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  1. Noway2

    Disconnect sizing question

    I am working on a project to replace a steam meter panel (enclosure) and the project sponsor wants it to be built to UL508A. He is also telling me that the max available fault current at the building transformers where these will be installed is 65KA and he wants the panel to have a rating...
  2. Noway2

    Billing Software

    Thank you for the feedback, I appreciate it. EnergyCAP is one of the ones that has been floating to the top of the list. It is good to see another recommendation for it from a different perspective than a university peer. Import of the monthly data seems to be one of the common troubles with...
  3. Noway2

    Billing Software

    This is probably a bit of a stretch, given that it's a pretty niche area, but I thought I would ask and maybe find that someone does have a suggestion. I work as an Engineer for a university in their energy services division that provides several utility services to campus, including steam and...
  4. Noway2

    Failures of ABB drives

    Here is an example of one of the phases showing the voltage and corresponding current. There does not appear to be any sort of voltage 'spike' precipitating the incident. https://files.engineering.com/getfile.aspx?folder=1cea74ae-998c-4c9a-b4d5-b67647c25ec6&file=v1_i1_5_28_18.jpeg
  5. Noway2

    Failures of ABB drives

    We have an chiller / cooling tower installation that is using these new direct drive / permanent magnet motor application that requires a special VFD that runs at about 7Hz maximum speed. I do know that these were the first of this size in this application. We have three of these installed...
  6. Noway2

    Question about multiple VFDs on a single feed

    First, I would like to thank everyone for the replies. This is a subject we've been down before with this installation, to which we're expanding the capacity. On each of the installations, we've done the IEEE519 modeling and it has said put the filters in but in reality, we've questioned their...
  7. Noway2

    Taking the Professional Engineer (PE) Exam

    My state, North Carolina, will allow you to take the PE without the EIT / FE with 20 years or more of engineering related work experience, at least four of which must have been under the supervision of a PE. I am 3.5 years into the four year part and have roughly 19 years of work experience...
  8. Noway2

    Question about multiple VFDs on a single feed

    I have a question about an unusual installation. The current situation is as follows: 12.4KV utility service to a step down transformer that reduces the voltage to 4160V. The 4160 feeds a chiller VFD through a motor disconnect. We're looking at adding another variable speed chiller. One of...
  9. Noway2

    chilled water system controls

    Is your piping really designed as shown in the diagram in the initial post? This doesn't look like a primary secondary loop. It looks more like a variable primary (lack of bypass on the chiller output) without the VFDs on the buildings.
  10. Noway2

    chilled water system controls

    With constant flow / three way valves, you are undoubtedly going to have to make some form of trade off: efficiency, chiller cycles, or temperature and humidity control. In the worst case (and I've seen this happen in your situation is that you get a serious mold problem). About the only thing...
  11. Noway2

    What mistake from your past did you learn the most from and how has it shaped you today? HR Qs

    It has been my experience that a common indicator of this being about to happen is when middle managers are suddenly having a bunch of closed door meetings with each other.
  12. Noway2

    What mistake from your past did you learn the most from and how has it shaped you today? HR Qs

    Always remember that in every stage of the interview, they are looking for a reason to NOT hire you, not a reason to hire you. Many of these questions are opportunities to see if you will stick your foot in your mouth given a chance and your objective is to decline the opportunity. As far as...
  13. Noway2

    Chiller Plant Operation Seminars?

    This is inline with the response I received from the Raleigh office rep, who also explained that the information isn't really available online either. The response is below. From the reply, If your willing to share your location, at least down to the nearby major metropolitan area, I can get...
  14. Noway2

    Chiller Plant Operation Seminars?

    DOH!, here is the link: http://www.training.carrier.com/commercial/hvac/general/0,,CLI1_DIV44_ETI12280,00.html At closer look it also shows that it has a list of class locations and schedules. I have also contacted the local office to see if they have any recommendations.
  15. Noway2

    Chiller Plant Operation Seminars?

    Here is a link to a site about their training. It looks to me like a site where you can order the training modules. The course I took was held in Raleigh, NC and they brought a couple of guys down from Syracuse to teach parts of it. I will contact the person in charge of the course I took and...
  16. Noway2

    Chiller Plant Operation Seminars?

    I meant to say Carrier not Carries. Sometimes I really wish we had an edit function!
  17. Noway2

    Chiller Plant Operation Seminars?

    Carries has a Technical Development Program that covers all aspects of HVAC systems from psychrometrics to chiller design. It is a 10 week, one evening per week program, and costs about $500. The book material alone that you receive as part of the course is well worth the $500. I took the...
  18. Noway2

    Convert Small signal pulse to RS-232 signal levels?

    I just took a closer look at your scope trace, based upon your comment about tying to capture it with a scope. Notice the ring pulses at both edge transitions. This could indicate interference between the pulse and your scope probe, possibly cause by the inductance of the probe (i.e. a snap...
  19. Noway2

    Convert Small signal pulse to RS-232 signal levels?

    This reminds me of something that I encountered in my last major circuit design. The rise and fall time of these signals can be of critical importance. If one is using programmable logic, e.g. an ASIC or FPGA, the rise times of those circuits can be ridiculously fast (1-2ns). At these rates...
  20. Noway2

    Convert Small signal pulse to RS-232 signal levels?

    Be sure you check the worst case specs, lowest output from micro with highest requirement of the CTS. From experience, I would recommend placing a cheap transistor in the line as a switch. This way the micro can toggle the switch with little to no current draw and you can get a full swing with...

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