Blog

AC Drives in Extrusion Machine Systems

Posted April 19, 2016 by Pepper Hastings

Categories: Blog, Yaskawa Drives

Tags: , , ,

A lot has been written and said about AC drives in extrusion machine systems. And about DC drives in extrusion applications. Let's get to the basics.

  1. Even though the DC drive is more efficient than the AC drive, the AC motor is more efficient than the DC motor by a much greater amount. So overall, the AC system is more efficient than the DC system.
The extrusion industry for years favored DC drives to control the big DC motors. But is that still the best practice in 2016?

The extrusion industry for years favored DC drives to control the big DC motors. But is that still the best practice in 2016?

2. The AC system has a Power Factor of about 98% whereas the DC system varies proportional to speed from about 1% to 82%. Thus, the overall power distribution system is more efficient with AC than with DC.

Now, for some more details.

Line Notching

  • DC drives switch line voltage to the motor using a Phase Control method; the AC drive switches the line using a diode to a DC bus.
  • SCR switching will cause line notching (due to the relatively slow turn off time) which can be devastating to adjacent equipment. With the AC drive, diode switching does not cause line notching due to its relatively fast turn off time.

Extrusion machine’s control system’s response

  • The plastics industry for years considered DC king because of its speed regulation with tach feedback. AC did not rate because it had poor speed regulation.
  • Today, through Vector Control, the AC system without feedback (Open loop vector) will perform at least as well as the DC with tach feedback and AC with Encoder feedback can outperform DC with tach feedback.
  • I acknowledge that DC can perform as well as the AC if the DC system can use encoder feedback.

Extrusion system reliability comparison between AC and DC drives

  • DC is inherently more reliable than AC since it has fewer parts to fail (until you take the Motor into account).
  • AC is inherently less reliable than DC, until you take the Motor into account, since it has more parts than DC.
  • However, the DC system is less reliable than AC in that the major failure point of the DC system is the DC motor.
  • The DC motor brush system is a high maintenance item giving rise to an inherently weak link in the system.
  • A DC motor failure has a high probability of causing a DC drive failure as collateral damage.
  • The DC drive system can also be less reliable than AC since it depends upon the AC utility line switched by SCRs to control the current to the DC motor.
  • In the event of a motor failure, the SCR will continue to conduct till:
    The AC line commutates to the opposite polarity or,
    The AC line fuse blows whichever comes first.
    The latter is many times the result of the former.
  • With the AC system, the transistor is switched off much faster than the SCR.
  • The AC drive can detect the high current of a motor failure and switch off before blowing a fuse or damaging an AC drive component
  • Many AC drive manufacturers’ systems still cannot detect a destructive fault and will fail as a result of the motor failure.

Why Yaskawa Matters in Extrusion

  • Yaskawa has broken the reliability curve (better stated that Yaskawa has SMASHED the reliability curve) of all other solutions.
  • Yaskawa has, by nature of their quality process, their design criteria, and their excessive attention to detail, made the most reliable drive on the planet
  • Yaskawa’s patented transistor system does in most cases turn off before a catastrophic failure can occur.
  • Here is an application paper on Yaskawa and extrusion machine applications.

Conclusion

  • When planning what to do with your extruder's DC drive system, consider the following: AC beats DC for performance; AC beats DC for energy savings; Yaskawa AC trumps DC for system reliability; chose an systems integrator who has experience with DC to AC retrofits.
Lyons

Lyons

Steve Lyons is a member of the Houston engineered solutions team and is widely known as an industry authority on AC drive applications in control systems, including extrusion, centrifuge and many others. You can reach him at steve.lyons@iidm.com

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VFD on Fans, Pumps or Blowers

Posted April 11, 2016 by Pepper Hastings

Categories: Blog, Yaskawa Drives

Tags: , ,

Why use a VFD on Fans, Pumps or Blowers? First, visualize your production facility:

  • How many fans are started and stopped using a starter.
  • What about pumps and blowers?
  • How many of those use a started to control stopping and starting?
  • Are you able to control the speed or flow?
Using a VFD on pumps, like this sewage treatment pump, can reign in energy costs and extend the life of the motor running the pump.

