Engineered LT Switchgear Architecture
The Low Tension (LT) Switchgear panel serves as the central operational nerve center of an electrical substation. Connected directly to the secondary 0.415kV terminals of the step-down distribution transformer, it regulates, monitors, and safely distributes multi-phase electric power to downstream motor control centers (MCC), sub-distribution boards (SDB), and essential building loads.
Fabricated from heavy 14/16-gauge cold-rolled sheet steel in our specialized sheet-metal workshop, every LT cubicle is compartmentalized into segregated busbar chambers, breaker compartments, cable termination alleys, and metering enclosures per IEC 61439-1/2 Form 2/3/4 standards.
Key Internal Assemblies & Specifications
Precision electrical hardware engineered for maximum uptime, thermal stability, and operator safety:
1. Air Circuit Breakers (ACB)
Installed as the primary transformer incomer and bus-coupler. Available from 800A to 6300A (3-Pole & 4-Pole) in fixed or drawout executions. Equipped with microprocessor trip units (LSIG protection: Long-time, Short-time, Instantaneous, Ground fault).
Brands: Schneider Electric, ABB, Hyundai, Fuji Electric.2. Molded Case Breakers (MCCB)
Protect outgoing feeder circuits against overload and short-circuit faults. Ratings from 10A to 1600A with thermal-magnetic or electronic trip units and high breaking capacities (36kA to 70kA Icu).
Complies with IEC 60947-2 with rotary handles & spreaders.3. Copper Busbar Architecture
Fabricated from 99.9% pure electrolytic copper flats, tin-plated to prevent oxidation. Designed at an ampacity density of 1.2 to 1.5 A/mm². Fully sleeved in heat-shrinkable Red, Yellow, Blue, and Black PVC with DMC/SMC support insulators.
Withstands electrodynamic short-circuit forces up to 65kA.The 7-Tank Hot Phosphate Anti-Corrosion Finishing Process
In Bangladesh’s humid and industrial climate, panel longevity depends on metal surface preparation. All SETB sheet metal components undergo a strict 7-stage chemical immersion bath treatment prior to electrostatic powder coating:
Routine Testing of Completed LT Switchboards
Before site delivery, completed LT assemblies undergo rigorous routine tests using calibrated instruments: Dielectric High Voltage Insulation Test (2.5kV RMS for 1 minute), Phase Sequence and Polarity Continuity Checks, Contact Resistance Measurements on Breaker Terminations, and Primary & Secondary Current Injection testing on protection CTs and relays.