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L&T (Larsen & Toubro) FN-250 TPN

The L&T FN-250 TPN is a heavy-duty 250A switch disconnector engineered for high-demand industrial environments requiring absolute 3-phase and neutral isolation. As a flagship of the FN series, it is purpose-built for AC-23A utilization, making it exceptionally capable of handling highly inductive motor loads and frequent switching. With a robust 25kA breaking capacity and a rotary operation mechanism, it provides a safe, manual disconnection point for 415V power circuits, ensuring reliability where downtime is not an option.

Quick Answer

The FN-250 TPN is best used as a main incoming isolator or sub-panel switch for industrial machinery, large-scale HVAC systems, and commercial distribution boards requiring 250A 4-pole isolation under AC-23A load conditions.

✓250A High-Current Rating designed for heavy-duty industrial power distribution systems.
✓TPN (Triple Pole & Neutral) Configuration ensures simultaneous isolation of all phases and neutral.
✓AC-23A Utilization Category certified for switching highly inductive motor loads and mixed loads.
✓25kA Short-Circuit Breaking Capacity provides superior resilience against electrical faults.
✓Compact Thermoplastic Housing with IP40 protection, optimized for panel and DIN rail mounting.

Choose the L&T FN-250 TPN if your application demands a time-tested, high-capacity (250A) isolator that can safely switch inductive motor loads in a 4-pole configuration without the high cost of automated circuit breakers.

✓ Who Should Buy

  • •Industrial panel manufacturers needing a reliable 250A main isolation switch.
  • •Commercial facility managers maintaining large-scale HVAC and pump control centers.
  • •Electrical contractors sourcing high-durability switchgear for Indian industrial projects.

✕ Who Should Avoid

  • •Residential users with simple single-phase or low-current (under 63A) requirements.
  • •Applications requiring integrated automatic overcurrent or short-circuit protection (MCCB required instead).
Product Overview
The L&T FN-250 TPN represents the gold standard in Indian industrial switchgear, having maintained its market relevance since its 2008 series launch. This 4-pole disconnector is housed in high-grade, flame-retardant thermoplastic, offering a durable solution for 415V electrical architectures. Its rotary handle mechanism provides clear tactile feedback and visible indication of the switch status, which is critical for maintenance safety protocols in factory environments. Designed for flexibility, the FN-250 supports both panel mounting and DIN rail installation, allowing it to fit into varied switchboard designs. While it functions primarily as an isolator without internal trip units, its ability to withstand significant electrical stress makes it the ideal partner for upstream protection devices. With its 1-year warranty and compliance with rigorous safety standards, it remains a trusted choice for electrical contractors across India.

BrandL&T (Larsen & Toubro)
Model NameFN-250 TPN
TypeMain Switch Disconnector
SeriesFN Series
Housing MaterialThermoplastic
Country Of OriginIndia
Release Year2008

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Engineering Analysis
From an engineering perspective, the FN-250 TPN utilizes a quadruple-pole synchronized switching architecture. Unlike basic 3-pole switches, the TPN version ensures the neutral path is disconnected alongside the phases, preventing potential circulating currents during maintenance. The AC-23A rating is the standout technical feature, signifying the switch's capability to break stalled motor currents (typically 8-10x rated current) without contact welding, a common failure point in lower-rated disconnectors. The IP40 rating ensures the internal mechanism is shielded from solid objects greater than 1mm, suitable for clean-room or standard industrial panel enclosures.

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