Allen-Bradley 150-F251NBRB SMC Flex Smart Motor Controller 251A

Technical Specifications Breakdown

Key parameters for the 150-F251NBRB are listed below for quick reference:

Smart Motor Control for Demanding Applications

The Allen-Bradley 150-F251NBRB SMC Flex Smart Motor Controller delivers precise soft starting and stopping for three-phase AC motors. Rated at 251 A with a controller rating of 100-200 Hp @ 460V AC, this unit is built for heavy industrial environments. The 24V AC/DC control voltage simplifies integration with existing control systems. With pump control as a standard option, it reduces pressure surges and mechanical stress on piping.

Application Versatility

The pump control feature minimizes water hammer and extends equipment life. With trip classes 10, 15, 20, and 30, you can match the overload protection to the motor and load characteristics. The internal bypass contactor reduces heat dissipation during run mode, improving energy efficiency.

Installation and Setup Guidance

Mount the open-type enclosure in a clean, dry location with adequate airflow. The heatsink hockey puck thyristor modular design requires proper heat sinking. Use the provided M10 x 1.5 line/load side power terminals for secure connections. The control circuit accepts 24V AC/DC with an input ON-state current of 20mA @ 120V AC/40mA @ 240V AC. Configure the programmable NO/NC auxiliary contacts (19/20, 29/30, 31/32, 33/34) per your application needs. Set the trip current rating to 117% of motor FLC for standard overload protection.

Maintenance and Reliability

The controller features status indication (stopped, starting, stopping, at speed, alarm, fault) for easy diagnostics. The RC snubber network provides DV/DT protection for the power circuit. Metal oxide varistors (220 J optional) guard against transients. Operate within the specified temperature range (-5 to 50 °C) and humidity (5...95% noncondensing) to ensure long service life. The IP2X protection (with terminal covers) requires that covers remain installed during operation.

Compatibility and Integration

The 150-F251NBRB integrates with standard short-circuit protection devices (fuses, circuit breakers, time delay Class CC/J/L). It supports PTC thermistor motor protection with up to 6 sensors. The tachometer input (0...5V DC) enables closed-loop speed control. For braking applications, the optional SMB smart motor braking control provides adjustable braking current from 0...400% of motor full-load current.

Selection Guide and Purchasing Advice

When selecting a soft starter, verify the motor full-load current and connection type (line or delta). This model handles line connected motors up to 75 kW @ 230V AC and delta connected motors up to 400 Hp @ 575V AC. The 150-F251NBRB is available from AutoDCSTech. Please verify current lifecycle status and availability with AutoDCSTech before ordering.