.

Generator Operations

The generator is the long-duration power source. The UPS only buys time (typically 15 minutes) for the generator to start and stabilize.

• If Grid Fails -> Then Automatic Transfer Switch (ATS) must trigger Generator Start within < 10 seconds.
• If Generator is Running -> Then Fuel capacity must support ≥ 24 Hours of continuous operation at 80% load.
  • Constraint: Fuel degrades. Implement a fuel polishing program to filter water and microbial growth every 6 months.
• If Generator is Idle -> Then Block Heater must keep the engine block at 40˚C.
  • Reason: Cold starts under load cause catastrophic piston wear and frequency instability during the critical first minute.

Maintenance & Testing Protocol

A generator that starts during a monthly test with no load is not a verified backup. It is a "False Positive."

• Weekly: No-Load Run (10 minutes). Verifies starting logic and battery health.
• Monthly: On-Load Run (30 minutes). Transfer facility load to generator to verify ATS switching and thermal stability.
• Annually: Load Bank Test (4 Hours). Run at 100% capacity using an external resistive load bank to prevent "Wet Stacking" (unburned fuel buildup in the exhaust).

Final Checklist

Parameter	Metric / Rule	Critical State
Server Room UPS	Topology	Online Double Conversion
UPS Room Temp	Setpoint	20˚C ± 2˚C
Generator Start	Time to Stable	< 10 Seconds
Fuel Capacity	Runtime	≥ 24 Hours
Load Bank Test	Frequency	Annual (100% Load)
ATS Logic	Transfer Priority	Break-Before-Make
Battery Life	Replacement	Every 3 – 4 Years