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Inductive Coupling: A Simple Solution for Replacing Slip Rings

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Figure 1: Inductive coupling for power and data exchange

In the industrial automation space, inductive sensors have grown very popular , most commonly used for detecting the proximity of metal objects such as food cans, or machine parts. Inductive coupling, also known as non-contact connectors, uses magnetic induction to transfer power and data over an air gap.

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Figure 2: Slip ring example

While inductive couplers have many uses, one of the most beneficial is for replacing a traditional slip-ring mechanism. Slip-rings, also known as rotary connectors, are typically used in areas of a machine where one part rotates, and another part of the machine remains stationary, such as a turn table where stations on the indexing table need power and I/O, but the table rotates a full 360°. This set up makes standard cable solutions ineffective.

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Figure 3: Inductive coupling replacing the slip-ring

A slip ring could be installed at the base of the table, but since they are electromechanical devices, they are subject to wear out. And unfortunately, the signs for wearing are not evident and often it is only a lack of power that alerts workers to an issue.

An inductive coupling solution eliminates all the hassle of the mechanical parts. With non-contact inductive coupling, the base of a coupler could be mounted at the base of the table and the remote end could be mounted on the rotating part of the table.

Additionally, slip rings are susceptible to noise and vibration, but because inductive couplers do not have contact between the base and the remote, they do not have this problem.

Inductive couplers are typically IP67-rated, meaning they are not affected by dirt or water, or  vibrations, and most importantly, they are contact free so no maintenance is necessary.

Learn more about Balluff inductive couplers www.balluff.us.

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Zone Defense: How to Determine If You Need a Hygienic or Washdown Solution

It goes without saying that food safety is an extremely important aspect of the food and beverage industry. While manufacturers would naturally take precautions to ensure their food products are safe to consume, they are required to follow a set of rigid guidelines and standards to ensure the safety of the foodstuffs to prevent contamination.

CaptureTo determine which rating, standards or certifications are required for a particular food and beverage segment, you must first consider the type of food contact zone and whether it is an open or closed process.

Food Contact Zones

The food contact zone is determined by the potential contamination that can occur based on the production equipment’s exposure to food and its byproducts.

  • Food Zone: an area intended to be exposed to direct contact with food or surfaces where food or other substances may contact and then flow, drain or drain back onto food or food contact surfaces.
  • Splash Zone: an area that is routinely exposed to indirect food contact due to splashes and spills. These areas are not intended for contact with consumable food.
  • Nonfood Zone: An area that is not exposed to food or splashes but will likely be exposed to minor dirt and debris.

Open and Closed Production

In the food and beverage industry, it is also important to discuss whether the manufacturing process is open or closed. The distinction between the two plays a significant role in determining machine cleaning requirements.

  • Closed Process: A manufacturing operation in which the food product never comes in contact with the environment. All food contact zones are sealed such as the inner surfaces of tanks, pipelines, valves, pumps and sensors.
  • Open Process: A manufacturing operation in which food does have contact with the environment outside of the machine. This requires a hygienic design of the process environment, as well as the surfaces of the apparatus and components.

Required ratings, standards and certifications

Once you know the food zone and whether the production is open or closed, it becomes simple to determine which ratings, standards or certifications are required of the machinery and apparatus in the food and beverage manufacturing process.

  • Food Contact Zone — Hygienic
    • IP69K – tested to be protected from high pressure steam cleaning per DIN40050 part 9
    • FDA – made of FDA approved materials, most often 316L stainless steel
    • 3-A – certified sanitary and hygienic equipment materials and design in the US
    • EHEDG – certified sanitary and hygienic equipment materials and design in Europe
  • Food Splash Zone — Washdown
    • IP69K – tested to be protected from high pressure steam cleaning per DIN40050 part 9
    • ECOLAB – surfaces tested to be protected from cleaning and disinfecting agents
  • Nonfood Zone — Factory Automation
    • IP67 – rated for water immersion up to a meter deep for half an hour
    • IP65 – rated as dust tight and protected against water projected from a nozzle

For more information on the requirements of the food and beverage industry, visit www.balluff.com.

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Three Ways to Configure a Splitter and Harness the Power of Pin 2

Based on the increasing popularity of machine mounted I/O utilizing readily available IP67 components, it’s more important than ever to utilize every I/O point.  I/O density has increased over the years and the types of I/O have become more diversified, yet in many systems pin 2 is left unused by the end user.  Sensors tend to come in twos, for example, a pneumatic cylinder may require a sensor for the extended position and one for the retracted position.  Running each individual sensor back to the interface block utilizes pins 1,3 and 4 (for power, ground and signal) but wastes pin 2 on each port.

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Fig. 1 Bad I/O configuration: neglecting pin 2 is inefficient and costly

Rather than using a separate port on the I/O block for each sensor, a splitter can collect the outputs of two sensors and deliver the input to a single port.  With a splitter, one sensor output goes to pin 4, the other goes to pin 2.

By putting two signals into one and utilizing both pins 2 and 4, the overall I/O point cost decreases.

