THERMAL ENGINEERING P5-6 -...

Alternator Design Edition

Edition 9

insightgenerating

Page 3-4Importance of VoC

Page 7-8Mechanical Engineering

1-12Changing the Fields

Edition 9:

THERMALENGINEERING P5-6

Contents3

7

5

9

11

Page 3Importance of VoC

Page 5Thermal Engineering

Page 7Mechanical Engineering

Page 9Changing the Fields

Page 11Systems Integration

Page 13"You Asked"

"We Listened"

Generating Insight is the Cummins Generator Technologies magazine focusing on topics relevant to our products, our customers and our industry.

Copyright 2016. Cummins Generator Technologies Ltd. All Rights Reserved.STAMFORD and AvK are registered trade marks of Cummins Generator Technologies Ltd.

Publication design by Media Mill Ltd.+44 (0) 1457 877 164

Editor: Sonia JacksonEmail: [email protected]

Editorial

1 generating insight | edition 9

Foreword

Welcome to the 9th edition of Generating Insight.

Like many companies, we appreciate the value of sharing the knowledge of our products, services and tools to build high-quality products and demonstrates that we are focused in ways to help you grow and your business succeed.

Increasingly, total product reliability and robustness are attributes which are required as customers work through cost of ownership. Cummins Generator Technologies believes that the battle is best won at the design stage, application matching and finally verifying capability.

This edition of “alternator design” has covered topics on:

■ Building an Integrated System Engineering Approach that manages all the requirements, from the Customer, from Legislation and from the Business, which then creates measurable attributes which the team have to meet with the product design and validated through robust and reliable, design verification plans and reports

■ Managing the Physics of the Machine, Thermal, Electromagnetic Electrical and Mechanical in a Multi-Physics based approach, using connected analytical tools to create optimized product design.

■ Creation of a long term product and technology plans that are connected in an Integrated Product Plan that is delivered through our robust Value Package Introduction projects. These projects have a clearly defined set of deliverables aligned to product and business timing versus launch expectations. Each new project has a pre definition phase that outlines the scope and technologies as well as building prototypes to understand what can be achieved is realistic within the program phase.

We strive for excellence in delivery of world class products and services that set STAMFORD and AvK branded products apart in the market place.

We thank you for your continued business and wish you a productive and successful 2017.

Kevan Simon Chief Technical Director

2generating insight | edition 9

No one becomes an industry leader without listening to the customer. Customers drive our business, and paying attention to their requirements, is what sets us apart.

We use the Voice of the Customer (VoC) technique to conduct market research in order to identify customer needs and wants.

With our new STAMFORD S-range launching into the market, it is important to highlight how we ensure our products align with our Customers’ needs.

Cummins Generator Technologies has a three-stage process on how to analyse the customers’ voices and translate them into tangible features in our alternators. The process is illustrated in the figure below:

The first step revolves around approaching our Customers and conducting interviews, mainly focusing on what they currently like about our products, and what features they would like to see as part of the new product development.

The voices collected are then used as an input to the “Value Package Profile” (VPP), where the voices are translated to the “alternator language”. For example, one voice could be:

“I want to be able to easily access the diodes during service regimes”

This is then translated into “Serviceability”, the alternator needs to be optimised to allow quick and easy access

Importance of

VoCCONDUCT

VoC INTERVIEWS

CREATE THE VPP

CREATE THE TECHNICAL

PROFILE

CONDUCTVoC

INTERVIEWS

by Andrea Naseem


to key components. Another aspect of the VPP, is market research, benchmarking our products against the competitors, and identifying further opportunities to gain market share.

Having created and validated our VPP, the next step involves creating the Technical Profile. Here, the VPP is used as the revolving axis for our engineers to base their design decisions for the new product. Following the “Serviceability” example, the Technical Profile further translates this term into; “Optimise the Non Drive-End bracket”.

With our VoC process we ensure that the Customer is the epitome of our new product designs, which justifies our motto:

YOU ASKED.WE LISTENED.

