# Electrical Design Basis, Connected Load Analysis, BOQ & Capital Costing (INR) for Pharma & API Facilities

# 1. Executive Summary & Electrical Design Philosophy

In pharmaceutical Active Pharmaceutical Ingredient (API) synthesis and formulation manufacturing facilities, electrical power distribution is a critical, high-integrity utility that directly impacts:

1. Process Safety & Explosion Prevention: Over 70% of synthesis plant floor space is classified as ATEX / PESO Zone 1 / Zone 2 (Gas Group IIA, IIB, IIC) due to flammable solvent vapors (Methanol, Toluene, Acetone, Hexane, Hydrogen). Electrical equipment must feature certified Flameproof (Ex d / Ex db) or Increased Safety (Ex eb / Ex nA) construction.
2. Batch Criticality & 100% Power Reliability: An unannounced power outage during a high-temperature synthesis or cryogenic runaway reaction can cause solvent boiling, agitator stalling, batch solidification, or relief disc bursting. Facilities demand $N+1$ Transformer redundancy and 100% Emergency Diesel Generator (DG) synchronization.
3. Power Quality & Harmonic Distortion: Heavy usage of Variable Frequency Drives (VFDs) across reactor agitators, centrifuges, and chilling compressors generates severe harmonic distortion ($THD_i > 25\%$), demanding Form 4b Intelligent Motor Control Centers (iMCC), Active Harmonic Filters (AHF), and Detuned APFC Capacitor Banks.

This technical guide presents the complete electrical design basis, equipment load list analysis, substation sizing, cable engineering, and turnkey itemized Bill of Quantities (BOQ) in Indian Rupees (₹ INR) for a modern 3,000 m² Built-Up Area (BUA) API Synthesis & Formulation Block.

# 2. Plant Connected Electrical Load List & Maximum Demand Sizing

For a multi-tier commercial API synthesis facility comprising 12 Jacketed Reactors, 4 Bottom-Discharge Centrifuges, 2 Agitated Nutsche Filter Dryers (ANFD), 2 Rotary Cone Vacuum Dryers (RCVD), dedicated Chilling Plants, Air Compressors, and Cleanrooms:

# 2.1 Departmental Connected Load Breakdown

# 2.2 Maximum Demand & Transformer KVA Sizing

• Total Connected Load ($P_{conn}$): $1,585\text{ kW}$
• Total Operating Running Load ($P_{op}$): $1,047\text{ kW}$
• Average Operating Power Factor ($\cos\phi$): $0.90$ (lagging)
• Maximum Apparent Power Demand ($S_{max}$):

• Future Expansion & Contingency Margin: $+25\%$ allowance for future product synthesis lines:

• Selected Substation Architecture:
  • Main Utility Transformers: $2 \times 1,500\text{ kVA}$, $11\text{ kV} / 433\text{ V}$, Dyn11 Oil-Immersed / Cast Resin Dry-Type Transformers (Operating in $2 \times 50\%$ split or $1\text{ Working} + 1\text{ Standby}$ with automatic bus coupler).
  • Emergency Standby Power: $1 \times 1,500\text{ kVA}$ (or $2 \times 750\text{ kVA}$) Silent Diesel Generator (DG) Skid with auto-mains failure (AMF) synchronization.

# 3. High Tension (HT) & Low Tension (LT) Power Distribution Architecture

                       [ 11 kV State Grid Incomer (Discom) ]
                                      │
                         [ 11 kV HT VCB Switchgear Panel ]
                                      │
              ┌───────────────────────┴───────────────────────┐
              │                                               │
   [ Transformer-1: 1500 kVA ]                    [ Transformer-2: 1500 kVA ]
   ( 11 kV / 433 V, Dyn11 )                       ( 11 kV / 433 V, Dyn11 )
              │                                               │
   [ Incomer ACB-1: 2500A 4P ]                     [ Incomer ACB-2: 2500A 4P ]
              │                                               │
              └────────────[ Bus Coupler: 2500A 4P ]──────────┘
                                      │
                   [ Main LT Power Control Center (PCC) ]
                   ( 50 kA / 1 sec, Form 4b Compartment )
                                      │
         ┌────────────────────────────┼────────────────────────────┐
         │                            │                            │
[ 600 kVAR Detuned APFC ]    [ Process iMCC / VFD Panel ]   [ Utility & HVAC MCC ]
( 7% Detuned Reactors )      ( Reactors, Centrifuges )      ( Chillers, Air Comp )

