Substation Engineering Solutions in Bangladesh
From rural electrification to heavy textile mills, pharmaceutical plants, commercial high-rises, and power utility interconnection (BREB, DPDC, DESCO, WZPDCL, NESCO).
11/0.415kV Indoor Substations
Standard commercial and industrial installations consisting of HT VCB/LBS switchgear, oil-immersed or dry-type cast resin transformer, LT distribution board, and automatic PFI plant inside an engineered electrical substation room.
33/11kV Primary Grid Substations
Heavy-duty step-down utility substations engineered for industrial economic zones (EZ), export processing zones (EPZ), and distribution utilities. Features outdoor gantry, 33kV VCB breakers, power transformers with OLTC, and Control & Relay Panels (CRP).
Compact Unit Substations (USS)
Factory-assembled outdoor weatherproof kiosk substations combining MV Ring Main Unit (RMU), distribution transformer, and LV panel in a compact steel enclosure. Available with or without transport wheels for rapid on-site commissioning.
Pole-Mounted Distribution Units
BREB and utility-standard pole-mounted substations up to 250kVA mounted on twin concrete poles (H-frame / SPC poles) with 11kV Drop Out Fuses, Lightning Arrestors, and low-voltage pole-mounted distribution boxes.
11/0.415kV Substation Single-Line Architecture (SLD Flow)
The electrical architecture of a standard 11/0.415kV distribution substation follows a systematic protection and transformation chain designed to isolate faults, regulate power factor, and safeguard human lives:
11kV Utility Feed
Underground 11kV XLPE cable or overhead line from BPDB/BREB/DPDC/DESCO.
LA & DOF Protection
Surge/Lightning Arrestors (ZnO) and Drop Out Fuse for short-circuit clearance.
HT Switchgear (VCB/LBS)
12kV ABB VD4 Vacuum Circuit Breaker or Load Break Switch with CT/PT metering.
Power Transformer
Step-down 11/0.415kV ONAN oil-cooled (50kVA–3000kVA, Dyn11 vector).
Grounding Grid
Exothermic Cadweld copper earth mesh achieving total impedance R < 1.0 Ω.
LT Switchgear
Air Circuit Breaker (ACB) / MCCB incomer, segregated copper busbar & meters.
PFI Plant
Microprocessor automatic capacitor bank compensating Cos φ to 0.98+.
Distribution (BBT)
Busbar Trunking System or heavy sub-distribution boards to load centers.
Substation Equipment & Materials Directory
Manufactured and supplied with high-grade components from world-leading engineering brands (ABB, Schneider Electric, Savita, Fuji Electric, Mikro, EPCOS).
Power & Distribution Transformers
In-house designed distribution transformers combining Japanese CRGO silicon core, 99.9% electrolytic copper coils, and mineral oil cooling.
- Capacity Range: 50 kVA up to 3000 kVA
- Voltage Class: 11kV, 33kV / 0.415kV (Dyn11)
- Cooling Type: ONAN / ONAF & Cast Resin Dry
- Standards: IEC-76, BS-171, VDE 0537
HT Switchgear Panels (VCB & LBS)
12kV & 36kV indoor vacuum switchgear equipped with authentic ABB (Italy) VD4 fixed or withdrawable circuit breakers and FN12 Load Break Switches.
- Rated Voltage: 12 kV / 36 kV
- Rated Current: 630 A to 1250 A / 2500 A
- Breaking Capacity: Up to 31.5 kA (3 sec STC)
- Interrupter: ABB VD4 Ceramic Vacuum
LT Switchgear Distribution Panels
Low tension distribution board engineered for central facility power distribution, housing ACB, MCCB, and multi-cubicle copper busbars.
- Incomer Breakers: ACB 800A to 6300A (Air Circuit)
- Feeder Protection: MCCB 10A–1600A & MCB
- Busbar System: Electrolytic Copper Busbar (Tinned)
- Finishing: 7-Tank Hot Phosphate Powder Coat
Automatic PFI Plants (Power Factor)
Eliminates low power factor utility penalties by continuously monitoring phase angle and switching dry capacitor stages dynamically.
