Product Overview

The Allen-Bradley 150-C85NBR SMC-3 Smart Motor Controller is a solid-state motor controller designed to manage the starting and stopping of three-phase AC induction motors. Manufactured by Rockwell Automation, this controller belongs to the SMC-3 family and provides controlled motor acceleration, selectable current limiting, electronic overload protection, and diagnostic functions for industrial motor applications.

Unlike a variable frequency drive, which adjusts motor speed by changing the output frequency, the SMC-3 is primarily designed to control the motor starting and stopping process. It gradually increases the voltage applied to the motor during startup, helping reduce the high inrush current and mechanical shock commonly associated with direct-on-line starting.

The 150-C85NBR is an 85 A, open-type controller designed for three-phase power circuits. It supports line voltages up to 480 V AC and uses a 24 V AC/DC control supply. Its compact solid-state design makes it suitable for integration into industrial motor control panels and machinery.

The controller provides selectable starting times, initial torque settings, current limits, and soft-stop functionality. It also incorporates electronic motor overload protection and an integrated bypass arrangement. These features allow engineers to configure the starting behavior according to motor characteristics and application requirements.

The 150-C85NBR is commonly considered for applications involving pumps, compressors, conveyors, fans, and other industrial machinery where controlled motor starting is important. Its suitability depends on motor full-load current, starting duty, operating frequency, and the required number of starts per hour.

Technical Specifications

Note: Specifications should be checked against the nameplate and the exact product series. The supplied dimensions and weight are retained as listing information.

Function and Working Principle

The 150-C85NBR uses solid-state switching technology to control the voltage applied to a three-phase motor during startup. Instead of connecting the motor directly to full line voltage immediately, the controller gradually increases the applied voltage according to its configured starting parameters.

1. Soft Start Control

When a motor starts through a conventional direct-on-line starter, it can draw a high initial current. This sudden electrical demand may affect the power distribution system and place additional stress on mechanical components.

The SMC-3 controls the motor’s starting process by increasing the applied voltage gradually. This helps reduce the abrupt torque response associated with direct-on-line starting.

The starting time can be selected according to the application. The available settings are 2, 5, 10, 15, 20, 25, and 30 seconds.

2. Initial Torque Adjustment

Different motor-driven machines require different amounts of starting torque. A conveyor carrying material, for example, may require a different starting profile from a lightly loaded fan.

The 150-C85NBR provides selectable initial torque settings of 0%, 25%, 35%, and 65% of locked-rotor torque. These settings allow engineers to adapt the motor’s initial response to the mechanical load.

The selected value should be determined through application testing and the motor manufacturer’s recommendations.

3. Current Limiting

The controller provides selectable current-limit levels of 150%, 250%, 350%, and 450% of motor full-load current.

Current limiting helps manage the electrical demand during startup. The selected limit must be high enough to produce sufficient starting torque while remaining within the acceptable electrical and mechanical limits of the system.

An excessively low current limit can prevent a motor from accelerating properly, especially when the connected machine has a high starting load.

4. Soft Stop Function

The soft-stop function gradually reduces motor voltage during stopping. This can be useful in applications where an abrupt stop may cause hydraulic pressure changes, product movement, or mechanical shock.

For example, certain pumping systems may benefit from a controlled stopping process that helps reduce pressure transients. The effectiveness of soft stopping depends on the motor, driven load, and process characteristics.

Soft stop should not be confused with regenerative braking or precise speed control. The SMC-3 is a soft starter rather than a variable frequency drive.

5. Electronic Motor Overload Protection

The controller includes integrated electronic motor overload protection. The protection settings should be configured according to the motor’s rated current and the application’s operating duty.

Selectable trip classes allow the protection response to be matched to the expected motor starting and loading conditions. Correct configuration is essential to avoid unnecessary trips while maintaining suitable motor protection.

Role in Industrial Control Systems

The 150-C85NBR is generally installed in a motor control center or industrial electrical cabinet. It provides the controlled starting function between the three-phase power supply and the motor.

PLC Integration

A programmable logic controller can coordinate the SMC-3 with the wider machine-control system. The PLC may issue start and stop commands, monitor auxiliary status contacts, and coordinate the motor with sensors, valves, and other equipment.

The controller uses a 24 V AC/DC control supply. Its control wiring should be designed according to the manufacturer’s terminal diagrams and the requirements of the machine.

Motor Protection Coordination

The SMC-3’s integrated overload protection forms part of the motor protection arrangement. Engineers must also select suitable upstream short-circuit protection devices according to the manufacturer’s coordination tables and applicable electrical standards.

The soft starter does not eliminate the need for correctly rated fuses, circuit breakers, isolation equipment, and grounding.