CREATE THE VPP

CREATE THE TECHNICAL

PROFILE


by Darren Camilleri

and Joseph Borg

The thermal engineering team provides technical expertise and innovative tools for improving the thermal performance of our electrical machines.

We work with global design teams to support new product introductions, current products as well as our customer engineering team. The main challenge we face, is to do our job without negatively affecting the machine’s electrical or mechanical performance. In doing so, we come up against a number of limiting factors; such as temperature class limits (NEMA & IEC) and efficiency targets.

To give an idea; a 10°C rise over the standard temperature will halve the machine’s life and reduce the machine’s efficiency by 2%.

So, what is ‘thermal performance’? It refers to the machine’s self-cooling capability and the temperatures it reaches as a result. Cooling is achieved by a fan that is driven by the alternator shaft which induces an airflow through the machine. This airflow then splits between the rotor & stator as shown in Figure 1.

Fan

OutletFigure 1: Airflow Schematic of a Synchronous Generator


Airflow and temperature are directly related; as the former goes up, the latter drops. So the bulk of our work focuses on designing innovative ways of optimising this airflow.The simplest way of doing this is to increase the overall airflow. We have designed the new, more aerodynamic drive-end adapter, which has given us upto 10% increase through CoreCooling™ technology. This resulted in a 12°C drop in machine temperature.

Another way of optimising the airflow is to re-distribute it to hotter areas of the machine. We’ve worked cross-functionally to add extra cooling channels at the centre of the machine. This introduces cooling air at the machine’s hotspot, giving maximum benefit.

In order to validate these technologies, we use the test facilities at our Stamford plant along with thermal modelling tools like Computational Fluid Dynamics (CFD). (Figure 2).

As cost, power density and efficiency requirements become more stringent, the thermal engineering function plays an increasingly important role in ensuring we give our customers the best possible product.

Rotor

Stator

Inlet

Figure 2: Streamlines in CFD showing airflow in the CoreCool™ DE adapter

THERMAL PERFORMANCE REFERS TO THE MACHINE’S SELF-COOLING CAPABILITY AND THE TEMPERATURES IT REACHES AS A RESULT


MechanicalENGINEERING

Mechanical Engineering is a diverse function which ranges across all aspects of engineering such as design, manufacture, validation, failure investigation etc. It is applied to almost everything, from the smallest parts (nuts, bolts etc.) up to complex systems (alternators, engines, gensets etc.).

Our mechanical engineering team is committed to innovative design work, in depth multi-physics analyses, comprehensive testing and validation programmes and continual engineering support of product manufacture and release throughout the product’s life cycle. The goal of the mechanical engineering team is to ensure that the alternator maintains its structural integrity whilst producing its designed electrical outputs. The power industry is always seeking to improve a machine’s power to weight ratio but this is, however, not as straightforward as it sounds. The more power an alternator is made to produce, the more its structural stability is affected.

For example:-

One way of increasing an alternator’s performance is to put more copper on the rotor. From a mechanical point of view this increases the stress in the rotor laminations, but it could also have an effect upon the thermal behaviour of the machine, which in turn may lead to variations in material properties and life expectancy. See Figure 1.

In this instance the mechanical engineering team would work very closely with the electrical and thermal engineering teams, when evaluating any design changes such as this.


by Abhinav Patrick Tobin

MechanicalENGINEERING

ONE WAY OF INCREASING AN ALTERNATOR’S PERFORMANCE IS TO PUT MORE COPPER ON THE ROTOR

With advancements in modern technology, Cummins Generator Technologies promotes and encourages the use of software based analysis led design, however, the company still uses fundamental analysis in the form of hand calculations and validation through physical testing and experimentation. At Cummins Generator Technologies, calculations involving: - Dynamic Behaviour: Complex Stress and Strain: Thermal Differentials etc. are all performed by Cummins Generator Technologies mechanical engineers.

Cummins Generator Technologies’s Mechanical Engineers are trained to use numerous design and analysis software tools such as CREO, ANSYS, ROMAX etc. which all aid in the design and analysis process.

