SMC Dialog Plus: Reliable Motor Control for Diverse Industrial Applications

The SMC Dialog Plus is an Allen-Bradley smart motor controller series that features innovative motor protection configurations, easy programmability, diverse networking capabilities, and the reliability of solid-state electronics. The controllers are designed to operate squirrel-cage three-phase AC induction motors rated 1 to 1000A at 200 to 600V AC or 200 to 480V AC, with 60 or 50 Hertz (Hz) AC input frequency. They are also capable of controlling resistive loads.

SMC Dialog Plus controllers are microprocessor-based and can accept 24V DC/AC or 100 to 240V AC (at 50/60 Hz) control power input, depending on the selected Catalog Number. If the selected controller supports the 100 to 200V AC control power input option, its microprocessor will self-adjust to the supplied control voltage.

Standard Features

Allen-Bradley SMC Dialog Plus controllers come with the following features as standard:

SCANport Communications

SMC Dialog Plus controllers include a built-in SCANport – a serial interface port that allows connection to a variety of optional Bulletin 1203 communication modules and Bulletin 1201 Human Interface Modules (HIMs). This port supports various industrial communication protocols, including Allen-Bradley Remote I/O (RIO), RS 422/232/485-DF1, and DeviceNet.

Power Metering

In a general context, power metering enables continuous monitoring of industrial electric motors’ operating parameters and the implementation of energy efficiency measures to meet the demanding requirements of industrial applications.

The power metering features in SMC Dialog Plus controllers take measurements and provide readouts of the following electrical parameters:

• 3-phase Voltage: This parameter measurement is unavailable during the braking operations provided by Slow Speed with Braking, SMBSmart Motor Braking, and Accu-Stop control options.
• 3-phase Current: This parameter cannot be measured during the slow speed mode and/or braking operations provided by Accu-Stop position control, the Preset Slow Speed stopping option, the Slow Speed with Braking control option, and the SMBSmart Motor Braking option.
• Power Factor: This parameter is available as a displacement power factor value, and its measurement is disabled during bypass operation.
• Motor Thermal Capacity Usage: The value of this parameter is determined by an electronic thermal overload protection system embedded in SMC Dialog Plus controllers. Measuring this parameter allows users of SMC Dialog Plus controllers to monitor the level of thermal overload capacity usage prior to the controllers’ inbuilt electronic overload circuit tripping. Overload tripping occurs when the usage value reaches 100%.
• Power usage in kilowatts (kW)
• Power usage in kilowatt-hour (kWH)
• Elapsed Time

Note: The kWH and elapsed time values are automatically saved to the built-in memory of SMC Dialog Plus controllers every 12 hours.

Also, in bypass motor configurations, SMC Dialog Plus controllers’ current sensing and power factor measurement capabilities are disabled. A Bulletin 825 power converter module is needed to maintain the kWH, kW, motor thermal capacity usage, and 3-phase current measurements.

Integrated Protective and Diagnostic features

• Electronic Motor Overload Protection: SMC Dialog Plus controllers incorporate, as standard, an electronic motor overload protection system that uses a built-in I²t overload algorithm. Along with proper short circuit protection, the thermal overload system is designed to protect the SMC Dialog Plus controller, power wiring, and connected AC induction motor against overheating from excessive overcurrent.

In addition, the inbuilt electronic overload protection system is user-programmable, offering application flexibility. For instance, users can select the overload trip class for class 30, 20, 15, or 10 thermal overload protection. The trip-current setting is programmed by inputting the rated full load current of the squirrel-cage AC motor being controlled.

The electronic overload protection system also includes a thermal memory that accurately models the operating temperature of the connected motor, thereby providing additional protection. This memory is maintained even when the input control power is disconnected. Also, ambient insensitivity is intrinsic in the design of the electronic overload protection system.

• Underload Protection: This feature enables the SMC Dialog Plus controllers to halt motor operation whenever the motor current drops below the preset underload trip level. This trip level is given as a percentage of the motor’s FLC (Full Load Current) rating and can be adjusted from 0 to 99% (where 0 is the Off setting).

The underload protection feature also provides a delay period before an underload trip occurs. The underload trip delay period can be adjusted from 0 to 99 seconds.