Operator Interface

An HMI or control station can provide operator commands and display system status through the PLC or other suitable control arrangement.

Operators may use the control system to start or stop equipment, while maintenance personnel can use the controller’s settings and diagnostic information to investigate motor-starting problems.

Motor Control Panel Integration

The open-type design is intended for installation inside an appropriate electrical enclosure. Panel designers should consider heat dissipation, conductor routing, protective-device coordination, maintenance access, and environmental conditions.

The SMC-3 should be integrated as part of a complete motor-control assembly rather than treated as a standalone enclosed starter.

Industrial Applications

The Allen-Bradley 150-C85NBR is suitable for industrial motor applications that require controlled starting and stopping. Its 85 A rating makes it relevant to appropriately sized three-phase motors.

1. Pumping Systems

Pumps can experience pressure changes during startup and shutdown. A soft starter can gradually increase motor torque during startup and provide a controlled stopping profile where the application permits.

The SMC-3 may be used in suitable industrial water systems, process pumps, and auxiliary pumping equipment. Pump type, fluid conditions, motor current, and hydraulic requirements must be considered during selection.

2. Conveyor Equipment

Conveyor systems often experience mechanical stress when motors start abruptly, particularly when the belt carries material.

The 150-C85NBR can provide a controlled starting process that helps reduce sudden mechanical loading. The starting profile should be adjusted according to conveyor length, belt tension, load conditions, and motor characteristics.

3. Compressors

Industrial compressors may require controlled motor starting to manage electrical demand and mechanical stress. A soft starter can be used where the compressor manufacturer’s requirements permit this starting method.

Engineers should verify the compressor’s unloading arrangement, starting torque, restart frequency, and motor overload requirements before selecting the controller.

4. Industrial Fans and Blowers

Fans and blowers can have significant mechanical inertia. Gradual motor acceleration can help reduce abrupt starting torque and mechanical stress.

The controller’s current limit and starting time should be selected according to the fan’s load characteristics and the motor’s operating requirements.

5. General Manufacturing Machinery

The SMC-3 may also be used with compatible mixers, material-handling machines, auxiliary production equipment, and other three-phase motor-driven systems.

It is particularly relevant where the primary requirement is controlled motor starting rather than continuous variable-speed operation.

Installation and System Integration

Correct installation is essential for reliable operation and electrical safety.

1. Verify Motor Compatibility

Before installation, check the motor’s rated voltage, full-load current, power, frequency, and starting requirements.

The 150-C85NBR has an 85 A controller rating, but the motor’s actual full-load current must fall within the permitted application range. The manufacturer’s technical documentation provides separate current information for line-connected and inside-delta configurations.

Do not select the controller based only on the motor’s kilowatt rating.

2. Confirm the Control Supply

The 150-C85NBR uses a 24 V AC/DC control supply. Confirm that the available control power matches the controller’s requirements and that the control wiring is correctly connected.

The controller’s control circuit and power circuit have different electrical requirements. They should be wired and protected according to the installation documentation.

3. Install in a Suitable Enclosure

The controller is an open-type device and should be installed inside a suitable industrial electrical enclosure.

Allow adequate space for ventilation, wiring, inspection, and maintenance. Consider the heat generated during motor starting and the controller’s operating duty.

The supplied dimensions are 206 × 72 × 130 mm. Verify the manufacturer’s dimensional drawing before designing the mounting arrangement.

4. Configure Starting Parameters

Set the initial torque, starting time, current limit, and overload trip class according to the motor and driven equipment.

A starting time that is too short may result in excessive mechanical stress. A starting time that is too long may increase heating during acceleration. The current limit must also allow sufficient torque for the motor to accelerate under the actual load.

5. Coordinate Short-Circuit Protection

Select the upstream fuses or circuit breaker according to the manufacturer’s short-circuit protection and coordination tables.

Protection-device selection should account for the available fault current, supply voltage, controller configuration, and applicable electrical standards.

6. Commission the Motor System

After installation, verify power connections, control wiring, grounding, protective devices, and motor connections.

Test the start command, acceleration behavior, stopping behavior, overload response, and auxiliary fault indication. Record the final settings for future maintenance and troubleshooting.

Compatible System Components

The 150-C85NBR is commonly integrated with other industrial electrical and automation equipment.

The listed components are examples of equipment used in a complete installation. They are not necessarily supplied with the 150-C85NBR.

Alternative Models and Replacement Considerations

When replacing an SMC-3 controller, the electrical rating and control configuration must be checked carefully.

