How we arrived at ready-to-ship high voltage motors
09 March 2021
A combination of new technology, online ordering tools and global logistics network, together with an understanding of high-power applications, is changing the way high voltage motors are purchased. Rob Wood explains
The fast-paced world in which we live is demanding instant gratification, which is driving (or being driven by) instant deliveries, courtesy of Amazon (and other vendors). We are seeing this in the industrial world too. Time waits for no one, and pressure is constantly on to make and deliver motors and variable speed drives to meet demand. Now the world of high voltage motors and generators, which are traditionally custom-made and consequently have long lead times, are under pressure to arrive sooner.
Of course, there will always be applications where a high voltage motor needs to fulfil very specific requirements. For example, motors required for complex end user project specifications may require marine certification or special electrical or mechanical needs, and, as such, are classified as “engineered to order” products.
But equally, there are many applications, particularly pumps and fans, in industries like water and food and beverage, where having a reliable and efficient motor that simply keep things up and running is more than adequate. For this reason, ABB introduced its N-series range of rib-cooled motors. Together with online dimensioning and ordering, the N-series presents the easiest way yet for customers to buy pre-engineered, general purpose, high voltage machines, available from stock for immediate delivery across the UK.
The motors are pre-engineered based on the features, options and accessories that customers need most often. This means that the motors are ready and pre-packaged, so when an order is received, the engineering process is fast-tracked. This keeps production costs low and ensures a delivery far faster than previously possible.
While the N-series motors meet most general needs in their basic configuration, there are several pre-engineered options and accessories available to satisfy specific needs. All the options and accessories are pre-validated, so they can be ordered without increasing the delivery time.
High voltage motors are highly customised and purchasing can be a time-consuming process, with local sales office interaction needed to ensure the right solution is reached. However, times are changing. The latest online tool makes the motor easier to buy and streamlines the order-to-delivery process. It reduces the time needed to get a quotation and order a motor.
The online tool is called MachSize and provides a complete quotation quickly and easily. The tool can be accessed 24/7 via laptops, tablets, phones – any device that has a browser and Internet connection.
It enables the user to configure a high voltage general purpose motor, generate a quotation, send an order and obtain the necessary documentation. For instance, comprehensive documentation is ready, with pre-configured drawings and electrical performance data.
All new information entered into the tool is automatically validated. If the information affects other motor parameters, MachSize immediately updates the available options. For example, when selecting the voltage level, the tool checks which output levels are compatible with the chosen voltage. It then updates the choice of outputs displayed on screen so that only valid options are presented.
In this way MachSize continuously verifies the design and ensures that the motor being configured can be manufactured, making the quotations and technical information fully verified. The tool also checks that the configured motor meets safe starting requirements. Technical parameters and prices are regularly updated, so MachSize always shows current information. At the end of the selection process the tool provides a dimension drawing, data sheet, component list and quotation completed with terms and conditions.
So how is it possible to take, what is traditionally a highly engineered motor and create an off-the-shelf version that is cost-efficient, has short delivery times and without compromising the motors' reliability, efficiency and safety?
The latest generation of high voltage rib cooled motors is the outcome of a major engineering effort. The motor sets a benchmark for the industry, offering high power density for compact installations, packing more power per kilogram compared to conventional motors. This allows operators to often use a motor one frame size smaller than with conventional products, making optimal use of available space and suitable for retrofit applications.
Effective cooling plays a key role in achieving high power density, with rib cooling providing superior air flow for internal cooling, reducing the risk of overheating and unpredicted failures. Computational fluid dynamics (CFD) were applied to study airflows and investigate in detail the different cooling mechanisms operating inside the motor and over its external surface. As a result the cooling effects of the internal and external airflows are optimised. This means longer lifetime for bearings and longer lubrication intervals.
The innovative internal cooling system increases air circulation throughout the motor, with air routed through the channels in the stator and rotor. On the outside, the design of the outer cooling ribs (including their length, pitch and angle) is optimised to maximise the cooling surface area. The ribs are kept clear, with nothing to block the free flow of air. A new cable tray is an additional feature which helps to keep the cooling ribs clean and clear of obstacles that might disturb airflows. This tray provides a managed cable route, keeps accessory cables tidy, and contributes to consistent high quality by supporting standardised assembly.
Improved coil design
The motor’s coil design helps to increase the power density. The active parts of the coil are re-dimensioned for increased power, and more accurate forming tools ensure that the active material is used more efficiently. Overall coil quality has been further enhanced.
Rigid, weight-optimised frame
FEM (finite element method) modelling techniques are used to design the frame. This enables optimal material use while avoiding resonance, which could cause increased vibration.
Combined with a stable running temperature, this results in very reliable motor operation. The advanced frame design gives the motors improved rigidity without excess weight. Wide feet increase stability and improve accessibility, giving more space for fixing tools during installation. Oval fixing holes bring additional mounting flexibility.
Stock frame sizes range from 315 to 500 with ratings of 200 to 1,800 kW. The motors can be mounted horizontally and vertically (vertical mounting only available for 2-poles up to shaft height 355). Direct-on-line (DOL) and variable speed drive (VSD) variants are available from stock.
The fan cover can be easily removed, enabling fast access for checking the coil end and bearings with an endoscope, without removing the end shields. The flexible mounting system cuts the service time needed for repositioning the terminal box. The cable tray ensures that the cables are clearly routed and always secured in the same position, making maintenance easy. To maintain maximum performance over the entire life cycle, pre-designed fixing points enable easy mounting of condition monitoring systems. These systems collect and analyse operating data from the motors, providing early warnings of problems before failures can occur.
The motor’s rigid, weight-optimised frame is engineered to minimise vibration, and it is provided with the ABB’s latest Smart Sensor technology as standard and at no extra cost. The Smart Sensor is the next step in digitalising motor applications, turning mechanical equipment like motors, gearing, bearings and pumps into IoT-ready smart devices that can provide feedback on equipment performance, condition and efficiency.
Rob Wood is divisional manager - motors and generators at ABB
- High voltage motors and generators, which traditionally have long lead times, are under pressure to arrive sooner
- The latest online tools make motors easier to buy and streamline the order-to-delivery process, reducing lead times
- ABB's N-series rib-cooled motors are pre-engineered based on features, options and accessories that customers need most often