- Capacitor Steps: 5 KVAR up to 1200 KVAR Banks
- Total Capacity: Up to 10,000 KVAR Output
- Controller: Microprocessor PFC Relay (Mikro/EPCOS)
- Harmonics: Detuned Filter Reactors (7% / 14%)
Instrument Transformers (CT & PT)
High-precision Current Transformers and Potential Transformers for revenue billing metering and protection relay actuation.
- Voltage Level: 11kV & 33kV Indoor/Outdoor
- Metering Accuracy: Class 0.2s, 0.5 Revenue Grade
- Protection Class: 5P10, 5P20 High Burden
- Insulation: Epoxy Cast Resin / Porcelain Shed
Lightning Arrestors & Drop Out Fuses
Outdoor yard primary protection protecting substation assets from atmospheric lightning strikes, switching surges, and overcurrents.
- Lightning Arrestor: ZnO Gapless 9kV/12kV/36kV (5kA/10kA)
- Drop Out Fuse (DOF): 11kV/15kV Rated (100A/200A, 75kV BIL)
- Insulator Body: High-Creepage Porcelain or Polymer
- Interrupting Current: 10 kA RMS Symmetrical
Substation Grounding Grid (R < 1Ω)
Comprehensive IEEE 80 compliant earth mesh using heavy stranded bare copper cables and molecular exothermic CAD-welded cross joints.
- Conductor Size: 70 mm², 95 mm², 120 mm² Bare Copper
- Jointing Method: Exothermic Cadweld Powder & Molds
- Target Resistance: R < 1.0 Ohm Guaranteed
- Bonding: All transformer tanks, cubicles & fences
Busbar Trunking Systems (BBT) & HT Cables
High-current sandwiched busbars replacing congested power cable trays between transformer secondary and main low-tension switchboards.
- BBT Capacity: 630A up to 5000A Sandwich Design
- HT Cables: 11kV & 33kV XLPE Armored Power Cables
- Cable Terminations: Heat-Shrink / Cold-Shrink Kits (Raychem)
- Ingress Protection: IP54 to IP66 Certified Enclosures
Control & Relay Panels (CRP) & DC Systems
Complete protection automation housing numerical relays, trip circuit supervision, and DC battery chargers for uninterruptible trip power.
- Protective Relays: 50/51 Overcurrent, 50N/51N Earth Fault
- Unit Protection: 87T Differential, 64R Restricted Earth
- Auxiliary DC Supply: 110V DC / 24V DC Battery & Float Charger
- Automation Protocol: IEC 61850 SCADA Ready Integration
Standard Technical Performance Specifications
Grounded in empirical factory testing per IEC-76, BS-171, and BSTI regulatory standards.