■ CREO is a 3D modelling software package that is used to assist in the design and draughting processes. It can be used for primary design work or for making modifications to alternator components, all of which can be imported into the ANSYS software package (or any other compatible analysis software package) for analysis. CREO is also used to provide customers with 3D models of complete alternators, for the purpose of genset design and analysis. See Figure 2.

■ ANSYS is a finite element analysis software package that analyses the effects of applying: - loads, displacements, velocities, accelerations, constraints, thermal energies, mass, inertia, stiffness etc. to the modelled components. Cummins Generator Technologies' Mechanical Engineers use ANSYS to evaluate the capability of designs to meet all required internal and external design and application performance specifications. See Figure 3.

Whether it be Electrical, Mechanical or Thermal Engineering, the collaborative aim of engineers at Cummins Generator Technologies is to provide their customers with products that meet all of their current and future needs and expectations.

Figure 1. Rotor core with ‘red’ arrows indicating forces due to copper and the wedge as a result of rotation. The transparent circles indicate areas of high stress due to the forces.

Figure 2. CREO model of an HC4 alternator.

Figure 3. Result of a rotational force applied on an HC5 Frame.

Rotor Pole High Stress

Wedges

CopperWindings

Shaft

RotorLamination


Electromagnetic design is right at the core of the product design stage in alternators and can mean the difference between releasing a good product and a great product. The expertise we have at Cummins Generator Technologies allows us to tip the scales into consistently releasing great products which either meet or exceed our customers’ demands and requirements in relation to, for example, size and performance.

We at Cummins Generator Technologies not only perform extensive computer simulations and validation processes to guarantee our generator quality, but continue to improve our alternators with various optimisations of the electromagnetic design through a computer simulation method called Finite Element Analysis (FEA), to ensure our products are the of the highest quality and best performing in the market. (Figure 1).

BEING ABLE TO USEMULTI-PHYSICS SOFTWARE ALLOWS A MORE COMPLETE OBSERVATION

by Anthony Spargo


Changing the Fields:An Electromagnetic Design Perspective

Figure 2. Electrical machine in finite element analysis software displaying magnetic flux density.

Figure 1. Electrical machine in finite element analysis software with “mesh” applied.

FEA is an expert tool to perform a multitude of analyses on alternators and is used from the principle stages of design, all the way to finishing touches to bring out that extra few percent of performance. The electromagnetic FEA software specialises in looking into the electrical side of the design and allows us to create a very wide range of tests, for example the losses in the stator iron of the machine. (Figure 2).

Our efforts are not however solely focused on using FEA, we also use a few other tools which have varying degrees of ability. One of those other tools was developed in house and is instantaneous at producing results rather than consuming a number of hours to yield a result. However this tool is much more limited and understandably less accurate than the FEA software. This fast tool was built based on classical theory and the magnetic reluctance circuit, so naturally there are no massively iterative, time consuming, calculations to be performed here.

The next piece of software we have at our disposal is a step up from the prior but still not as good as our FEA methods. This tool uses design templates which are modifiable by inputting the various machine dimensions, again this is based on the magnetic reluctance circuit theory but this time within a more in depth software package that allows for a much broader analysis more akin to that capable in our FEA software. It is slower than our

instant results tool but generally more accurate and still a lot faster than finite element analysis.

Another option is multi-physics software which performs' beyond the scope of our electromagnetic FEA software and allows for the inspection of other performances such as mechanical stresses and temperature in various places inside the generator along with continuing to be able to simulate the electromagnetic fields inside the machine at the same time. Being able to use multi-physics software allows a more complete observation of how small changes and optimisations for the electromagnetics affect the rest of the generator and so can help ensure the excellence of our machine design.

When designing a generator from an electromagnetics point of view, there is much more to consider than simply the size and how much power we want to get out of the machine. Not only do we have a number of steps from hand calculations to computationally heavy finite element analysis, but there is a multitude of different ways in which we can alter the geometry inside the rotor and stator to manipulate the magnetic field in order to, for example, reduce the percentage of total harmonic distortion in the output voltage at the terminals, and also to improve the electrical efficiency; both of which when kept to a high standard contribute to a higher quality machine.


