June 08, 2026

A51A0327P-UM Reliance Electric Duty Master Unibrake

The A51A0327P-UM is a heavy‑duty industrial brake unit manufactured by Reliance Electric (now Rockwell Automation), designed for dynamic braking and motor stopping in industrial motion control applications. As part of the Duty Master Unibrake series, it delivers reliable, high‑torque braking for AC and DC motors in material handling, processing, and conveyor systems.

Description

A51A0327P-UM Reliance Electric Duty Master Unibrake

Product Overview

The A51A0327P-UM is a 230/460 VAC, 0.28/0.14 A dynamic brake assembly engineered to absorb and dissipate motor kinetic energy during deceleration or emergency stops. It integrates a high‑resistance braking resistor, thermal protection, and rugged enclosure for direct mounting on motor shafts or drive systems. Optimized for continuous and intermittent duty cycles, it ensures precise, consistent stopping performance in harsh industrial environments.

Key Specifications

Part Number: A51A0327P-UM
Manufacturer: Reliance Electric (Rockwell Automation)
Product Series: Duty Master Unibrake
Voltage Rating: 230 VAC / 460 VAC (dual‑voltage)
Current Rating: 0.28 A (230 V) / 0.14 A (460 V)
Torque Rating: 3 lb‑ft (4.1 N·m)
Duty Cycle: Continuous / Intermittent
Protection: Thermal overload, overvoltage, short‑circuit
Enclosure: NEMA 1 (IP20), cast aluminum
Mounting: Direct shaft‑mount or base‑mount
Operating Temperature: 0°C to +50°C (32°F to 122°F)
Weight: Approx. 3.2 kg (7 lb)
Status: Obsolete / Legacy (discontinued by OEM; available as refurbished/used)

Core Features and Benefits

Dual‑Voltage Compatibility: Operates at 230 VAC or 460 VAC, supporting global industrial motor systems and reducing inventory complexity.
High‑Torque Braking: Delivers 3 lb‑ft torque for rapid, controlled stopping of motors up to 5 HP, enhancing safety in material handling and conveyor applications.
Thermal Protection: Integrated thermal sensor prevents overheating during prolonged braking, extending service life and reducing maintenance risks.
Rugged Construction: Cast aluminum enclosure and corrosion‑resistant components withstand dust, moisture, and vibration in factory and processing environments.
Easy Installation: Compact, lightweight design with standard mounting holes enables quick retrofit or replacement of existing brake units, minimizing downtime.
Cost‑Effective Legacy Support: A reliable replacement for aging Unibrake systems, avoiding full drive or motor replacement and reducing capital expenditure.

Applications

The A51A0327P-UM is designed for industrial motor braking across sectors:

Material Handling: Overhead cranes, hoists, and conveyor systems
Manufacturing: Machine tools, extruders, and automated production lines
Pulp & Paper: Web processing and roll handling equipment
Textile: Spinning and weaving machinery
Legacy System Upgrades: Replacement for failed Unibrake units in Reliance Electric drive installations

Lifecycle and Availability

Original Production: Discontinued by Reliance Electric/Rockwell Automation; classified as legacy/obsolete.
Current Availability: Supplied by authorized distributors as professionally refurbished and tested used units.
Warranty: 12‑month warranty for refurbished units; extended options available.
Testing: Each unit undergoes electrical continuity, insulation resistance, and load testing to meet original Reliance Electric specifications。

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