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What
is a PLC? Why is it better than a PC computer? Can I purchase
BatchTron for one plant and use it on another? Will BatchTron
increase speed and accuracy? Can I install BatchTron by
myself?
This page answers these
questions and others. Or ask us LIVE - see Live Chat at left.
What is a PLC? Why
is it better than a PC computer?
The PLC, or
Programmable Logic Controller, is an industrial controller that
was developed for many different automation tasks, from sequencing
traffic lights to controlling huge petrochemical plants. It
uses some of the fastest microprocessor chips, identical to those
used in many computers, but it has no rotating hard drive to wear
out, no Windows operating system and has been designed for a life
exceeding 20 years in rough, tough industrial applications.
Because it does not use Windows, it is immune to the problems you
see in your own computer from time to time. Programs that run
in your PC computer are sequential; they complete tasks in a
set order, branching along the way when they make decisions.
There are thousands of branches in a typical program and if only one
of these branches is a dead end, the program stops or "freezes".
Sounds familiar? In comparison, PLC programs run in an endless
loop like a wheel turning, repeating hundreds of times every second.
Every time around, they check all the inputs, make decisions based
on the program in the loop and set all the outputs. It is
possible for a programmer to make a mistake in the program, but no
mistake will halt the operation of the PLC; it keeps on
running. Because it cannot freeze, it performs reliably
throughout its long life, requiring little if any maintenance.
In comparison, the average PC computer is
built with commercial components that last only a few years; it
needs a controlled, cool, dry, clean environment and has little
tolerance for the dust and electrical noise caused by the motor
starters and valves found in industrial plants. The Windows
system can easily be corrupted by unskilled personnel and requires
frequent attention. BatchTron uses a PLC, making it extremely
reliable as a result. The data collecting and management
tasks, however, can be done on a PC computer in an office
environment; if the computer breaks down, the batching system
can continue unaided for as long as necessary.
BatchTron's extreme
reliability reduces your maintenance cost by a factor of 10 or
more.
Can I purchase
BatchTron for one plant and use it on another?
Sometimes yes, sometimes no. When you give
us the details for the plant, we customize the BatchTron to it.
The degree of customization depends on the plant; if it is a
simple plant like a "dry mix" ready-mix plant, the BatchTron
configuration is most likely standard and it can be used on many
other similar plants. If it is a more complex precast plant
with two or more delivery stations, the answer is inevitably "No".
We can always modify the software, however. Since BatchTron
has no hard-wired panel controls, the PLC and screen software can be
updated by modem to suit any plant configuration. If you do
this after the system has been built, however, a reprogramming
charge will apply, and the cost will reflect the complexity of the
change.
We routinely update customers' software to
accommodate plant changes and additions. For small changes this is
done via modem, but large changes can require a plant visit to start
up and train operators while making modifications to suit individual
preferences. We offer a very personal service and try to
accommodate your wishes at all times.
BatchTron is
customized, but can be changed to suit any plant.
Will BatchTron
increase speed and accuracy?
This depends
on your present batching method. If you are now using a
skilled manual operator, he can probably do better than BatchTron
when he is in top form. Manual operators tend to be erratic,
however, and they call in sick now and again. BatchTron is
consistent, giving you close to the ultimate in speed as well as the
accuracy that you require, day after day, week after week. And
your operator can get on with other things, saving you the cost of a
full-time operator.
If you already have basic automation or a PC
computer based system, BatchTron can usually increase both speed and
accuracy by an impressive factor. Systems older than 10 years
rarely have self-tuning and automatic moisture compensation, which
means that they must be regularly adjusted to achieve the best
performance. PC computers are not "real-time" systems - they
run a a speed determined by the background "overhead" processes of
Windows which varies all the time. Add to this some
maintenance problems that shut the system down from time to time and
you will see major benefits from BatchTron.
You will be
impressed by speed, accuracy and reliability of BatchTron.
Can I install
BatchTron by myself?
Of course, but
you need enough electrical knowledge to wire the plant actuators and
limit switches to the BatchTron's terminals according to the
electrical schematic. Also, the load cells on the scales must
be connected via shielded cables and the scales must be calibrated
with test weights. These steps can be done by a local scale
company while the wiring can be done by a competent plant
electrician. If you have the necessary skills at hand, you
probably don't need our help. Several customers have
self-installed BatchTrons with no problems and saved on the cost of
installation. If you find that it is too much, you can always
call us to finish the job. Most customers prefer us to be
present, however, even if they do most of the work. This is a
good safeguard against possible damage or delays and we can train
your operators at the same time.
If you have the
skills, go ahead. We'll help if you get stuck.
Can I install
BatchTron along with an existing manual control panel?
Most of the manual panel's functions are
duplicated directly from the BatchTron screen and either can be used
with no ill effects. Feed gate and scale discharge controls
can be connected in parallel to give manual backups of these
functions, which are especially useful if scale dials are retained.
Electronic scale indicators can be fitted with connectors to allow
quick change when required. The only problems occur with
dual-solenoid valve controls such as fitted on most mixer discharge
doors. These need an isolating switch to prevent both the
BatchTron and the manual control from trying to act at the same
time; this results in both the "open" and "close" valves being
open at the same time, with unpredictable results. Also, a
safety hazard results when the mixer can be started from an external
switch if it is not fitted with a physical time delay relay and
warning horn; BatchTron incorporates these functions in its
software and it is impossible to start the mixer from BatchTron
without sounding the horn, as required by OSHA and other regulatory
agencies.
Manual controls can
be used, but check the important exceptions.
How does BatchTron
compensate for moisture in the aggregates?
Moisture values can be entered from BatchTron's
moisture screen or automatically from remote sensors such as our
RadarTron
moisture sensor. The moisture in the aggregate makes up some
of its weight, causing the actual batched weight of dry aggregate to
be less than the desired target. BatchTron calculates this
error and compensates for it based on the moisture value, resulting
in new aggregate targets which are higher than the dry targets in
the formula. Likewise, the water contained in all the
aggregates is calculated and subtracted from the water target to
give a new target which is less than the formula value. The
result is better consistency from batch to batch and day to day
because every batch conforms to the theoretical mix design;
the only errors are caused by the normal batched weight variances
and, of course, errors in the moisture values entered by hand.
Accuracy
requirements of most concrete associations cannot be met without
automatic moisture compensation (from sensors) on sand and other
fine aggregates.
Aggregate moisture sensor BatchTron
I BatchTron
II
BatchTron III
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