• Overvoltage Protection: This feature halts motor operation when an upsurge in the supplied AC line voltage is detected. The trip setting for overvoltage can be adjusted as a percentage of a given line voltage value from 0 to 99%. You can also adjust the overvoltage trip delay period from 0 to 99 seconds to eliminate nuisance overvoltage trips. Note that the line voltage should remain above the set overvoltage trip level throughout the specified delay time.

• Undervoltage Protection: The undervoltage protection feature enables the SMC Dialog Plus controllers to stop motor operation when detecting a drop in the supplied AC line voltage.

The undervoltage trip setting, given as a percentage of the specified line voltage, can be modulated from 0 to 99%. To eliminate nuisance Undervoltage trips, you can program the under-voltage trip delay period from 0 to 99 seconds, and the line voltage should be maintained below the programmed Undervoltage trip level during this period.

• Jam Detection and Stall Protection: SMC Dialog Plus controllers provide both jam detection and stall protection for improved motor and machine system protection. The jam detection feature allows users to establish the jam level as a percentage of the motor’s FLC (Full-Load Current) rating (up to 99% of the motor’s full-load rated current) and adjust the jam delay period from 0.0 to 10.0 seconds which results in application flexibility.

The stall protection feature enables users to adjust the max stall protection delay period from 0.0 to 10.0 seconds. This delay period is an addition to the preset ramp time, and it begins taking effect only after the specified start time has expired.

Energy Saver

This feature is embedded in SMC Dialog Pluscontrollers, eliminating the need for external wiring or additional panel space. It is basically used to conserve energy in industrial applications in which the AC induction motors being used are moderately loaded or unloaded for extensive durations of time. Its setup procedure is relatively easy.

With the Energy Saver activated, the SMC Dialog Pluscontroller continually monitors the load on the connected induction motor using its internal feedback network, phasing back the output voltage to the motor whenever the motor is unloaded or moderately loaded.

Phase Rebalance

This dynamic feature is integrated into all SMC Dialog Plus controllers as standard. When enabled, the SMC Dialog Plus controller continually monitors the AC line voltage being supplied and compensates for any voltage imbalance by automatically regulating the voltage output to offset the 3-phase currents being drawn by the connected AC induction motor. Successful phase rebalance extends the service life of a motor and prevents production interruptions.

Note: The Phase Rebalance feature requires that a Bulletin 825 power converter module and an Allen-Bradley 150-NFS Fanning Strip be used, and it is not active in bypass operation. Also, if you enable both the Phase Rebalance and Energy Saver, the Phase Rebalance will take precedence in operation.

Auxiliary Contacts

Each SMC Dialog Pluscontroller is equipped with three hard contacts, which is standard. The first two auxiliary contacts (Aux Contacts 1&2) are user-programmable for Up-to-Speed/Normal. They are installed at terminals 20, 19, and 18. The third auxiliary contact (Aux Contact 3) is user-programmable for Fault/Normal. It is located between terminals 30 and 29.

LCD Display

SMC Dialog Pluscontrollers feature a two-line, sixteen-character backlit Liquid Crystal Display that provides clear and informative text for parameter identification. The parameters are displayed in a systematic four-level menu structure for faster access and ease of programming. Essentially, this LCD display allows you to easily and quickly set up an SMC Dialog Pluscontroller without needing a reference manual.

Keypad Programming

Programming of operating parameters in SMC Dialog Pluscontrollers is done through a 5-button keypad located on the front side of each controller. The five buttons include Select, up and down arrows, Escape, and Enter buttons. To program a given SMC Dialog Pluscontroller, the user is required only to input the correct series of keystrokes.

Modes of Operation

Each SMC Dialog Pluscontroller includes five standard starting modes. These are:

Soft Start

In this mode, the motor being controlled is programmed at a specific initial toque value, which the user can modify from 0 to 90% of the torque of the motor’s locked rotor. From the programmed initial torque setting, the voltage output to the connected AC induction motor steadily ramps up throughout the acceleration ramp period, which is user-programmable from 0.0 to 30.0 seconds.

Suppose the controller senses that the connected squirrel-cage induction motor has achieved the up-to-speed state during the ramp operation. In that case, it will automatically switch the motor’s voltage output to full voltage. Soft Start operating mode is widely used in general-purpose motor applications.

