ABB DTC or Direct Torque Control, is the most advanced AC drive technology developed by any drive manufacturer in the world.With the revolutionary ABB DTC technology, field orientation is achieved without feedback using advanced motor theory to calculate the motor torque directly and without using modulation. The controlling variables are motor magnetising flux and motor torque. With ABB DTC, there is no modulator and no requirement for a tachometer or position encoder to feed back the speed or position of the motor shaft. ABB DTC uses the fastest digital signal processing hardware available and a more advanced mathematical understanding of how a motor works. The result is a drive with a torque response that is typically 10 times faster than any AC or DC drive. The dynamic speed accuracy of ABB DTC drives will be 8 times better than any open loop AC drives and comparable to a DC drive that is using feedback. ABB DTC produces the first universal drive with the capability to perform like either an AC or DC drive.

There are many benefits of ABB DTC technology. But most significantly, drives using ABB DTC technology have the following exceptional dynamic performance features, many of which are obtained without the need for an encoder or tachometer to monitor shaft position or speed: Torque response: How quickly the drive output can reach the specified value when a nominal 100 percent torque reference step is applied. For DTC, a typical torque response is 1 to 2 ms below 40 Hz compared to between 10-20 ms for both flux vector and DC drives fitted with an encoder. With open loop PWM drives,the response time is typically well over 100 ms. With its torque response, ABB DTC has achieved the natural limit. With the voltage and current available, response time cannot be any shorter. Even in the newer sensorless drives the torque response is hundreds of milliseconds. Accurate torque control at low frequencies, as well as full load torque at zero speed without the need for a feedback device such as an encoder or tachometer. With ABB DTC, speed can be controlled to frequencies below 0.5 Hz and still provide 100 percent torque right the way through to zero speed. Torque repeatability:How well the drive repeats its output torque with the same torque reference command. ABB DTC, without an encoder, can provide 1 to 2 percent torque repeatability of the nominal torque across the speed range. This is half that of other open-loop AC drives and equal to that of closed-loop AC and DC drives.

Motor static speed accuracy:Error between speed reference and actual value at constant load. For ABB DTC, speed accuracy is 10 percent of the motor slip, which with an 11 kW motor, equals 0.3 percent static speed accuracy. With a 110 kW motor, speed accuracy is 0.1 percent without encoder (open-loop). This satisfies the accuracy requirement or 95 percent of industrial drives applications. For the same accuracy from DC drives an encoder is needed. In contrast, with frequency controlled PWM drives, the static speed accuracy is typically between 1 to 3 percent. So the potential for customer process improvements is significantly higher with standard drives using ABB DTC technology. An ABB DTC drive using an encoder with 1024 pulses/revolution can achieve a speed accuracy of 0.01 percent. Dynamic speed accuracy:Time integral of speed deviation when a nominal (100 percent) torque speed is applied. ABB DTC open-loop dynamic speed accuracy is between 0.3 to 0.4%sec. This depends on the gain adjustment of the controller, which can be tuned to the process requirements. With other open-loop AC drives, the dynamic accuracy is eight times less and in practical terms around 3%sec.If we furnish the ABB DTC controller with an encoder, the dynamic speed accuracy will be 0.1%sec, which matches servo drive performance.

Standard applications account for 70 percent of all variable speed drives installed throughout industry. Two of the most common applications are in fans and pumps in industries like heating, ventilating and air conditioning (HVAC), water and food and drinks. In these applications, ABB DTC provides solutions to problems like harmonics and noise. For example, ABB DTC technology can provide control to the drive input line generating unit, where a conventional diode bridge is replaced with a controlled bridge. This means that harmonics can be significantly reduced with a DTC controlled input bridge. The low level current distortion with an ABB DTC controlled bridge will be less than a conventional 6-pulse or 12-pulse configuration and power factor can be as high as 0.99. For standard applications, ABB DTC drives easily withstand huge and sudden load torques caused by rapid changes in the process, without any overvoltage or overcurrent trip. Also, if there is a loss of input power for a short time, the drive must remain energised. The DC link voltage must not drop below the lowest control level of 80 percent. To ensure this, DTC has a 25 microseconds control cycle.

