أنظمة الـ UPS

A) For Regular Users

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• Calculate your load (W): Convert to VA → VA ≈ W ÷ Power Factor (pf)
  (if unknown, assume pf = 0.7–0.8).
  
  
• Add a safety margin: Always choose a UPS with 20–30% more
  capacity than your total load.
  
  
• Decide on runtime: How long do you need backup?
  (e.g., 10–15 mins to shut down safely).
  
  
• Pick the right topology: Line-Interactive for home/office use;
  Online for highly sensitive equipment.
  

Example

PC (300W) + Monitor (60W) + Router (20W) = 380W.

With pf=0.8 → 475 VA.

Add 30% margin → ~650 VA.

So, choose a 700–1000 VA UPS for comfort.

B) For Engineers & IT Managers

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• Topology:
  
  
• Normal office with moderate fluctuations → Line-Interactive.
  
  
• Mission-critical or zero-downtime environments → Online
  (Double Conversion).
  
  
  
• Key Specs to Check:
  
  
• Capacity (kVA) with Power Factor (0.9 recommended).
  
  
• Low Total Harmonic Distortion (THD) output.
  
  
• Crest factor for devices with high inrush currents.
  
  
• Scalability (modular, N+1 redundancy).
  
  
• Monitoring & control (USB/SNMP).
  
  
• Battery type (VRLA vs. Li-ion), lifespan, and temperature ratings.
  
  
• Compliance with medical/industrial standards.

C) Common Mistakes to Avoid

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• Buying a UPS too close to your actual load (no margin).
  
  
• Ignoring required runtime.
  
  
• Forgetting startup/inrush currents of some devices.
  
  
• Overlooking environmental conditions (heat, dust, ventilation).