There are multiple ways to configure a splitter to utilize pin 2. We will review three methods — good, better and best:

1. T-splitter on the I/O block:

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Fig. 3 Good basic method for utilizing the additional I/O point, pin-2

A T-splitter is a good way to utilize pin 2.  However, the “T” covers the I/O module port eliminating the benefit of the high-value diagnostic LEDs on the block. Also, individual cables must run all the way from the block to the sensors at the installation point, creating clutter and cable bulk.  In addition, when Ts are used on a vertically mounted block, the extra cable bulk can weigh down the T-splitter and threaten its integrity.

2. V-type splitter on the I/O block:

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Fig. 4 Better way of utilizing pin 2 while also allowing visibility of diagnostic LEDs

The use of a V-type configuration allows better visibility of the diagnostic LEDs and eliminates the need to purchase a separate part. However, individual cables must still be run from the block to the sensors, creating clutter and cable bulk.

3. Y–type configuration:

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Fig. 5 Best way to utilize pin 2

In the Y-type splitter configuration, all aspects of usability are improved. One cable runs from the I/O block to the installation point. The split of pins 2 and 4 is done as close to the sensors as possible. This significantly cleans up cable clutter, provides a completely unrestricted view of the diagnostic LEDs and allows for easy installation of multiple connectors to the I/O block.

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Not all IO-Link Masters are Born Equal!

IO-Link as a standard for device level communication has been around for over a decade. It has started gaining huge momentum in the Americas with 60-70% growth in IO-Link integration in 2017 alone (awaiting official numbers from the IO-Link consortium). Due to this huge market demand for IO-Link, there has been an insurgence of IO-Link masters with features and functionality that is dazzling machine builders and end users alike.

IO-Link Consortium Data (global)

While IO-Link as a communication platform is a standard (IEC 61131-9), the added features and functions leave some machine builders confused on how to reap benefits of these different masters that are around. Some machine builders have a thought process of “Hey, vendor A is selling an IO-Link master and vendor B is also selling an IO-Link master – they are both IO-Link so, why should I pay more?” These machine builders are choosing the lower cost options without realizing what they are missing out on – and sometimes getting disgruntled about the technology itself. On the other hand, some machine builders are spending too much time in measuring and testing a variety of masters – wasting precious time and materials to identify what fits best for their solution. With this blog post and my next, I am hoping to add some clarity on how to detect differences quickly amongst the masters and make a decision that is best suitable for the applications at hand.

IO-Link started out as a standard of communications for smart sensors with a focus to eliminate variety of different interfaces on the plant floor- but since its inception it has manifested itself to be much more than simple sensor integration. It has also gained significance as a backbone for enabling Industry 4.0 or IIoT.  So, let’s review different types of IO-Link masters.

The very first thing machine builders have to do is determine whether the IO-Link master should be IP20 (in cabinet) implementation or IP65-67-69 rated (machine mounted) implementation.

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The machine mounted version makes sense as it is suitable for most industrial environments. The IP20 version may be desirable if the machine is operating in extreme environments or experiences continuous changes in temperature, humidity and other factors.

With machine mount masters:

  • It is easier to debug the system with onboard diagnostics availability
  • Eliminates wiring and terminates hassle and saves time and money during the machine building process.

If the IP20 master is your choice, then there isn’t a major difference between vendor A and vendor B IO-Link masters. The difference could appear based on whether the IO-Link master is a part of a larger system or stand-alone module connected to the machine controller through one of the fieldbus or network gateway.  One more thing to note about IP20 masters is they are meant for connecting 3-pin IO-Link devices only. If you want to use architectural benefits of having added Vaux (separate output power) then using IP20 masters becomes complicated and quickly becomes expensive.

If the initial features of machine mounted masters are appealing to you, then there are a few more decisions to be made. The machine mounted IO-Link masters (for simplicity let’s call them IP67 Masters) range from “sensor only” integration capable masters to the ones that have the ability to become a backbone for flexible modular controls architecture. There are primarily three different types of masters as shown below in the chart and they differ based on the power routing capabilities and power handling capabilities.

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In my previous blog entry, “Demystifying Class A and Class B Type IO-Link Ports” I discussed the differences between Class A (Type A) and Class B (Type B) ports and the implications of each type.

We will go over more technical details in my next blog (part 2) to see how power routing and current capabilities make a difference between sensor only applications and a total architecture solution.

To learn more about IO-Link masters, visit www.balluff.com.

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IP Ratings and ECOLAB Basics

WashdownSensorsIntegrating sensors in washdown applications can be confusing when considering the various approvals.  So what do they all mean?  If a sensor is an IP69K rated sensor does that mean it will survive everything?  In the world of sensors there is IP54, IP67, IP68 and IP69 so if my sensor is IP69K that means it is the best right?  The short answer is no.  Let’s take a brief look at the differences.

IP ratings will generally have two digits with the first digit referring to the solid particle protection.  The second digit indicates the level of protection against the ingress of water.

Sensors rated for IP54 indicates they are dust protected, meaning that dust can get inside the sensor, however, it cannot be enough to interfere with the operation of the equipment –  this is designated by the 5.  The 4 indicates that the sensor withstands splashing water on the housing from any direction with no detrimental effect.  The test for the splashing of water lasts at least five minutes with a water volume of 2.64 gallons per minute with a pressure of 7.25 to 21.76 PSI.

