Learn how to correctly size an AVR for your needs. Understand KVA ratings, power factor, and how to calculate the right capacity for your home or industrial applications.
Why AVR Sizing Matters
Choosing the correct AVR capacity is critical for effective voltage protection. An undersized AVR will overload and fail to protect your equipment, while an oversized AVR represents unnecessary cost. YOKE offers AVRs ranging from 3KVA to 60KVA to match any application requirement. This guide will help you calculate the exact capacity you need.
Understanding KVA Ratings
KVA (Kilovolt-Amperes) is the apparent power rating of an AVR. Unlike watts which measure actual power, KVA includes both actual power and reactive power. For single-phase systems: KVA = (Volts × Amps) / 1000. For three-phase systems: KVA = (Volts × Amps × 1.73) / 1000. Most home appliances are rated in watts, so you need to convert: KVA = Watts / (Power Factor × 1000). For pure resistive loads (heaters, incandescent bulbs), power factor is 1.0. For inductive loads (motors, compressors), power factor is typically 0.7-0.8.
Step-by-Step AVR Sizing Calculation
Step 1: List all equipment to protect. Step 2: Get the wattage of each item (check nameplate or manual). Step 3: Apply the starting/peak current multiplier for motors: inductive loads need 2-3× their running watts during startup. Step 4: Sum all wattages. Step 5: Convert to KVA using power factor (typically 0.8). Step 6: Add 20-30% safety margin for future expansion and overload capacity. Example: Protecting a refrigerator (200W), air conditioner (1500W), and TV (100W) with motor loads: Total = (200+1500+100) × 2.5 (motor multiplier) = 4500W → 4500/(0.8×1000) = 5.6KVA → With 20% margin = 6.7KVA → Choose SVC-10KVA.
YOKE AVR Models and Applications
YOKE offers a complete range of AVR models: SVC-3KVA: Ideal for single appliances like refrigerators, TVs, or computers. Perfect for home offices. SVC-10KVA: Suitable for entire home appliances including air conditioners, washing machines, and multiple devices. SVC-30KVA: Designed for small commercial use, restaurants, shops with multiple appliances. SVC-50KVA to SVC-60KVA: Heavy-duty industrial AVRs for manufacturing equipment, CNC machines, production lines, and entire facilities.
Common Sizing Mistakes to Avoid
1. Ignoring motor starting currents: Motors draw 3-5× normal current at startup. 2. Not accounting for future expansion: Always add 20-30% capacity margin. 3. Mixing voltage classes: Ensure input voltage range matches your local grid (110V or 220V systems). 4. Forgetting power factor: Using PF=1.0 for motor loads underestimates required KVA. 5. Overlooking efficiency curves: AVRs operate most efficiently at 60-80% load. 6. Ignoring load type: Some equipment (laser printers, MRI machines) have unique power quality needs.
Not sure which AVR capacity you need? Contact YOKE for professional sizing guidance and competitive pricing.
Get Quote