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GENERATOR SIZING CALCULATION

This report presents a comprehensive generator sizing analysis based on connected loads, diversity factors, and motor starting requirements for the specified facility.

Running Load Analysis

Sum of 4 connected load(s)

Formula: $$ S_{connected} = \sum \frac{P_{kW,i} \times DC_i}{PF_i} \times n_i $$
Result: $$ = 211.08 \; \text{kVA} $$

Diversity factor 0.75 applied for manufacturing facility

Formula: $$ S_{diversified} = S_{connected} \times DF $$
Substitution: $$ = 211.08 \times 0.75 $$
Result: $$ = 158.31 \; \text{kVA} $$

Weighted average power factor of all connected loads

Formula: $$ PF_{overall} = \frac{P_{total,kW}}{S_{total,kVA}} $$
Substitution: $$ = \frac{181.60}{211.08} $$
Result: $$ = 0.860 $$

Load Inventory

Connected load inventory: * Process Pump: 55.0 kW x 2 (PF=0.86, DC=1.00) = 127.91 kVA * Air Compressor: 37.0 kW x 1 (PF=0.85, DC=0.80) = 34.82 kVA * Ventilation Fans: 7.5 kW x 4 (PF=0.84, DC=1.00) = 35.71 kVA * Lighting: 12.0 kW x 1 (PF=0.95, DC=1.00) = 12.63 kVA

Starting Load Analysis

Air Compressor (37.0 kW) with DOL starting

Formula: $$ S_{start} = P_{motor} \times k_{start} $$
Substitution: $$ = 37.0 \times 6.0 $$
Result: $$ = 222.00 \; \text{kVA} $$

Largest motor starting plus diversified background load

Formula: $$ S_{demand} = S_{start} + S_{background} $$
Substitution: $$ = 222.00 + 158.31 $$
Result: $$ = 380.31 \; \text{kVA} $$

Generator Selection

Sizing basis: Starting load (380.31 kVA) with 25% safety margin

Formula: $$ S_{required} = S_{basis} \times SM $$
Substitution: $$ = 380.31 \times 1.25 $$
Result: $$ = 475.39 \; \text{kVA} $$

Next standard size above 475.39 kVA

Result: $$ S_{gen} = 500 \; \text{kVA} $$

Generator Utilization

Normal operating load as percentage of generator capacity

Formula: $$ U_{running} = \frac{S_{diversified}}{S_{gen}} \times 100 $$
Substitution: $$ = \frac{158.31}{500} \times 100 $$
Result: $$ = 31.7 \% $$

Peak demand during motor starting as percentage of generator capacity

Formula: $$ U_{peak} = \frac{S_{required}}{S_{gen}} \times 100 $$
Substitution: $$ = \frac{380.31}{500} \times 100 $$
Result: $$ = 76.1 \% $$

Fuel Consumption

Based on 0.25 L/kWh diesel consumption at 31.7% load factor

Formula: $$ F = S_{gen} \times 0.8 \times LF \times 0.25 $$
Substitution: $$ = 500 \times 0.8 \times 0.317 \times 0.25 $$
Result: $$ = 31.7 \; \text{L/hr} $$

Recommendations

Engineering recommendations based on the analysis: **1. Install soft starter on Air Compressor** Reduce generator from 500 kVA to 350 kVA **2. Low generator utilization** Generator will run at only 31.7% capacity Risk of wet stacking in diesel engines. Consider smaller unit or load management.
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