Tuesday, January 5, 2021
Plastic Enclosure Boxes For Electrical Apparatus
Polycarbonate plastic walled in areas are for the most part more affordable than metal nooks and have amazing effect opposition. Polycarbonate is additionally unfathomably adaptable and reasonable for a wide scope of indoor and outside applications.
Due to their ease, polycarbonate fenced in areas are ordinarily utilized in work area hardware and electrical instruments related with the IT business.
HAMMOND MANUFACTURING
https://www.hammfg.com/electronics/small-case/plastic
DUINO.LK
https://www.duino.lk/Waterproof-Plastic-ABS-Enclosure
POLYCASE
Sunday, November 1, 2020
NEMA 12 Enclosures (For North American Markets)
NEMA 12 Enclosures (For North American Markets)
NEMA 12 enclosures are meant in particular for indoor commercial, manufacturing, and machining programs. These steel enclosures will defend in opposition to dust, dust, and dripping non-corrosive beverages, oil and lubricants. Our adherence to NEMA requirements will provide you with a nice enclosure for any industrial utility. We produce some of the enclosure types in aluminum, carbon steel, and stainless steel brought quickly at aggressive charges.
NEMA 12 Characteristics:
# Primarily for industrial indoor use
# Protection against dirt, falling dust, fibers, and lint
# Protection from dripping water and different noncorrosive drinks
# Resistant to harm from outside condensation of noncorrosive liquids
# Doors with oil-resistant gaskets
# Available with pre-punched holes, cutouts, raise-off hinges, insulation, latches, or locks
# NEMA Enclosures manufactures satisfactory custom and trendy NEMA-rated enclosures.
Friday, October 16, 2020
Free National Electrical Code Book 2020
Download or Read National Electrical Code Book 2020:
National Electrical Code 2020 Book PDF | Download Or Read Online (harperandharley.org)
Wednesday, October 14, 2020
PLC & DCS differences
PLC or programmable logic controlleris a robust computer used to automate processes.A DCS or distributed control system is similar to a PLC that it has robust computer controllers
However, DCS contains multiple autonomous controllers
distributed throughout the system,
It is also used to automate processes.
You may have read it and said, "So what's the difference?"
To answer this question,
we have to go back more than 40 years.
After several years in a corner design office,
this guy Dick Morley quit his job
after asking his employer to allow him to work on Saturdays instead of Fridays,
who refused.
You see, Mr. Morley loved skiing, but he found that the weekends were too crowded for his tastes.
Due to financial obligations and the like,
Mr. Morley and a friend formed Bedford Associates
where they wrote sentences,
for local tool companies, which wanted to evolve into the new stage of solid state production.
These proposals used small computers,
seemed to be repetitive in nature,
and from one project to another,
there were many similarities.
Eventually Mr. Morley got bored of writing proposals,
due to its repetitive nature,
and began to wonder if he could create an auditor who could handle these day-to-day tasks.
In fact, during his dismissal, Mr. Morley created a blueprint
for a proposed programmable controller and got it on his team.
They started designing the programmable controller.
After finding financial support,
the company, Modicon was created.
Without Modicon knowledge and during the design phase of the programmable controller,
a man from GM had presented a newspaper,
a request, for a solid state controller that will make the plants more reliable and durable,
which would also replace wired relay systems
spread to the manufacturing industry.
As the story goes, some time later,
GM is hearing about the work being done at Modicon
and final contracts with them for the purchase of over $ 1,000,000 in PLC
(then, auditors were called programmable auditors
and the "Logic" section of the current name
was not added until the dawn of personal computers or computers).
Modicon was later baptized and quickly became a business.
The name has persisted in a few acquisitions,
the latest and current is Schneider Electric.
In the beginning, the PLC was mainly used for discrete controls.
Ultimately, the big market from GM for the replacement of wired relay systems.
The programming of the PLCs was mainly in the logic of the ladder,
which is a form that looks a lot like a schematic.
The PLC received device information from the field,
solved the logic and then activated the outputs to produce the desired result.
In essence, the PLC was invented to perform repetitive tasks in a reliable and robust manner.
As for DCS, around 1975 some companies released a version of a DCS.
Basically, the creation of a DCS system was due to the increasing use of microcomputers.
There were other computer-based systems in the industry
from the late 1950s, but had limited capabilities
for scalability, durability and safety.
There were many benefits to a DCS, but one of the main draws
was that an entire factory could be connected through proprietary communications
and is controlled by a distributed system.
For example, suppose you had a plant that made an ice cream sandwich.
The factory will have a production line for ice cream
and one of the standalone inspectors would process the batch of ice cream.
After the ice cream batch is complete,
Another standalone controller can process the freezing of this ice cream.
Another controller can process the cookie batch,
while another may oversee the baking process.
With several autonomous auditors,
if one auditor failed, it would affect only this process and not all the others,
leading to a powerful system that virtually eliminated all plant failure.
DCS was really good at autonomous control of single or multiple processes.
Another important benefit of DCS was integrated monitoring
and a control system similar to current SCADA systems.
The reason it's a big benefit is that the whole label base is there,
has already been set up to control the process,
available for use on monitoring and control screens.
DCS also had operating block programming.
Program block operation, if you are not familiar with,
is a section or multiple lines of code behind a single interface.