# 3.1 Main LT Power Control Center (PCC) Specifications

• Busbar Rating: Electrolytic Grade Aluminium ($E91E$) or Copper ($99.9\%$ IACS), rated for $2,500\text{ A}$ continuous duty with heat-shrinkable PVC sleeving and color-coded phase identifiers.
• Short-Circuit Fault Rating: $50\text{ kA}$ for $1.0\text{ second}$ per IS 8623 / IEC 61439-1/2.
• Air Circuit Breakers (ACBs): 4-Pole, Draw-out type, Electrically operated (EDO), Microprocessor-based trip release ($LSIG$ — Long time, Short time, Instantaneous, Ground fault).
• Enclosure Degree of Protection: IP 54 for indoor MCC room; Form 4b compartmentalization separating busbars, cable terminations, and functional switch units.

# 4. Intelligent Motor Control Centers (iMCC) & Variable Frequency Drives (VFDs)

In API manufacturing, precise variable speed control of reactor agitators and centrifuges is mandatory for batch recipe management:

Interactive Engineering Tool: Size cables, evaluate voltage drops, and check motor starting current using our interactive Electrical Cable Sizing & Voltage Drop Calculator.

# 5. Cable Sizing Mechanics, Derating Factors & Voltage Drop Engineering

Cable selection in industrial chemical blocks is governed by three mandatory engineering criteria:

# 5.1 Criteria 1: Continuous Ampacity & Derating Formula

Where:

• $I_{FL} = \frac{P_{kW} \times 1000}{\sqrt{3} \times V_L \times \cos\phi \times \eta}$ = Full Load Current ($A$)
• $k_{temp}$ = Ambient temperature derating factor ($0.88$ for $45^\circ\text{C}$ in air per IS 3961)
• $k_{group}$ = Grouping factor for multiple cables touching on perforated tray ($0.70 - 0.80$)
• $k_{depth}$ = Burial depth factor ($0.95$ for $1.0\text{ m}$ depth)

# 5.2 Criteria 2: Steady-State & Motor Starting Voltage Drop

• Maximum Allowed Steady-State Voltage Drop: $\le 3.0\%$ (from MCC to motor terminal).
• Maximum Allowed Motor Starting Voltage Drop (DOL/Star-Delta): $\le 10.0\% - 12.0\%$ (at $I_{start} \approx 6.0 \times I_{FL}$).

# 5.3 Criteria 3: Short-Circuit Thermal Withstand

Where:

• $I_{sc}$ = Prospective short-circuit fault current ($50\text{ kA}$ at PCC, $25\text{ kA}$ at Sub-MCC)
• $t$ = Fault clearing duration ($0.1 - 0.2\text{ sec}$ for breaker/fuse clearing)
• $K$ = Material constant ($143\text{ A}\cdot\text{s}^{1/2}/\text{mm}^2$ for Copper/XLPE, $94\text{ A}\cdot\text{s}^{1/2}/\text{mm}^2$ for Aluminium/XLPE)

# 6. Hazardous Area Flameproof (Ex-d) & Earthing Grid Engineering

# 6.1 ATEX / PESO Hazardous Area Installation Rules

1. Double Compression Flameproof Brass Cable Glands: All cable entries into Ex-d junction boxes, motors, and push-button stations must use certified Ex-d double compression brass glands with neoprene inner and outer seals.
2. Local Control Stations (LCS): Flameproof Cast Aluminium / Cast Iron start/stop/emergency push button stations with ammeters (Ex d IIC T4, IP 65).
3. Cleanroom LED Luminaires: Flameproof (Ex d) or Increased Safety (Ex e) bottom-opening cleanroom LED light fixtures providing $\ge 350\text{ Lux}$ at 1-meter floor level.