Our business is committed to an integrated product design plan. If the inputs are not clear, and you don’t know where the target is, how will you know when you have hit your objectives? This might sound obvious, as this question normally is addressed at the beginning of any piece of work. Interestingly, if you put a group of experts in a room together they are fantastic at creating solutions, before agreeing the definition. However, all too often when all is done, if we ask was the problem statement correct, and did we deliver something the customer wanted, we might have a surprise. As illustrated, disconnects between customer and creator can have unexpected outcomes.

Systems Integration involves meeting customer needs with a design and joined up development plan, whilst avoiding flaws. Flaws which come from:

■ Human factors

■ Design deficiencies

■ Materials failures

■ Environments conditions

So how do we create a utopian environment which delights our stakeholders? The starting point for any activity needs to be a clear problem definition from the customer to determining requirements and challenges. Cummins Generator Technologies is actively cataloguing its application base to understand what customers actually require, and is using this intelligence as a design input.

This means we can service customer expectations or improve our product launches by integrating our people/functions from the beginning. This provides two layer of focus:

■ Design a product which recognizes all interfaces with the customer, targeting innovative solutions.

■ Bring all Cummins Generator Technologies functions together to ensure the end experience is targeted (Marketing through to Customer Support).

■ Example: The generation of electricity is the fulfilment of the challenges of a hierarchy of requirements through a systematic approach.

Systems integration starts by defining a clear direction as described. It is important to communicate these requirements in an unambiguous way to everyone. The tools we use for this are:

■ Application Attributes – external requirements

■ Technical Scope – all requirements

A SYSTEMS INTEGRATIONApproach toProduct Development by Phil Bend


Process

DefineProblem

Innovate

Customer

Concept

ApplyIntelligence

Solution

LibraryManagement

Attributes Model(External

Requirements)

KARM Model(Internal

Requirements)

Voice of Customer Technical Profile Concept Development Test Plan (DVP & R)

System

Sub-system

Closed Loop Process

To make this occur, the information is locked down and stored in a common database base for all to use.

Having created a project scope that is both specific and measurable, it is important to test the validity of this data. Cummins Generator Technologies have a suite of tools that allow programme teams to:

■ Qualify the inputs and outputs, seen at all levels of the product.

■ Understand what its function is.

■ Provide an awareness if external factors or potential error states cause deviations to the desired result.

■ A detailed assessment of each potential failure associated with the requirements

Even if you don’t work in Engineering, Systems Integration applies to you. Every business function plays a part in delivering a debugged solution.

Having understood the function and the application/environment where our product will be placed, we can now close the functional loops, proving Cummins Generator Technologies has a financially sustainable product. At a high level this involves looking at the risks the process unearths, making sure proof of understand is unequivocally provided.

At a departmental level, within the VPI process, this means different things:

■ Customer Engineering: Application attributes have been answered by Marketing’s VPP

■ Engineering: Technical Profile – validation & verification defined

■ Manufacturing: Quality control and assurance process complete

■ Purchase: Supply base model delivers the requirements

■ Finance: 10 year plan able to show the value to the business.

A fully integrated system ensures Cummins Generator Technologies’s products will meet the customer’s acceptance requirements as the process continually reviews the initial requirements i.e. customer focused. If for some reason the customer asks for something that is not achievable, an alternative can be agreed upon as part of initial contract discussions.

There are many other benefits from this type of approach. Spin-offs from this process include a library of intelligence and improved efficiency/time to market.

Progress report:Whilst there is nothing new, an integrated systems approach is being rolled out with all VPI projects.

The projects involved so far include:

All new product developments.

In summary, our aim in the words of a Cummins Generator Technologies leader is to:

"Become the best students of the customers and markets we serve & applying it ...."


