What is 4-20 ma?

This article will be geared towards the curious, I am not going to try to train you how to work with the subject materiel.
But you will be able to converse intelligently after reading this.

BASIC DEFINITION

4-20ma can be either an input or output from the perspective of a PLC, (Programmable Logic Controller)which was covered in an earlier article.
The PLC specialty cards necessary are referred to as Analog cards(both input and output types).

MA stands for milliamp, a measurement of current flow. 4-20 is the lower and upper limits of this defined scale.
One example is the use of this scale to order a motor to run at a specific speed, with 4ma representing stopped and 20ma representing full speed.

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The Joy Of Victorious Troubleshooting

Usually In a manufacturing facility you will find several mechanics and only 1 or 2 electrical people at any given time.
This is because you are dealing with moving equipment, which breaks and wears out frequently.
For the electrical people there are plenty of preventative maintenance tasks and upgrades to do.

However sometimes the equipment refuses to work or does something erratic, and no one knows why. Continue reading “The Joy Of Victorious Troubleshooting”

Concerning Electrical Enclosures

An electrical enclosure is a container for electrical or electronic equipment.
They sometimes are also used to mount knobs, switches, and other user controls plus indicators such as touchscreens, readouts and various other displays.
Their primary function, however, is to protect users from electric shock and protect the internal components from the elements.
Regulations may dictate the features and performance of enclosures for electrical equipment in hazardous areas, such as coal mines, petrochemical plants, and various power distribution facilities. Electronic packaging may place many demands on an enclosure for: Continue reading “Concerning Electrical Enclosures”

A little about PLC’s

It seems to me that most information available on this topic assumes a moderate knowledge level before beginning their discussion, so I intend to break this down a little to accommodate those of you who may not have even heard of PLC’s before today.  Along the way, I will share my perspective as someone who has been working “hands-on” since the late eighties.
The most basic form of PLC’s are hardened, industrialized PC’s which provide inputs and outputs. Continue reading “A little about PLC’s”

About Lockout-Tagout…

Lockout-Tagout is a reference to established safety procedures for use in industrial and research facilities.
Lockout-Tagout was first created and introduced by OSHA in 1982 in response to the high number of workers suffering injury and death in those facilities, OSHA (Occupational Safety And Health Administration) itself is a federal agency of the United States and was established in 1971.
The regulations went into effect in 1989, and are directly responsible for a dramatic decrease in the number of injuries and deaths in the US workplace.
Lockout-Tagout procedures ensure that dangerous machines have been properly shut-down and are not capable of being re-started before the completion of maintenance or servicing work. They require that all hazardous energy sources have been: Continue reading “About Lockout-Tagout…”

About Motor troubleshooting and the use of Meggers…

This particular activity is potentially very dangerous because power needs to be applied and locked out frequently, so please follow proper lockout-tagout procedures!
Meggers are a must in the area of industrial electrical troubleshooting because they can help quickly identify some sources of malfunctions while eliminating other sources as the cause of the malfunction.
As an example, let’s say that a motor refuses to turn. The problem could be coming from let’s say 3 different directions. Continue reading “About Motor troubleshooting and the use of Meggers…”

Typical Maintenance Buyer Description And Duties

Buyer

Usually reports to and is supervised by the Purchasing Manager

Major Responsibilities:  It is the responsibility of the Buyer to work with a minimum of direction or supervision to accomplish all of the duties delegated by the Purchasing Manager. A Buyer has the responsibility to know the accepted business purchasing methods and the purchasing policies and procedures of this organization.  If a subject is not covered by those policies and procedures then the Buyer acts in accordance with the best business purchasing standards as currently practiced or as directed by the Purchasing Manager.

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Safety First

In an Industrial setting…

It is very important that you comply with all the local rules and regulations. Your company probably provides safety equipment and its own guidelines for the performance of such work. Also, make sure Management knows what you are doing and verifies you are authorized to do this work. Continue reading “Safety First”