Soft Start with Selectable Kickstart

The Kickstart feature in Soft Start mode provides a current boost at motor startup, i.e., at the inception of the ramp operation. It is designed to deliver a 550% current pulse of the motor’s full load-rated current. This enables the motor to develop extra torque to set into motion loads that demand a pulse of higher torque to start off.

Full Voltage Start

The Full Voltage Start mode of operation is intended for industrial applications that benefit from the across-the-line starting of induction motors. With this mode enabled, the output voltage to the connected induction motor reaches full voltage within ¼ second. This means that the voltage ramp time is not greater than ¼ second.

Dual Ramp Start

This mode allows users to choose between two distinct Soft Start operating profiles with independently modifiable initial torque settings and acceleration ramp periods. The initial torque settings are user-programmable from 0…90% of the torque of the locked rotor, while the acceleration ramp times are user-programmable from 0.0 to 30.0 seconds.

The Dual Ramp Start mode is beneficial in motor applications that feature fluctuating loads and, thus, irregular starting torque needs. Also, only standard SMC Dialog Pluscontrollers have this starting mode.

Current Limit Start

This mode of operation provides a determinate reduced voltage motor start. It is ideal for applications that necessitate limiting the maximum amount of starting current.  When this mode is enabled, users can adjust the current limit level from 50 to 600% of the full load-rated current. In addition, the current limit period can be adjusted from 0.0 to 30.0 seconds.

With this mode activated, if the SMC Dialog Pluscontroller discerns that the squirrel-cage motor it is operating is at the up-to-speed state, it will automatically switch the voltage output to the motor to full voltage.

Control Options

SMC Dialog Pluscontrollers are compatible with the following control options – starting & stopping options:

• Pump Control: This option helps reduce surges when starting or stopping a motor-driven centrifugal pump by steadily accelerating or decelerating the connected AC motor. The microprocessor embedded in the SMC Dialog Pluscontroller analyzes the variables of the connected induction motor and generates motor control commands that lower the possibility of surge occurrences in the system. With the pump control option, you can adjust the starting time from 0.0 to 30.0 seconds and the stopping time from 0.0 to 120.0 seconds.

• Soft Stop: This control option allows users to modulate the voltage ramp-down period from 0.0 to 60.0 seconds and is adjusted separately from the motor starting time. When the option is activated, the load on the motor will stop whenever the motor voltage decreases to a level where the load torque exceeds the specified motor torque.

The Soft Stop option is useful in motor applications requiring a prolonged coast-to-rest.  It is essentially designed for frictional motor loads that are likely to stop abruptly when the supply voltage is disconnected from the motor.

• Preset Slow Speed: The option provides a value of either 15% of the motor’s base speed (high setting) or 7% of the motor’s base speed (low setting) in the forward direction. While in the reverse direction, it can be set to either 20% of the motor’s base speed (high setting) or 10% of the motor’s base speed (low setting). It’s appropriate for positioning applications that require slow motor speed, like moving material into a precise position.

• Slow Speed with Braking Option: This stopping option allows slow speed adjustments of either 15% (high) or 7% (low) of the motor’s rated RPM speed. Its purpose is to provide a slow-speed jog for process configuration and braking-to-stop function at the end of a duty cycle. This makes it suitable for motor applications that need braking control to terminate and slow motor speed (in the forward direction) for alignment or positioning.

• SMB Smart Motor Braking: SMC Dialog Pluscontrollers feature a microprocessor-based integral braking system. This system applies a specific amount of braking current to the connected squirrel-cage AC induction motor without requiring additional hardware, such as braking contactors, speed sensors, timers, and resistors.

Thus, the SMB option allows users to adjust the braking current strength from 150% to 400% of the full load-rated current of the AC induction motor being controlled.

• Accu-Stop Control Option: This position control option merges the advantages of SMB Smart Motor Braking and Preset Slow Speed motor control options to provide coordinated position stopping. It accomplishes this by decelerating the connected motor from full speed to the specified preset slow speed setting, then holding the motor at the preset speed until a stop command is issued. After this, it provides braking torque to further decelerate the motor to zero speed.

Note: The control options listed above are mutually incompatible and should be defined when you’re ordering an SMC Dialog Pluscontroller. Also, you can upgrade your SMC Dialog Pluscontroller to another control option by replacing its existing control module.

Note: You can add only one control option to the standard SMC Dialog Pluscontroller unit.