Before selecting a replacement, compare:

• Rated operating voltage.
• Motor full-load current.
• Three-phase power configuration.
• Control supply voltage.
• Starting duty and starts per hour.
• Selectable current-limit settings.
• Overload trip class.
• Soft-stop requirements.
• Auxiliary contact arrangement.
• Enclosure and mounting dimensions.
• Short-circuit protection coordination.

A controller with a higher current rating is not necessarily a direct replacement. The control wiring, protection settings, and mechanical installation may differ.

Key Advantages

Controlled Motor Starting

The solid-state starting method gradually increases motor voltage, helping reduce abrupt starting torque and mechanical stress.

Adjustable Starting Parameters

Selectable starting times and initial torque settings allow the controller to be configured for different motor and load characteristics.

Current-Limit Function

Selectable current limits help manage motor starting current and electrical demand.

Integrated Motor Overload Protection

The electronic overload function provides motor protection based on configured operating parameters and trip class.

Soft-Stop Capability

The soft-stop function supports controlled stopping in applications where gradual motor deceleration is beneficial.

Integrated Bypass Arrangement

The SMC-3 incorporates a bypass arrangement, helping reduce continuous heat dissipation in the power semiconductors after the motor reaches operating speed.

Industrial Automation Integration

The controller can be incorporated into PLC-based control systems through its control inputs and auxiliary status contacts.

Technical FAQs

1. What is the Allen-Bradley 150-C85NBR?

The 150-C85NBR is an SMC-3 Smart Motor Controller designed for controlled starting and stopping of three-phase AC motors. It is rated at 85 A and supports a maximum line voltage of 480 V AC.

2. Is the 150-C85NBR a variable frequency drive?

No. It is a solid-state soft starter. It controls motor acceleration and stopping but does not provide continuous variable-frequency speed control like a VFD.

3. What control voltage does this model use?

The 150-C85NBR uses a 24 V AC/DC control supply. Confirm the control wiring and supply requirements before installation.

4. What is the rated current?

The controller’s rated current is 85 A. The motor’s full-load current must be checked against the applicable manufacturer ratings and installation configuration.

5. Does the SMC-3 provide soft stopping?

Yes. The controller supports a selectable soft-stop function. Its usefulness depends on the driven equipment and the mechanical characteristics of the application.

6. Can it be connected to a PLC?

Yes. It can be incorporated into a PLC-based motor-control system. The PLC can issue control commands and monitor suitable auxiliary status contacts through correctly designed wiring.

7. What starting times are available?

The selectable starting times are 2, 5, 10, 15, 20, 25, and 30 seconds.

8. Does the controller include overload protection?

Yes. The SMC-3 includes electronic motor overload protection with selectable trip classes. The settings must be configured according to the motor’s rated current and application requirements.

9. What applications are suitable for the 150-C85NBR?

Typical applications include pumps, compressors, conveyors, fans, blowers, and other compatible three-phase motor-driven machines that benefit from controlled starting and stopping.

10. What should be checked before purchasing?

Verify the complete catalog number, nameplate ratings, control voltage, product condition, terminal condition, and included accessories. For used equipment, request clear photographs and functional test information where available.

Procurement and Maintenance Recommendations

When sourcing the Allen-Bradley 150-C85NBR, confirm the complete catalog number and compare the product label with the required motor-control specification. The 85 A rating, 480 V maximum line-voltage configuration, and 24 V AC/DC control supply are important identification points.

For replacement projects, review the motor’s full-load current, starting torque, duty cycle, and required starting frequency. Confirm that the selected controller is suitable for the intended application and that the upstream protective devices follow the manufacturer’s coordination recommendations.

For used or surplus equipment, inspect the power terminals, control terminals, housing, and visible electronic components. Check for signs of overheating, contamination, physical damage, or unauthorized modification. Request functional test information for critical installations.

During routine maintenance, inspect electrical connections, enclosure ventilation, grounding, and the surrounding cabinet environment. Review overload settings and investigate recurring trips rather than simply increasing protection thresholds.

Keep a record of the controller’s settings, motor data, wiring diagrams, and commissioning results. This information can reduce troubleshooting time and simplify future replacement work.

Conclusion

The Allen-Bradley 150-C85NBR SMC-3 Smart Motor Controller is an 85 A solid-state soft starter designed for three-phase industrial motor applications. Its 480 V AC power rating, 24 V AC/DC control supply, adjustable starting parameters, current-limiting function, electronic overload protection, and soft-stop capability make it suitable for a range of industrial motor-control systems.

As a soft starter rather than a variable frequency drive, it is intended to manage motor starting and stopping rather than provide continuous speed regulation. Correct motor selection, protection coordination, parameter configuration, and installation are essential for reliable operation.