There are vast differences between ABB DTC and many of the sensorless drives. But the main difference is that ABB DTC provides accurate control even at low speeds and down to zero speed without encoder feedback. At low frequencies the nominal torque step can be increased in less than 1ms. This is the best available, because the motor is now the limit of performance and not the drive itself. A typical dynamic speed accuracy for a servo drive is 0.1%s. An ABB DTC drive can reach this dynamic accuracy with the optional speed feedback from a tachometer. The most striking difference is the sheer speed by which ABB DTC operates. As mentioned above, the torque response is the quickest available. To achieve a fast torque loop, ABB has utilised the latest high speed signal processing technology and spent 100 man years developing the highly advanced motor model which precisely simulates the actual motor parameters within the controller.

To learn more about ABB DTC or for ABB drive repair and replacement quotes, contact Precision Electric.

ABB Industrial Drives

ABB industrial drives are designed to tackle any motor-driven applications, in any industries, whatever the power range. ABB industrial drives are compatible with virtually all processes, automation systems, users and business requirements. The innovation behind ACS880 ABB industrial drives is architecture that simplifies operation, optimizes energy efficiency and helps maximize process output. The ACS880 ABB industrial drives consist of single drives, multidrives and drive modules.

ACS880 Multidrives

ABB ACS880 multidrives simplify industrial processes without limiting possibilities. ACS880 multidrives and ABB industrial drives can be built-to-order to meet customer needs and to meet technical challenges through a wide selection of options that are all mountable within the drive cabinet. A single supply and DC bus arrangement with multipleACS880 multidrives reduce line power, cabinet size and total investment costs. The features and options include extended I/O, fieldbus options, EMC filtering, brake options, fuses and main switch. The new cabinet design is more compact, including efficient thermal handling.Several ingress protection (IP) classes with IP22 and IP42 offering solutions for different environments are also available for ABB ACS880 multidrives. Induction motors, synchronous motors and induction servo motors are all supported as standard, without any additional software. ABB ACS880 multidrives can control motors in either open loop or closed loop, through its high precision motor control platform, direct torque control (DTC).

ACS880 Drive Modules

ABB ACS880 drive modules are designed to be built into a control cabinet by machine builders and system integrators. With inverter power up to 3200 kW, ABB drivemodules are used to build multidrive and high power single drives configurations. Everything that is required for a complete drive including rectifiers, inverters, brake options, EMC filters, du/ dt filters, I/O options, communication options and documentation is available. ABB ACS880 drivemodules are used in industries such as metals, oil and gas, mining, marine, offshore, material handling machines, pulp and paper, automotive, food and beverage, cement, power, water and wastewater.

ACS880 Single Drives

ABB ACS880-01 single drives simplify your world without limiting your possibilities. The ABB ACS880-01 is a wall-mounted single drive compatible with a wide range of applications in a broad range of industries such as oil and gas, mining, metals, chemicals, cement, power plants, material handling, pulp and paper, sawmills and marine. At the heart of the drive is direct torque control (DTC), ABBs premier motor control technology. The extensive range of options include EMC filters, encoders, resolvers and brake resistors, remote monitoring tool, as well as application-specific software. Built in safety features reduce the need for external safety components. CODESYS programming capability is embedded inside the drive for making the application run more efficiently, without a separate programmable controller. Multiple drives can be daisy-chained for synchronized drive-to-drive communication. The drive offering includes two enclosure ratings, UL Type 1 (IP21) and UL Type 12 (IP55), for dusty environments. ABB ACS880 single drives also offer built-in service features.