# 6.2 Earthing Grid & Lightning Protection (IS 3043 / IS 2309)

• Main Power Earthing Grid: $50 \times 6\text{ mm}$ Galvanized Iron (GI) or $50 \times 6\text{ mm}$ Bare Copper tape buried at $1.0\text{ m}$ depth around the plant perimeter with maintenance-free chemical copper earth pits ($\le 1.0\ \Omega$ grid resistance).
• Clean Instrument & PLC Earthing: Dedicated isolated copper earth pits ($\le 0.5\ \Omega$ resistance) completely isolated from power earth.
• Vessel Electrostatic Earthing: Every reactor, receiver, centrifuge, and filter must have 2 independent M10 earthing bosses bonded to the earth grid ($< 5.0\ \Omega$ loop resistance per NFPA 77).

# 7. Turnkey Electrical Bill of Quantities (BOQ) & Capital Costing (INR)

Below is the complete, itemized electrical capital expenditure budget for a 3,000 m² BUA API Synthesis & Formulation Block (1,500 kVA Substation):

# Itemized Electrical BOQ & Budget Breakdown (₹ INR)

# 7.1 Capital Cost Metric Benchmarks

• Total Turnkey Electrical Cost: ₹5.46 Crores (₹545.53 Lakhs)
• Unit Cost per Square Foot of BUA: ₹1,690 / sq. ft BUA ($32,290\text{ sq. ft} \approx 3,000\text{ m}^2$)
• Unit Cost per kVA of Installed Capacity: ₹36,368 / kVA ($1,500\text{ kVA}$)

# 8. Summary & Key Engineering Takeaways

1. Safety First: Flameproof Ex-d certified drives, double compression brass glands, and dual M10 earthing bosses are non-negotiable in solvent synthesis areas.
2. Harmonic Mitigation: Heavy VFD integration requires detuned APFC reactors (7% tuning for 5th harmonic) to prevent capacitor overheating and maintain utility grid compliance ($THD_v \le 5\%$).
3. Rigorous Cable Sizing: Always size industrial cables by cross-verifying Ampacity, Steady-State $\%VD \le 3\%$, Motor Starting $\%VD \le 12\%$, and Short-Circuit Withstand $A_{\min} = \frac{I_{sc}\sqrt{t}}{K}$.

# 9. Governing National & International Reference Standards

• IS 732:2019: Code of Practice for Electrical Wiring Installations.
• IS 1255:1983: Code of Practice for Installation and Maintenance of Power Cables up to and including 33 kV Rating.
• IS 3043:2018: Code of Practice for Earthing.
• IS 2309 / IEC 62305: Protection of Buildings and Allied Structures against Lightning.
• IS / IEC 60079 (Parts 0 to 14): Explosive Atmospheres — Equipment Protection, Classification, and Electrical Installations.
• IS 8623 / IEC 61439-1/2: Low-Voltage Switchgear and Controlgear Assemblies (Type-tested Form 4b panels).
• IS 12615:2018 / IEC 60034-30: Line Operated Three-Phase Induction Motors — Energy Efficiency Classes (IE3 / IE4).
• IEEE 141 (Red Book): Recommended Practice for Electric Power Distribution for Industrial Plants.
• NFPA 70 (NEC): National Electrical Code (Hazardous Locations Article 500-505).
• Central Electricity Authority (CEA) Regulations 2010: Measures Relating to Safety and Electric Supply.

# Applicable Engineering Standards & Codes Used

The engineering methodologies, design correlations, and safety criteria detailed in this article adhere to the following international standards and industry codes:

• US FDA 21 CFR Part 211: Current Good Manufacturing Practice for Finished Pharmaceuticals
• EU GMP Annex 1: Manufacture of Sterile Medicinal Products
• ISPE Baseline Pharmaceutical Engineering Guide (Vol 1-7: Bulk Active Pharmaceutical Ingredients, Water & Steam Systems): ISPE Baseline Pharmaceutical Engineering Guide (Vol 1-7: Bulk Active Pharmaceutical Ingredients, Water & Steam Systems)
• WHO Technical Report Series No. 961: Supplementary Guidelines on Good Manufacturing Practices for Heating, Ventilation and Air Conditioning