Compact 400 Amp Automatic Transfer for 277/480V Three-Phase Systems
The RTSN400K3 is a 400 Amp Automatic Transfer Switch (ATS) engineered to provide seamless automatic power source transition between utility and generator feeds. Designed for 277/480 Volt, 3-Phase (3P) Wye systems, this switch is ideal for small to mid-sized commercial facilities, critical infrastructure, and industrial applications requiring dependable backup power for lighting, HVAC, and process equipment.
Key Specifications:
-
Amperage: 400 Amps
-
Voltage: 277/480 Volts, 3-Phase (3P), 4-Wire + Ground (Wye configuration)
-
Enclosure Type: NEMA 3R (Rainproof, sleet-resistant – suitable for outdoor installation)
-
Rating: Non-Service Rated (Requires upstream overcurrent protection; no internal main breaker)
Core Features:
-
Fully Automatic Operation: The microprocessor-based controller continuously monitors utility voltage and frequency. Upon utility failure, undervoltage, phase loss, or frequency deviation, it signals the generator to start, transfers the load to emergency power once stable, and automatically retransfers to utility when normal power is restored, followed by an adjustable engine cooldown cycle.
-
277/480V 3-Phase Wye Configuration: Supports common commercial voltage levels – 480V three-phase for motors, pumps, compressors, and heavy equipment, plus 277V single-phase for energy-efficient fluorescent and LED lighting systems.
-
NEMA 3R Outdoor Enclosure: Heavy-gauge galvanized steel cabinet with a durable powder-coated finish. Provides rainproof and sleet-resistant protection, allowing for safe outdoor pad or wall mounting without requiring an additional electrical room or shelter.
-
Non-Service Rated Design: Cost-effective and space-efficient solution for installations where overcurrent protection is already provided by an upstream main circuit breaker or fused disconnect. Contains no integral main breaker, reducing cost and footprint.
-
High Withstand Rating: Engineered to coordinate with upstream protective devices, safely withstanding available fault currents without damage when properly protected.
-
Electrically Operated / Mechanically Held: Mechanically held contacts eliminate continuous coil power draw, reduce heat buildup, and ensure positive contact retention for reliable long-term performance.
-
Digital Controller Features:
-
LED status indicators (Source 1 Available, Source 2 Available, Load on Source 1/2)
-
Push-button manual test and transfer (live or no-load test modes)
-
Programmable weekly generator exercise timer with day/time selection
-
Event logging and non-volatile fault memory
-
Adjustable voltage and frequency sensing thresholds
-
Time delays for engine start, transfer, retransfer, and cooldown (field adjustable)
Typical Applications:
-
Small to mid-sized office buildings
-
Retail centers and strip malls
-
Schools and municipal facilities
-
Water pumping and booster stations
-
Wastewater treatment plants
-
Telecommunications shelters and cell towers
-
Small manufacturing facilities
-
Agricultural and farming operations
-
Churches and community centers