Using a VFD on pumps, like this sewage treatment pump, can reign in energy costs and extend the life of the motor running the pump.

Biggest question (and most costly) is: Are you wasting money and energy?

These are just a few simple questions that should start you thinking about better application control, which most times leads to energy savings. A variable frequency drive (VFD) might be your answer.

 

Simple Math Proves Savings

Most pumps, fans and blower systems are powered by induction motors. The energy used by an industrial induction motor is a function of the speed it runs at. In an induction motor, the power used by the motor varies depending on the cubed value of the motor’s speed. If the motor’s speed is raised, energy consumption increases. If the motor’s speed is lowered, so is energy use.

When you use a starter to start that induction motor, the motor comes on at full rated speed. This creates an inrush of electricity as well as full wear and tear on the motor and the motor housing. VFDs have the ability to run motors at a percentage of rated speed and, with limits, even above rated speed if desired.

Now about that energy savings. If you use a VFD run a motor at 50% rated speed, you are reducing the energy it takes to run the motor at rated speed by nearly 88%. How did I get this you might ask? Take the .5 speed and cube it. That is .5 x .5 x .5 = .125 or 12.5%. This means at half speed you are only using 12.5% of the same energy at full speed: That’s an 88% reduction. It sound like a lot of math, but contact me and I can walk you through it if needed. We do a ton of VFD work so I am happy to help.

Yaskawa Electric has an awesome online tool called the Yaskawa Energy Savings Predictor for estimating your own energy savings. Plug in some parameters and see what you think.

Without a VFD on a fan, or pump or blower, there is no other way to reduce the speed to realize this kind of savings. On pumps you may have a control valve. This valve controls flow or pressure. This consumes the same amount of energy on any position as motor speed is at rated speed the entire time. Fans might use a 2-speed motor but those motors lack the capability to vary motor speed to keep within the application needs. A VFD allows you to take process inputs and better control your application needs on fans, pumps and blowers.

Dan Mahoney

Mahoney

Dan Mahoney helps plant engineers and automation and controls planners in the Houston area for Innovative-IDM. He's a member of the President's Club and can be contacted at dan.mahoney@iidm.com

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Outsource to a Contract Manufacturer: Make or Buy?

Posted April 5, 2016 by Pepper Hastings

Categories: Blog

Tags: ,

Have you considered taking some of your manufacturing process and doing an outsource to a contract manufacturer? In many instances, your decision will depend on your core competencies and where you want to allocate your time and resources.

One of the most common questions in a factory is: Do I want to MAKE IT, or BUY IT?

There are many reasons why a company may decide to outsource a process to a vendor.

  • cost reductions
  • space utilization
  • resource allocation
  • quality improvement

Jack of all trades, master of none

More and more companies are realizing that it takes a great effort to maintain a process in-house where the process is not part of their core capabilities. For example, an OEM that designs and builds CNC Metal Cutting Machines is great at manufacturing said machines, but not so great at building cable assemblies.

Another example: An OEM that is amazing at designing and building Industrial Water Pump Systems, but not so great at building Industrial Control Panels. Or how about a Communications company that design and build best in class Satellite Antenna Products, but struggles with low voltage electronics assemblies?

10-questions-gemba-walks-infographic

A contract manufacturer committed to lean production methods can come to your plant and do a Gemba walk. Infographic source: www.traccsolutions.com

When to Outsource to a Contract Manufacturer

Making a "Make or Buy" decision to outsource to a contract manufacturer can be simple if you ask yourself the following questions:

  1. Is this a proprietary process of our core products? Is this process part of our core capabilities?
  2. Will outsourcing this process reduce the quality of our products? If you answer no to these questions, then more than likely the process is a good candidate to outsource.

