150-F251NBD Allen-Bradley SMC Flex Motor Controller 251A 200-460V

150-F251NBD Allen‑Bradley SMC Flex Solid‑State Controller

Key Technical Specifications

• Manufacturer: Allen‑Bradley
• Part Number: 150-F251NBD – SMC‑Flex series.
• Rated Current: 251 Amps continuous, with overload protection.
• Line Voltage: 200 to 460V AC (broader range 200–575V AC), 3‑phase, 50/60 Hz.
• Control Voltage: 120/240V AC (100–240V AC range).
• Power Output: 250 HP at 575V line connected; 350 HP at 460V delta connected.
• Enclosure: Open type – requires additional cooling and clean environment.
• Weight: 68.00 lbs (30.84 kg).
• Bulletin Number: Solid‑state controller with built‑in SCR bypass/run contactor.

Advanced Protection & Detection Features

• Electronic motor overload: Integral protection eliminates the need for separate relays.
• Ground fault detection: Programmable trip or alarm; requires an external sensor for operation.
• Programmable contacts: One normally open and one normally closed contact for flexible control.
• Soft‑start capability: Reduces excessive current and torque during motor starting.
• SCR bypass/run contactor: Built‑in to minimise heat and energy loss during run mode.

Frequently Asked Questions (FAQ)

• What is the difference between line and delta connection for the 150-F251NBD?
  In line connection the controller handles 250 HP at 575V; in delta connection it manages 350 HP at 460V because the windings reconfigure for higher power.
• Can I use this controller without an external ground‑fault sensor?
  You can enable the ground‑fault alarm or trip only when you connect an external sensor; otherwise the detection remains inactive.
• Does the 150-F251NBD include overload protection?
  Yes, it has a built‑in electronic motor overload feature, so you do not need an external overload relay.
• What control voltage does this unit require?
  It accepts 100 to 240V AC (120/240V AC nominal) for the control circuit.
• Is the unit ready to mount in a panel?
  Yes, but because it has an open enclosure, ensure proper cooling and follow the temperature guidelines (0–50 °C).
• What documentation comes with the soft starter?
  The package includes a printed quick‑start guide. For full details, download the official Allen‑Bradley SMC‑Flex user manual below.

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