Category Archives: Other

PLC vs. DCS: What’s the difference?

Before we get into the differences of a PLC’s and DCS’s, we need to talk about what each of them are designed to do.

What is a PLC?

A PLC, or Programmable Logic Controller, is a computer that has been adapted to specifically meet the needs of any specific manufacturing process. These devices come in many different shapes and sizes, with many options for digital and analog I/O, as well as protection from high temperatures, vibration, and electrical noise. The invention of the PLC allowed computers to be streamlined into the industrial automation process.

A PLC can be a single device calculating and executing operations, or a rack of different modules may be used to meet whatever your automation system requires. Some of the additional components include processors, power supplies, additional IO, interfaces, and much more.  Every part works together to be able to run open or closed loop operations that are rated at high speed and high precision. Take a CNC machine for example; a PLC would be used to control positioning and motion, as well as torque control. These devices are popular because they are very inexpensive relative to the amount of power and how many hours you get out of them.

 What is a DCS?

A Distributed Control System is an automated control system that streamlines the functionalities of the various devices that are used throughout an entire work space. This type of system uses many different controllers to allow all the machining parts to talk to each other as well as computers that can input parameters and display information such as power usage, speed, and much more. These controllers are distributed geographically across a plant to allow for high-speed communication to the control room. When using different types of modules however, the system may require different communication standards such as Modbus and Profibus. DCS’s started coming to fruition throughout the 1960’s once the microcomputer was brought widespread into the market.

Then what exactly is the difference?

A PLC will probably be used to control a machine that isn’t too complex wheres the DCS can have total control of all the operations in an entire plant. The PLC is preferred in situations where the machine does not have to worry about meeting specific conditions inside the plant. These conditions typically involve operations that may need to stop or restart, as well maintaining precise temperatures. A DCS will be able to take advantage of all the aspects of an automated system, from the machines and sensors to the controllers and computers. An entire DCS is much more expensive than a few PLC’s, but each have their advantages in any given situation and certain automated systems will always require one over the other.

Visit MRO Electric and Supply’s website to see all of our available Programmable Logic Controllers. If we don’t have what you need listed on the site, contact us at sales@mroelectric.com or (800)691-8511 and we will be happy to help.

What are circuit breakers?

A circuit breaker is a preventative safety device that detects and stops a circuit if the current is insufficient or in excess. These devices help insure the stability of the electric current in our buildings. Unlike fuses, breakers are reusable and can be consistently relied upon to break a circuit to protect us from potential electrical fires.

How do they work?

A breaker is comprised of a few basic components. A switch is connected to an electromagnet that allows electricity to flow from the bottom to the top terminals.

Source:
http://spmphysics.onlinetuition.com.my/2008/06/uses-of-electromagnet-circuit-breaker.html

With current running through the electromagnet, it becomes magnetized. If the current is suddenly increased, the magnet becomes strong enough to pull down a metal lever attached to the switch linkage. By doing so, the contacts are broken and the electricity is powered off.

What’s the difference between certain breakers?

Residential Circuit breakers- Used in common household wiring to protect electrical appliances like refrigerators, washing machines and fans. Electrical panels can also be designed to have one breaker controlling one specific or multiple outlets in a room that shut off when overloaded.

Industrial Circuit breakers- Used with much larger electrical current applications for warehouses, factories, and other large industrial locations. They can be used to insure safety of the plant equipment, lighting, business systems, air conditioning and wiring.

Voltage– Describes the ‘pressure’ of the electricity. The most common voltages of breakers are . Most household voltage is 120V, with larger appliances around 240V.
Amperage– Measures strength of the current in amperes. Common amperages include 15A, 20A, 25A, up to 6000A.
Pole number– Describes the number of completely separate circuits that can be protected by a circuit breaker at the same time. These include single-pole, double-pole, triple-pole and tandem pole breakers.
Installation location/External Design– Breakers can be designed to be indoor or outdoor based on the application. Different enclosures can be made to withstand different weather conditions.
Interrupting Mechanism– Other breaker designs include air circuit, oil circuit, vacuum circuit, MCB, MCCB, GFI, GFCI and AFCI breakers. While these all serve the same purpose of breaking electrical current in the event of unstable electric power consumption, they have different means of interrupting the current.


Visit MRO Electric and Supply’s website to see all of our available Circuit Breakers. If we don’t have what you need listed on the site, contact us at sales@mroelectric.com or (800)691-8511 and we will be happy to help.

Considerations for buying automated parts

What are automated parts used for?

Automation is crucial in manufacturing and is the backbone of our industries. Robots can automate highly variant, dangerous and exhausting tasks in a high-quality and cost effective way. By increasing productivity at a lower cost, maximum cost efficiency is reached, which is ideal in a business setting.

What should I be looking for when buying automated parts?

There are a number of things to keep in mind when buying automated parts for your warehouse or setup. Below is a basic guide with questions to ask yourself to make the process a little easier.

Is there a warranty? If so, for how long?

Protect your investment on your automated parts. Warranties are important in insuring that your part is functioning as intended and in getting what you paid for. Make sure you check under what instances a warranty can be claimed and how long the warranty lasts. Are there detachable parts within the automated component that are covered? MRO Electric and Supply offers a minimum 12-month warranty on all listed parts.

Is the part compatible with the machinery that is already there?

There are a multitude of environments that certain parts can be more oriented towards, including in aerospace and automotive manufacturing, food processing plants or laboratories. It is essential that the part be used in the correct application to be effective. It is obviously important that the automated component works with the setup already in place. Some additional compatibility questions to ask yourself before buying:

Does the weight or form factor impact its compatibility? Is space an issue?

Many people are eager to buy large parts for their warehouses without considering the space to put them. Consider the part and its intended configuration. Include additional equipment that comes along with the part like peripherals, fencing, light curtains or mat guards.

Will the condition of the part affect its lifespan in this application? Is there a newer, better part for this application?

Check to see if the part is new, used or refurbished, and if the condition will affect its application. Many industrial parts are discontinued as new technologies evolve, and while these legacy parts are still useful, newer components might work more efficiently or effectively. Check to see if there are any advantages or disadvantages to older and newer generations of your part and weigh your options.

Visit MRO Electric and Supply’s website to see our selection of automated parts from manufacturers like Yaskawa, Modicon, Control Techniques, Siemens, and FANUC. If we don’t have what you need listed on the site, contact us at sales@mroelectric.com or (800)691-8511 and we will be happy to help.