IP67 rated sensors are the most commonly used sensors on the market.  Even most electrical enclosures used in automation are IP67 rated.  The 6 indicates these devices will not allow the entry of dust.  The 7 indicates that the sensor can be immersed in water to a depth of 1 meter for 30 minutes.

IP68 rated sensors are dust tight sensors that can be immersed in water continuously under conditions specified by the manufacturer.  Typically the depth of the immersion is 3 meters.

The IP69K rating is based on a dust tight sensor that can withstand high pressure sprays.  The devices are sprayed with a pressure of 1,160 to 1,450 PSI.  The water temperature can be as high as 176°F with a flow rate of 3.7 to 4.2 gallons per minute.  The distance from the nozzle to the device is 4 to 6 inches.  The sensor is placed on a rotary table that rotates at 5 revolutions per minute and the sensor is sprayed for 30 seconds at four angles 0°, 30°, 60°, and 90°.

The ultimate sensor would have a rating of IP67/IP68/IP69 indicating that it will survive submersion and high pressure washdown.  Also, some of these sensors are 316L stainless meaning they have low carbon content and are more corrosion resistant than other stainless steel grades.  Are all IP69K sensors stainless steel?  No, some sensors utilize polycarbonate-ABS thermoplastic.

Usually during washdown applications in the food and beverage industry the spray is not just water but some sort of cleaning chemical or disinfectant.  These aggressive cleaning and disinfecting agents can attack different housing materials.  This is addressed by the ECOLAB certification.

The ECOLAB test consists of testing the housing and sensor materials to exposure to these aggressive cleaning and disinfecting agents.  The devices are tested for 14 to 28 days at a room temperature of 68° F.  During this time the sensor is visually inspected for swelling, embrittlement, or changes in color.

Don’t forget that even though the sensor has the correct IP rating for your application that the mating connector has to meet the same specifications.  For example, if the sensor is IP69K rated and a IP67 mating cable is used then the lower IP rating has precedence.

If you are interested in what sensors and cables meet washdown requirements, please visit www.balluff.us.

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2 Simple Ways to Protect from Arc Flash Hazards

If you are a manager at any level of a manufacturing facility, I hope you are aware of the dangers of arc flash.  For those who are not aware, “an arc flash, also called arc blast or arc fault is a type of electrical explosion that results from a low-impedance connection to ground or another voltage phase in an electrical system.”  Typically this does not occur in 120V situations, but can occur in 480V+ installations if proper precautions are not taken.  Employees can be severely injured or even killed when an accident occurs while working with these kinds of electrical systems.   There are many standards  like OSHA, IEEE and NFPA that regulate these types of situations to provide a safe working environment for the employee.  In addition to those standards, I would propose two simple changes to controls architecture and design to help limit the exposure to working inside an electrical cabinet.

Continue reading “2 Simple Ways to Protect from Arc Flash Hazards”

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Machine Mount I/O: Get out of the Cabinet

In April, Jim Montague of Control Design wrote an interesting article on Machine Mount I/O entitled “Machine-Mount I/O Go Everywhere.”  I think the article makes some very good points as to the value of why someone wants to move from inside an enclosure, or controls cabinet, to mounting I/O products directly on the machine.

He summarizes, with the help of a number of industry experts, the below points:

  • Same or Better control performance out of IP67 products versus IP20 products.  
    • Installation time alone “is reduced by a factor of 5 to 10”
    • Assemble more controls equipment faster with the same people & workspace
  • Smaller & Simpler components take up less real-estate on the machine
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Defining IP Ratings and NEMA Ratings

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As I was preparing to write my blog entry, I was browsing my e-mail and came across an article in the October Issue of TIA Newsletter (Totally Integrated Automation) from Automation World, concerning IP Ratings.  I found the article , very informative as it broke down the different degrees of IP ratings, as well as some similarity and differences between IP ratings and NEMA ratings.  I only wish there was some information involving IP69K. 

This article, IP Ratings – What are they and what do they mean,  is a great starting point to learn about IP Ratings, I suggest you stop by and read it. 

For more information about IP67, check out The Secret of IP67 Protection.

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One M12 Port = Endless Possibilities

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Paradigm shifts in automation are always occurring. The need for cost savings and higher diagnostics caused the shift from IP20 I/O to IP67 I/O.  Now, we are in the midst of a shift to reduce or eliminate enclosures in industrial applications by removing control and power from the cabinet.  With the reduction of IP20 I/O and enclosures, adding more I/O (discrete and analog) or specialty devices (RF identification, measurement devices, etc…) is now more difficult.  In the past it was relatively easy, but expensive, to add another “slice” of I/O to an existing IP20 solution.

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Get Rid of Remote I/O Cabinets Once and For All

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Every time I travel, customers tell me, “we just wire everything into a box.”  Every equipment designer goes through a phase of their design process where they need to decide how their I/O gets from their sensors and their valves to their controller.  Some people use I/O cards on their PLC, or networks with IP20 solutions inside remote I/O cabinets.

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