This interface can do something like operate the manual
and automatic valve operation.
Operation block programming saves a lot of time and unnecessary programming.
In fact, the difference 40 years ago was significant
and if you had a large factory with continuous processes,
you would probably have chosen a DCS.
In today's industries, DCS and PLC are quite similar,
storage for integrated monitoring and control.
With open source communications, fiber optics,
Ethernet and the like, many PLCs can now communicate with each other
and be autonomous PLCs communicating over the network to other autonomous controllers.
This wide communication would allow the control of individual or multiple processes
from one PLC to communicate with another PLC.
See the example of an ice cream sandwich.
PLC-A could process ice cream.
When the batch is completed,
The PLC-A would communicate with the PLC-B that the process was complete
and PLC-B could then start the freezing process.
You can see it with today's technologies,
a wide and robust PLC system could do almost the same thing that DCS can do.
One advantage of DCS is the installation cost.
This advantage arises due to the position of the autonomous controller
in the process may be close to pulling large sections of I / O cables in an installation.
Another advantage is the integrated monitoring and control system.
One of the disadvantages of DCS is the lack of developers
who have some experience with a DCS.
Most flooring technicians are familiar with ladder programming
However, DCS developers and technicians
usually need more specialized experience in database operations
as well as computer-related networking knowledge.
Due to specialized training,
DCS developers are a little harder to find.
Speaking of advantages, today's PLC systems can have almost the same as DCS,
excluding supervisory control and data acquisition (SCADA).
With PLC system (multiple PLCs in factory structure),
you need to set up the monitoring and control system.
The entire DCS database would be available to set up the monitoring and system,
PLC systems individual PLC databases must be created in SCADA system software.
There are more developers available for rent in the PLC arena
and with new programming languages such as blockchain,
sequential operation, etc., the advantage of operating block programming is no longer exclusive to DCS.
This saves development time when planning a PLC.
As you can tell, there are potential advantages and disadvantages to both systems.
The subtraction is that with today's technologies,
Each system can control an entire factory.
Which system will be chosen will probably have the advantages
and disadvantages, as well as the cost of the system.
In summary, DCS has standalone controllers scattered throughout the installation.
If one controller fails, the whole factory is not necessarily affected.
It also has on-board control and control
which saves development time.
A single PLC is a single point of failure.
You certainly would not want to control an entire factory with a single PLC
however; a connected PLC system can have almost the same safety and durability as a DCS.
Thursday, July 17, 2014
Friday, June 27, 2014
Hot dip galvanizing and corrosion categories
In which corrosion categories could galvanized steel be used? This question is frequently
asked, when corrosion protection only is specified to a certain corrosion category. Such a
specification is not enough, since corrosion categories give quite wide ranges for the
environmental exposure of the steel structure without specifying corrosion protection or life
time. More information is needed as basis for a good decision.
Corrosion in different environments
Atmospheric exposure
The corrosion rate of a zinc coating is affected by the time for which it is exposed to wetness, air
pollution and contamination of the surface, but the corrosion rates are much slower than for steel and
often decrease with time. General information on the atmospheric corrosion rate for zinc is given in
ISO 9224.
Table 1 gives basic groups of environments (related to ISO 9223). Where the relative humidity is
below 60 %, the corrosion rate of iron and steel is negligible and they may not require zinc
coating, e.g. inside many buildings. When the relative humidity is higher than 60 % or where they
are exposed to wet or immersed conditions or prolonged condensation then, like most metals, iron
and steel are subject to more serious corrosion. Contaminants deposited on the surface, notably
chlorides and sulphates, accelerate the attack. Substances that deposit on the surface of the iron
and steel increase corrosion if they absorb moisture or go into solution on the surface of the iron
and steel. The temperature also influences the corrosion rate of unprotected iron and steel and
temperature fluctuations have a stronger effect than the average temperature value.
The micro-environment, i.e. the conditions prevailing around the structure, is also important because it
allows a more precise assessment of the likely conditions than study of the basic climate alone. It is
not always known at the planning stage of a project. Every effort should be made to identify it
accurately, however, because it is an important factor in the total environment against which corrosion
protection is required. An example of a micro-climate is the underside of a bridge (particularly over
water).
The corrosion of steelwork inside buildings is dependent upon the internal environment but in “normal”
atmospheres, e.g. dry and heated, it is insignificant. Steelwork in the perimeter walls of buildings is
influenced by the configuration within the perimeter wall, e.g. steelwork without direct contact with the
outer leaf of a wall comprising two parts separated by an air space is at less risk of corrosion than
steelwork in contact with or embedded in the outer leaf. Buildings containing industrial processes,
chemical environments, wet or contaminated environments should be given special consideration.
Steelwork which is partially sheltered, e.g. farm barns and aircraft hangars, should be considered as
being subject to the exterior environment.
Table 1 sets out an indication of the likely range of corrosion rates which are applicable to zinc
coatings exposed to the different types of corrosively category dealt with in ISO 9223.
Table 2 indicates the life to first maintenance for hot galvanized steel exposed to the corrosively
categories C3 to CX. For C1 and C2 hot dip galvanizing normally gives very long life times, and could
be used without further analyze.
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Tuesday, June 24, 2014
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