See, there are companies built to service these specific processes, for example, metal fabrication shops, cable assembly shops, industrial control panel shops, etc. They have the equipment, tools, space, and expertise to deliver quality products to their customers, and, therefore, can offer great quality parts and service at an affordable price. Bringing in-house a process requires a big invest in capital equipment and people. Regardless of the current backlog and the state of the business, companies have to keep their investment in equipment and people productive. If a process is outsourced, then the burden is passed on to a business diversified in the specific process. Or, if the orders stop coming in, and the process is kept in-house, then companies find themselves in a predicament.

I find that doing a Gemba walk is the best way to figure out which internal processes are good candidates to outsource. Gemba is a Japanese word for The Place, a Gemba walk is when you walk to The Place where humans are creating value for the customer. Doing the Gemba walk gives you the opportunity to speak with the process owner, who are those people in the front lines adding value to the customer.

The welder, the wiring tech, the assembler, the operator....It’s incredible how quickly they let you know what bugs them, what tasks are those that they wish they didn’t have to perform. More than likely someone has a machine that performs that task more efficiently and at a lower cost. And even better, they are probably just down the road. When you remove the tasks that bug your best employees, and when you improve their morale by eliminating what bugs them, then you improve your business on a human level.

No matter who you choose as a contract manufacturing partner, make sure they have the  space, tools, quality systems, and most importantly people who know how to produce a really great looking control panel. I love doing Gemba walks. Contact me and we can do it together at your place.

Luis Santeliz

Santeliz

Luis Santeliz is Innovative-IDM’s Lean/Process Manager, he has a B.S. Degree from Northern Illinois University in Manufacturing Engineering Technology. You can contact him at luis.santeliz@iidm.com.

 

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Fire Damaged Control Panel Repaired

Posted April 1, 2016 by Pepper Hastings

Categories: AC Drives, Blog, field service

Tags: , ,

The wastewater plant called Friday morning, needing an emergency repair on a fire damaged control panel. The thing  had gone up in flames. Click on the photos below for more of the gory details.

This customer is about two hours away. I scrambled to get together parts I thought I might need and hit the road. On the way out there, my network of co-workers put together an email containing drawings and DC drive settings from when we had modified the system (more than 10 years earlier). I also had a parts list and an explanation of how the machine, which the panel controlled, was supposed to operate.

When I arrived onsite I was told again how critical this fire damaged control panel was to the operation. The panel controlled a centrifuge at a municipal wastewater treatment plant. A speedy repair was critical.

Opening the panel revealed charred components top to bottom. Most of the insulation had burned off the wires, and no labels were to be found. I started pulling out the destroyed and damaged parts and wires.

By Friday evening, I had most of the panel empty, a new Bardac drive ordered for Saturday delivery, and a list of necessary parts. I returned to Houston, collected the relays, timers, contactors, and wires that I would need to rebuild the panel.

Saturday, I returned to the wastewater site and worked all day cleaning out the panel and installing all the parts. There were three sets of drawings for this machine because it had been modified a several times. Much of the new wiring had to be done based on how they wanted it to work, rather than following the drawings. I had to again call in for some backup help from colleagues to get the old drive settings in to the new unit. By Saturday night (around 11 p.m.), the centrifuge system was again operational.

Jon McPherson

McPherson

I returned a couple of times the next week to clean up the panel, install new Delta-wye start contactors, and build and install the necessary mounting brackets. The customer was excited to have the system working again.

Jon McPherson is an Innovative-IDM field service technician based in Houston. You can contact him at jon.mcpherson@iidm.com.

 

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Oklahoma City Technology Expo April 6

Posted March 24, 2016 by Vanessa Muse

Categories: Blog

Tags: , , , , , ,

Oklahoma City Technology Expo

If you are in the Oklahoma City area on Wednesday, April 6, stop by our Technology Expo. Open house, and lunch is included. Factory technology experts will be on site to answer your questions about pneumatics, motion, automation, I/O, machine controllers, robotics and more.  Raffle prizes for the first five people in the door. See you there!

 

Oklahoma City Technology Expo
Lunch and Learn
Wednesday, April 6, 2016
10am to 4pm (open house)

Residence Inn Marriott
1111 E I-240 Service Road
Oklahoma City, OK 73149

 

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