Rockwell Automation announces a quantum leap in soft motor starting with the launch of two new Allen-Bradley units, the SMC-3 and SMC-Delta. The latest electronic circuitry and packaging techniques have been combined to produce class-leading soft starters that offer real three-phase control within a footprint only 45 mm wide.
Soft starters limit power line disturbances and reduce inrush currents, while reducing stress on the motor to extend operational life and minimise downtime. They are ideal for applications such as compressors, chillers, pumps, conveyors and crushers where direct-on-line starting could result in damage to mechanical systems.
Rockwell says that both new SMC soft starter units feature unparalleled functionalities in this physical size, integrating a built-in electronic overload relay as well as the thyristor by-pass contacts for all of the three phases. By reducing the number of components and amount of heat generated, panel space is kept to a minimum.
The SMC-3 is suitable for a wide range of starting applications that require the control and flexibility of a soft start, while the SMC-Delta is specifically designed as a replacement for a traditional star-delta starter. A smart and compact unit, its integrated design reduces the number of components required, optimising panel space and making installation quick and easy.
Unlike single or two-phase controllers, the SMC-3 delivers true three-phase soft starting, especially important for high inertia loads. It provides a choice of start and stop modes including soft start, which allows the motor to be raised from an adjustable initial torque value to full voltage over an adjustable ramp time from 2 to 15 seconds, and limited current start where it is possible to limit the start current to between 150% and 450% of full load current.
A selectable 'kick-start' provides a boost at the beginning of the start mode by providing current pulses of 450% of load current for up to 1,5 seconds. This allows the motor to develop additional torque for loads that are difficult to start. Stop modes include a soft stop function, for applications that require an extended coast to rest.
The SMC-3 incorporates fully programmable, microprocessor-based, electronic overload protection with adjustable trip class, motor and system diagnostics and configurable auxiliary contacts. Trip current is easily set to the motor full load current using a rotary dial and reset can be either manual or automatic. LEDs show status information including Run and Fault Diagnostics.
The overload relay is simple to set up using DIP-switches. As with all other user adjustable parameters, precise settings can be quickly set up, significantly reducing installation times. Advanced diagnostics, such as over-temperature monitor for the thyristors using internal thermistors, and protection for phase reversal, phase loss and open load, phase imbalance or shorted thyristors increase system performance by minimising downtime. Rated from 3 to 37 A (up to 18,5 kW at 400 V), the device is available in seven sizes. All are suitable for either 50 or 60 Hz operation.
The SMC-Delta is a compact, simple to use, solid state motor controller designed for 3-phase motors used in star-delta applications. It is wired for inside-the-delta configuration and features built-in electronic overload relay and thyristor bypass contacts on all three phases, allowing a smaller footprint than traditional starters.
The SMC-Delta packages the functions of power wiring, overload, timers and contactors required with a star-delta starter into a single, highly reliable, easy to set up star-delta controller. Its 45 mm width is only one third of a traditional star-delta and the competitive price makes it a suitable replacement for the conventional star-delta motor starters.
The current limiting starting method eliminates the current transition point found in star-delta applications, reducing the mechanical and electrical shock on the system. The SMC-Delta limits the maximum starting current to between 150% and 350% of full load conditions. Start times are selectable from 2 to 15 seconds. The built-in, microprocessor controlled electronic overload provides trip class selection and offers improved protection to against phase loss conditions. Trip reset is selectable to either automatic or manual. The starters are available in eight sizes to cover the range from 3 to 64 A (30 kW at 400 V), 50 or 60 Hz.
Accessories for the SMC and SMC-Delta include flexible and user configurable auxiliary contacts, MOV modules to protect against transient voltages; remote reset solenoid for large or unmanned sites and cooling fan for heavy-duty start/stop cycles. Compatible with the MCS (modular control system) range of contactors and motor protective circuit breakers, the SMC range provides outstanding performance from a compact and cost-effective package.
The new Allen-Bradley SMC-3 and SMC-Delta starters are easy to install and simple and flexible in use. Integrated features and the latest technologies provide functionality, which was not previously available within a compact 45 mm housing. They provide reliable and accurate motor protection together with advanced diagnostics, enabling the user to quickly optimise system performance.
| Tel: | +27 11 998 1000 |
| Email: | mjunius@rockwellautomation.com |
| www: | www.rockwellautomation.co.za |
| Articles: | More information and articles about Rockwell Automation |
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