Emerson Exchange 365

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Continuous Pulse Output Question

Hi, Has anyone seen differences in equipment life comparing an AO Charm going to a SCR compared to a DO Charm going to a SSR?

We have historically used the AO/SCR combination and it has worked extremely well. How has the experience been for the DO/SSR combination been over the course of years? Would you recommend the DO/SSR combination for applications where long term reliability is a significant issue?

• CHARMS

Kent

• 19 Apr 2016 5:12 PM
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7 Replies

• Andre Dicaire

  

  • 19 Apr 2016 6:13 PM

  Kent, could you expand your acronyms for SCR and SSR so we are all on the same page? And what is your application. Is this a temperature control using an on/off heat source?

  Andre Dicaire

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• Kent

  

  • 19 Apr 2016 7:25 PM

  In reply to Andre Dicaire:

  SSR is Solid State Relay. SCR is Silicon Controlled Rectifier. This is for controlling the output of an immersion heater.

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• Jim Cahill

  

  • 21 Apr 2016 2:00 PM

  In reply to Kent:

  Kent, I had a brief conversation with one of our DeltaV technologists and he thought that from the CHARMs perspective, the level of reliability would be comparable between the two approaches.

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• DBacker

  

  • 21 Apr 2016 2:23 PM

  The life of the respective CHARMs seems to be only one of many criteria to be considered. The license cost of an AO DST versus the license cost of a DO DST is a consideration. Further the cost of the heater controller that accepts a continuous 4-20 mA signal (SCR) versus the cost of the heater controller that accepts a discrete Time Proportioned Input (SSR). Finally, if you already have data for the typcial service life of the respective heater controllers (SCR/SSR) that would really be informative for the rest of us.

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• Mike Link

  

  • 21 Apr 2016 2:48 PM

  In reply to DBacker:

  A DO operating as a continuous pulse output requires an AO DST, you setup the pulse frequency at the IO level and then use an analog output to adjust the on / off time. So DeltaV licensing costs would be the same for both.

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• Niklas Flykt

  

  • 21 Apr 2016 5:24 PM

  Hello,

  The pulse output is mainly used for small (under 80A) ssr -relays they usually dont have to much "Brain" inside them but they are cheap. If you need more power and  reability + different control modes you would go for a SCR also known as Thyristor power controllers. They have the power control and supervision built in so you only need to give the setpoint to them and there you can choose from differnet types of voltage or current. The newer ones can also be connected to fieldbus/modbus connections so you might save some DST license? and read the actual values from the controller. The good thing with these highteck power controllers is that they measure all the values and you can set current limits if you have limitations in your grid-feed. Here you can see a list of different control modes that these power controllers have:

  http://pages.advanced-energy.com/rs/180-YLZ-570/images/EN-OperatingModes-400-01.pdf?mkt_tok=eyJpIjoiWmpKaU5qZGxNbUpsTkRkbSIsInQiOiJ1Q2Q5OG1JNmhUeWlqKzJ4enBlVTN5K0dCVUVTZHFXYnVaWWtHNWRqK1JuMmVzZXYrNm9tb2hESHdUa2NiOWtpY1ZTK0pUT0FjWXJmM2hEUzNHS0hRRkJWOTJkZEFISVlDM0N6Z1VYN1Flbz0ifQ%3D%3D

  Niklas Flykt 

  Klinkmann Oy
  

  Key Account Manager safety products

  nikfly@gmail.com

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• Kent

  

  • 22 Apr 2016 12:44 AM

  Thank you for all the input. All my experience over the years has been with SCRs. From what I'm hearing here, it sounds like there is not a huge difference in reliability. I guess we'll be trying it.

  Thanks again for the input.

  Kent E Mitchell, P.E.

  92-H PRC

  Bartlesville, OK 74003-6670

  (918) 977-4654

  On Apr 21, 2016, at 12:42 PM, Niklas Flykt > wrote:

  Update from Emerson Exchange 365

  Niklas Flykt

  Hello,

  The pulse output is mainly used for small (under 80A) ssr -relays they usually dont have to much "Brain" inside them but they are cheap. If you need more power and reability + different control modes you would go for a SCR also known as Thyristor power controllers. They have the power control and supervision built in so you only need to give the setpoint to them and there you can choose from differnet types of voltage or current. The newer ones can also be connected to fieldbus/modbus connections so you might save some DST license? and read the actual values from the controller. The good thing with these highteck power controllers is that they measure all the values and you can set current limits if you have limitations in your grid-feed. Here you can see a list of different control modes that these power controllers have:

  pages.advanced-energy.com/.../EN-OperatingModes-400-01.pdf

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