The watchword is 'simplicity'
Why is the world demanding drives that are simple to commission? James
Haigh investigates the push from customers to make drives simple to use
and easy to install.
What do drives users want? In a survey of 279 US readers, the trade
magazine Control Engineering asked what features were most desired in ac
drives. Sixty-three percent responded simple controls and set-ups; 45%
said convenient operator interface; while 45% mentioned programmability
and 37% were concerned about pricing.
For the past five years, most surveys into what customers want from their
drives invariably show these as the four most desired features. And,
during this period, manufacturers have been eager to oblige, by designing
drives, keypads and control panels that offer some very clever and
innovative ways to make life easier. Yet, even today - five years on -
the surveys still show easy set-up, ease of commissioning and ease of use
as the leading demands of today's customers. So are customers
disillusioned with what they are being offered? Are the manufacturers
truly hitting the mark?
User interface
Manufacturers have taken the desire for easy-to-use drives to heart and
have approached the challenge in three ways. Firstly, the user interface
itself has been closely scrutinised. Today, drive set-ups can be
performed quickly using detachable and/or interchangeable keypad
interface modules. Most keypad modules can be removed, whether the drive
is powered or not. Most companies offer keypads that can be mounted on
the drive, as well as used as handheld devices.
Keypad modules allow users to programme speed, start, stop, acceleration,
deceleration and parameters into the drive. Some modules permit uploads
and downloads so that multiple drives requiring the same set-up
parameters can be programmed using only one keypad. The parameters for
one drive are set with the keypad, and then those parameters are copied
into the keypad, which is taken to other drives for subsequent set-ups.
The user then downloads the set-up parameters from the keypad into each
drive in succession.
These devices normally feature backlit liquid crystal display (LCD)
readouts. The readouts show speed information, set-up parameters, or
error codes.
Secondly, manufacturers have been looking at the best way for the user to
interface with the keypad and this has resulted in an array of push
buttons, potentiometers, knobs and digital scroll dials.
But perhaps the hardest thing to achieve has been improving the quality
of the actual data that is presented to the user and simplifying the
format of what is displayed.
The real challenge is with drives used for demanding applications. It is
these drives that have complex parameter set-ups and routines that so
often need user-manual intervention. And it is in this area that
manufacturers are now turning their attentions, driven by three specific
customer needs: time saving in installation and commissioning; longer
uptime, and reduced scope for errors.
Drives are becoming mature products. In the early days, greater attention
was given to getting the power electronics right and making sure the
drive could do what it was basically intended for - control motor speed
and save energy. As the product matures, then greater emphasis is placed
on giving more functionality but in a user-friendly way. With PCs this
was through Windows and the mouse. And so it is with drives and their
intelligent keypads and self-diagnostics.
Intelligent drives
Many drive manufacturers offer software that monitors, diagnoses,
configures, and archives information and parameters concerning drives in
the plant. This feature is useful for plant engineers with many drives to
maintain. Set-ups are done within the software, and then downloaded to
the appropriate drives. Drive set-up information is archived for future
retrieval. But still this information needs the intervention of
user-manuals in order to get the full benefit.
Manufacturers are now striving towards developing intelligent control
panels that remarkably decrease the need for paper-based manuals. The
benefit is significant time saving in both installation and
commissioning. As the keypad uses plain language phrases, which guide the
user, the training needed to be able to start-up the drive is
significantly reduced.
Most investments decisions today carry a proviso for fast installation to
ensure production starts rapidly and without hassle. The key lies in the
speed at which a machine can be got up and running again. If a machine
breaks down, the cost can be as high as £10,000 per hour. Easy set-up and
commissioning is then a priority. Such urgency increases the risk of
errors in installing and commissioning. These can be overcome by
eliminating manual intervention wherever possible and it is the keypad
that holds the key to reduced errors.
New customers
There is also the emergence of another customer type. Some OEMs and light
industry are seeing the benefits of using ac drives to customise drive
functions for specific applications quickly and cost-effectively. In many
cases, these companies have never employed automation or electrical
professionals. Yet they are also under continuous pressure to reduce cost
and improve productivity, and so end-users and OEMs across a wide range
of industries have adopted ac drive technology for use in their motion
control applications.
It's all about total cost of ownership including commissioning, swap-outs
and maintenance. Users of ac drives can now reduce costs even more by
employing application-specific drive solutions that are available from
selected suppliers. These drives incorporate incremental functionality
that supports specific applications such as fan and pump control, mixers,
or crane controls. They can improve total cost of ownership through
reduced start-up times, lower integration costs, and improved machine
productivity.
Very often, this customer group does not know what an algorithm or vector
control is. Even the wholesalers, from which they may purchase these
drives, do not have the basic drives training. Here the need to get
drives up and running even quicker is vitally important if this market is
to be tapped into. The market is big and so that is a pretty good
incentive to make life easier for these users.
The onus is clearly on the manufacturers to continue making life easier
for their customers. If current trends are anything to go by, drives
should be much easier to commission in the future. But the journey
towards the genuine 'plug-and-play' drive has only just begun.
The drive that talks back
One initiative by ABB in its effort to make drives more easy to set up
and install is a development called Start-up Assistant. It is basically a
keypad that asks questions and guides the user through both start-up and
commissioning using plain language text, rather than complex parameter
numbers and codes. When the drive is first switched on it recognises
whether or not it has been commissioned before and if not, it prompts:
'press function to start the start-up assistant'. From here, the
assistant asks the user a step by step set of logical questions, which
help with the set-up of language, motor control, option modules and so
on. All along the way the user can gain plenty of help from plain text
help screens, relevant to the task being performed. The new ACS 800
platform from ABB has such an intelligent control panel.
James Haigh is general manager, drives products at ABB