11/0.415kV Oil-Immersed Distribution Transformer Specifications (SETB Manufacturing)
| Capacity (kVA) | No-Load Loss (W) | Full-Load Loss (W) | Impedance (% Imp.) | Efficiency (Full Load %) | Dimensions (H x L x W cm) | Oil Capacity (L) | Total Weight (kg) |
|---|---|---|---|---|---|---|---|
| 100 kVA | 240 W | 1340 W | 4.0 % | 98.57 % | 132 x 100 x 65 | 221 L | 850 kg |
| 200 kVA | 380 W | 2250 W | 4.0 % | 98.37 % | 150 x 112 x 93 | 300 L | 975 kg |
| 250 kVA | 460 W | 2900 W | 4.5 % | 98.48 % | 158 x 123 x 95 | 270 L | 1100 kg |
| 315 kVA | 540 W | 3200 W | 4.5 % | 98.38 % | 157 x 120 x 97 | 400 L | 1250 kg |
| 500 kVA | 790 W | 4980 W | 5.0 % | 98.57 % | 165 x 124 x 102 | 550 L | 1725 kg |
| 630 kVA | 910 W | 6000 W | 6.0 % | 98.62 % | 170 x 136 x 103 | 620 L | 2025 kg |
| 800 kVA | 990 W | 7100 W | 6.0 % | 98.61 % | 225 x 170 x 113 | 725 L | 2625 kg |
| 1000 kVA | 1180 W | 8200 W | 6.5 % | 98.67 % | 215 x 185 x 115 | 850 L | 2900 kg |
| 1500 kVA | 1630 W | 12400 W | 6.5 % | 98.97 % | 230 x 200 x 120 | 1300 L | 4450 kg |
| 2000 kVA | 1950 W | 15500 W | 6.5 % | 99.04 % | 250 x 210 x 135 | 1700 L | 4900 kg |
| 2500 kVA | 2350 W | 18000 W | 7.0 % | 99.08 % | 285 x 220 x 150 | 2200 L | 6800 kg |
| 3000 kVA | 2950 W | 24500 W | 7.0 % | 99.08 % | 290 x 230 x 160 | 2700 L | 7500 kg |
11kV High Tension Switchgear Parameters: Vacuum Circuit Breaker (VCB) vs. Load Break Switch (LBS)
| Technical Parameter | Vacuum Circuit Breaker (VD4 VCB) | Load Break Switch (FN12 LBS) | Engineering Significance |
|---|---|---|---|
| Rated Operational Voltage | 12 kV (Applicable up to 36 kV) | 12 kV (Applicable 3.3kV–36kV) | Standard distribution voltage in Bangladesh. |
| Rated Normal Current | 630 A to 1250 A / 2500 A | 630 A | Continuous load-carrying capacity of busbars. |
| Short-Circuit Breaking Current | Up to 31.5 kA / 44 kA peak | Fuses provide breaking up to 31.5 kA | Safe clearance of catastrophic grid short-circuits. |
| Short-Time Withstand (3 sec) | 26.2 kA / 31.5 kA RMS | 31.5 kA with HRC Fuse | Withstand thermal energy during downstream faults. |
| Operating Duty & Life | 30,000 Mechanical Operations | Fast Snap-Action Make & Break | Long lifecycle with zero vacuum contact restrike. |
| Primary Arc Quenching | Vacuum Bottle (ABB Italy VD4) | Arc Chutes with Gas Evolution | Zero fire hazard compared to old oil circuit breakers. |
Mandatory Substation Pre-Commissioning Testing Protocols
Prior to utility energization, SETB’s testing engineers perform the full statutory battery of pre-commissioning tests in compliance with OCEI (Office of the Chief Electric Inspector), BSTI, and BUET standards using calibrated Megger test sets:
1. Insulation Resistance (MΩ)
2.5kV/5kV Megger test on HT windings to earth, HT to LT, and LT to earth ensuring zero moisture degradation.
2. High Voltage (HV) Withstand
28kV/35kV RMS power-frequency overvoltage applied for 60 seconds to verify solid insulation integrity.
3. Oil Dielectric Breakdown (BDV)
Oil sample testing across 2.5mm spherical gap per IEC 296 Class 1; must pass breakdown threshold > 40 kV.
4. Turns Ratio & Vector Group
Verification of voltage transformation ratio across all tap positions and Dyn11 30-degree phase shift angle.
5. Secondary Injection Relay Tests
Calibration of overcurrent, earth fault (50/51) curves, pickup thresholds, and VCB shunt trip coil operation.
6. Ground Resistance (Fall of Potential)
Four-terminal earth tester verification confirming entire substation earth grid satisfies R < 1.0 Ω.
SETB Substation Operations in Bangladesh
Authentic photographic documentation of our manufacturing, exothermic grounding, equipment hoisting, and multi-megawatt substation energizations.
Require Complete Substation Design, Supply & OCEI Approval?
From soil resistivity analysis and single-line schematic engineering to transformer manufacturing, utility liaison, and final inspection sign-off, SETB delivers turnkey confidence.