SYSTEMS INTEGRATION INVOLVES MEETING CUSTOMER NEEDS WITH A DESIGN AND JOINED UP DEVELOPMENT PLAN

by Anita Fountain

Enhanced thermal management

High efficiency air-flow

Optimised power density core

New core length, 450kVA

Adaptor foot option, enabling switching between alternative brands

OUR DIFFERENCE? THE DETAIL.

Product evolution through technological revolution. Our new CoreCooling™ technology results in improved thermal performance and increased power density... it’s in the detail.

To find out more visit stamford-avk.com

Flexible foot option, enabling switching between S4 & S5

The NewFitted with CoreCooling™ technology

Come and

learn more about

the New cccccccc

S range - visit us at

Power-Gen

Orlando, USA.

13th-15th December, 2016

Stand No.2222

15676 S4 advert 8 x 10.5.indd 1 10/11/16 10:00 AM

Has been a successful campaign of introducing the new range of STAMFORD S0/S1 products.

The new range of STAMFORD® alternators targeted at the 7.5 to 62.5 kVA power range was launched at the Middle East Electricity 2016, allowing Cummins Generator Technologies to bring to market the most compact and lightweight industrial alternators of its kind, primarily aimed at the global standby market.

The new products, which have been designed for enhanced usability, draws on the company’s 100 years’ of experience, developing and manufacturing high performance and efficient power generation technology. The new cost effective range delivers proven reliability of over 20,000 hours. Cummins Generator Technologies has worked in partnership with customers to develop the new user-friendly range of alternators, which have been designed to enable easier coupling, reducing generator-set assembly time by around 20%.

Welland Power, a long term customer, based in Spalding, Lincolnshire is the first to purchase the new range, with an order of 300 units, worth over £150k, takes it up to 2352 in total across the STAMFORD range so far this year.

Welland Power products are built and designed in a modern UK factory, ensuring that the products are of the highest quality. The base frame, canopy are silencers

are all manufactured and fabricated on site. Additional investments in laser fabrication equipment, automated material processing and precision CNC material forming equipment has increased repeatability, improved product aesthetics and allowed the processing of higher material grades to further improve durability, functionality to deliver customer satisfaction.

Charlie Farrow, Managing Director said “The new STAMFORD S0/S1 product is a step forward for OEM’s in the low kVA power nodes. Combining a new robust design with proven technology to provide a manufacturing solution that enables faster assembly for the OEM and high quality power for the end user. A range of options that covers the requirements of the industrial market also means the S0/S1 can be used in almost any industrial application. We believe that the S0/S1 is a giant step forward for STAMFORD in modernizing its range and that this product will significantly increase the market share over the coming years.”

WELLAND POWER PRODUCTS ARE BUILT AND DESIGNED IN A MODERN UK FACTORY, ENSURING THAT THE PRODUCTS ARE OF THE HIGHEST QUALITY.

YOU ASKED.WE LISTENED.

Michael McWilliams, Sales Manager presenting Managing Director Charlie Farrow with his recognition gift of the first order of the new range.

STAMFORD S0


Enhanced thermal management

High efficiency air-flow

Optimised power density core

New core length, 450kVA

Adaptor foot option, enabling switching between alternative brands

OUR DIFFERENCE? THE DETAIL.

Product evolution through technological revolution. Our new CoreCooling™ technology results in improved thermal performance and increased power density... it’s in the detail.

To find out more visit stamford-avk.com

Flexible foot option, enabling switching between S4 & S5

The NewFitted with CoreCooling™ technology

Come and

learn more about

the New cccccccc

S range - visit us at

Power-Gen

Orlando, USA.

13th-15th December, 2016

Stand No.2222

15676 S4 advert 8 x 10.5.indd 1 10/11/16 10:00 AM


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Copyright 2016, Cummins Generator Technologies Ltd. All rights reserved. Cummins and the Cummins logo are registered trade marks of Cummins Inc.STAMFORD, AvK and MARKON are registered trade marks of Cummins Generator Technologies Ltd.

Part No. MG_GI_P_EN_AF Rev. 01

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