ACS880 ABB industrial drives can control motors in either open loop or closed loop, through their high precision motor control platform, direct torque control (DTC). ACS880 ABB industrial drives also have built-in safety features to reduce the need for external safety components. ACS880 ABB industrial drives support the CODESYS programming environment according to IEC 61131-3. ACS880 ABB industrial drives common architecture features the same control panel, parameter menu structure, universal accessories and engineering tools. The new control panel is equipped with an intuitive and high-resolution control display that enables easy navigation.

Many flexible data visualizations including bar charts, histograms and trend graphs help users to analyze processes, with assistants available to simplify setup. The menus and messages are customizable for the specific terminology of different applications. An integrated USB port allows easy connection to the Drive composer PC tool, which offers fast startup, commissioning and monitoring. The built-in energy calculators, including used and saved kWh, CO2 reduction and money saved, help the user fine tune processes to ensure optimal energy use. The energy optimizer control mode ensures the maximum torque per ampere, reducing energy drawn from the supply.

To learn more about ABB Industrial Drives, visit the ABB Website. For ABB industrial drives repair and replacement quotes, contact Precision Electric.

VFD Drives

VFD drives are known as Variable Frequency Drives. VFD drives are also known as variable speed drives (VSDs), adjustable speed drives, motor speed controllers and inverters. VFD drivesare solid state controllers used in AC or DC electric motor applications. Most VFD drives are applied on alternating current (AC) electric motors in the industrial manufacturing world. There are some direct current (DC) electric motor applications that apply variable frequency drives, but most manufacturers seek AC motors because DC motors are expensive and they’re more prone to failure. VFD drives can also be used as a phase converters when three phase motors need to be operated from single phase power.

VFDdrives areused in mills, lathes, fans, air compressors, pumps, conveyors, welders, robots and many other electric motor applications to control the speed regulation of an electric motor. Over 30 percent of the world’s electrical energy is consumed by electric motors in fixed-speed fan, pump, and air compressor applications. The basic idea for using a VFD on mills, air compressors, and fans is to decreasethe amount of electrical energy being consumed toreduce electricity costs.

Energy Savings

Only about3% of the total installed AC electric motors in the United States use VFDdrives.An estimated 60-65% of electrical energy in the United States is used to supply electric motors, and 75% of that electrical energy is consumed by fan, pump and air compressor applications.Approximately 18% of the electrical energy used in the 40 million motors in the United States could save power consumption via efficient energy improvement by using VFD drives on these electric motor applications.

Performance and Operation

VFDdrives are applied to alternating current (AC) electric motors to increase quality control and reduce energy consumption during the process of manufacturing.VFD drives increase quality control by monitoring the electric motor speed, pressure, temperature, torque, and tension; and then adjusting the motor to operate as economical as possible to meet the VFDcriteria.

Fixed-speed electric motor loads exposethe electric motor to high starting torque and electrical current surges that are up to eight times the full-load motor current. When VFDdrives are used on an electric motor, the VFDgradually ramps the electric motor up to full load operating speed; this decreases mechanical and electrical stress, which minimizes motor maintenance and motor repair costs which extends the life of the electric motor and manufacturing equipment.VFD drives haveunique programming capabilities that allow for application specific patterns to minimize electrical and mechanical stress on electric motors during operation. Every VFD drive manufacturer uses a unique parameter selection designed so that every manufacturing field has VFD products designed for their industry.

Repair and Replacement

VFD repair should be taken with extreme caution. VFD repair should only be performed by technicians who have required training and experience to work with electrical equipment. Precision Electric strongly recommends to consult an expert in the field when repairing VFD equipment.Many VFD controllers have an internal DC bus that retains a charge after power has been cut to the drive, as a result, it does not mean it’s safe to work with. Technicians working with VFD repair must always take extra precautions to ensure proper safety measures are taken, or injury or even death may occur.

Precision Electric offers free repair quotes and offers 24 hour emergency repair services. Repair services performed by Precision Electric include anin-service 12 month warranty; the Precision Electric in-service warranty begins the day repaired work is installed and put into service.

To learn more about VFD drives or for VFD repair and replacement, contact Precision Electric.