PaulKraemer

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About PaulKraemer

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  1. Control Panel requirements UL-508A, NFPA 70E, NEC

    Thanks Ian, That is very helpful. I'm not surprised by your suggestion to get a consultant. It would be nice to be able the get a "CE compliance for dummies" book but I had a feeling it would be more complicated than that. I see you are in Colorado. Does the consultant you use just work in your area or is he/she part of a larger outfit that serves other states? (I am in New Jersey). Thanks again, Paul
  2. Control Panel requirements UL-508A, NFPA 70E, NEC

    Hi Shiner, Thanks for your response. I had no idea, but it turns out that the shop that builds our panels is UL listed. Being familiar with our panel designs as they have built about 10 of them for us already, they say that they don't forsee any problem being able to give us the UL sticker as long as we provide them with a bill of materials proving that all components we use are UL listed. That has me feeling pretty good about UL, but I figured while I am at it, I might as well ask you about CE. On another job I am trying to quote that might end up going to Europe, I might have the requirement of putting the "CE" logo on our machine. We do try to use all CE components in our builds, but I know that there are many CE directives and I am not quite sure how to determine which directives I need to comply with. Our machines are fairly large. Each has one or two main control panels from which we run wires in conduit to different locations to power and drive motors, to fire solenoid valves for our pneumatic systems, to support operator controls like pushbuttons, selector switches, and other "smarter" controls (for example tension controllers) that are located at the point of control rather than in our control panels. I was wondering if you put the CE label on your control panels, and if so, if you could give me a clue what directives I should pay attention too and if you could tell me anything else I need to do to be able to put the CE label on our machines. Thanks again for your help, Paul
  3. Hi, The company I work for has been building machinery for the past 25 years. We used to have a full time electrician who designed, laid out, and wired our control panels in house. He was very knowledgeable and I am very confident that he followed good, recommended practices. We never had any complaints from any of our customers, some of which went through pretty extensive validation procedures. I learned a great deal from him while I worked as his assistant. When he got sick and later passed away, we never replaced him. I took over doing the electrical designs, but rather than building and wiring the panels ourselves, I just do drawings and we now have our panels built by an outside company that specializes in control panel building. I basically copied our electrician's original designs and added, changed, or upgraded whatever was necessary to meet new requirements or to deal with the fast pace of change in industrial controls. The outside control company taught me alot and I feel like we have improved and fine-tuned our designs quite a bit in the eight years that I have been doing this. I can say that I always read our component manufacturer documentation thoroughly and I follow all recommendations for wiring and fusing of all components. For our wire sizes, I follow a reference chart in one of our vendor catalogs that is an excerpt from UL 508. Still, we have not had complaints from any of our customers. We are currently quoting a new project where the User Requirement Spec says the following............ The Vendor shall ensure all electrical panels large or small meet all applicable codes: • Federal: NEC National Electrical Code, • Local codes: UL, 508A, and NFPA 70E. The Vendor shall provide the actual electronic readable and updatable MS Excel calculations spreadsheets and AutoCAD drawings showing measurements for the case of all electrical panels demonstrating compliance to NFPA 70E UL 508A, and other applicable codes requiring calculations, measurements etc.. .......... Additionally, they say that our control panels have to be "UL-508A Labeled". I am afraid to sign off on these requirements until I am sure I understand what is involved. I do not currently have a copy of the UL-508A, NFPA 70E, or NEC 2011, but before I buy these and take the time to read through them, I was wondering if anyone here has an idea of what kind of calculations and measurements are typically required to demonstrate compliance? And also, how can I get "UL Labeled"? Does this mean that I will have to hire an outside company with the proper authorization to inspect our control panels and give us the label? Any advice will be greatly appreciated. Thanks in advance, Paul
  4. PowerFlex 70 w/ ControlLogix - relate RPM to Hz?

    Thanks drforsythe, That helps. I think I'm starting to at least understand the concept of how closed loop vector control works with an encoder. I'm probably oversimplifying this, but if there were a purely linear relationship between Hz to the motor RPM and I wanted to run the motor at 1200 RPM, I would tell the drive to send 41.38 Hz to the motor. Due to load, there will be some slip and the motor might not really run at 1200 RPM. The drive would realize this (thanks to feedback from the encoder) and increase the Hz to the motor until the motor really was running at 1200 RPM. Please feel free to correct me if there is anything glaringly wrong with my simplified understanding, but if my understanding is somewhat correct, the only thing I am confused about is how to enter my speed setpoint? I am using a PowerFlex 70. From reading the documentation, it seems like there are many ways to enter your speed reference, but in all of the ways, you are basically entering it in Hz. This doesn't make sense to me when I want to enter a setpoint in RPM and have the PID loop in the drive make use of feedback from the encoder and calculate the necessary Hz to the motor in order to produce my desired RPM given the current load. Because there is not a truly linear relationship between RPM and Hz (because at different loads the same Hz will produce different RPM), I don't see how simply scaling my setpoint in RPM to a speed reference in Hz could possibly work. Thanks again - I really appreciate your help. Paul Paul: Today's variable freq. drives have stable speed regulation. By adding the encoder to the system and using closed loop vector control, the speed regulation not only gets better, but the drive can make the motor respond to changes in load. Today's drives, when operated either in open loop vector control (without encloder) or closed loop vector control (with encoder) can sense load changes and change the waveform going to the motor. Open loop (or V/Hz mode) will not regulate the speed as well and will not always detect changes in speed due to the load. I hope this helps.
  5. PowerFlex 70 w/ ControlLogix - relate RPM to Hz?

    Thanks Steve, That helps. This is my first time trying to do speed control with an AC adjustable frequency drive. I guess I am just having a hard time grasping the fact that the speed of the motor (in RPM) will be such a simple linear relation to the output from the drive to the motor (0-60Hz) regardless of any other factors such as load. With your example where I want a speed of 500 RPM and your scaling calculates 60 Hz * 500/1740 = 17.24 Hz, will 17.24 Hz give me 500 RPM both when the motor is loaded and unloaded? It seems like with this method, I am not making use of my encoder. If an output of 17.24 Hz will always give me 500 RPM, why even use an encoder? With my limited understanding, I think with my setpoint of 500 RPM, the drive would have to run a PID loop to monitor the feedback from the encoder and constantly adjust the output Hz to the motor in order to maintain the speed setpoint (500 RPM) regardless of load and any other factors that may have an effect. Any light you can shed on this will be greatly appreciated - thanks again. Paul
  6. Hi, I have an AB PowerFlex 70 EC drive with a 20A-ENC-1 encoder module with a 1024 PPR encoder. I also got the PF70 with a 20-COMM-E Ethernet/IP module so that it can communicate with my AB ControlLogix (CLX) PLC (through a 1756-ENBT) module. I want to set things up so that my CLX controls the speed reference to the PF70. I want my operator to enter a speed setpoint in RPM on my HMI. I want my CLX to send this setpoint to the PF70. I want the PF70 to control motor speed based on this setpoint (making use of the encoder). What confuses me is from looking through the PF70 documentation is that the only way I can figure out how to send a speed reference to the PF70 is in Hertz. I can't figure out how (or if) I can send it a setpoint in RPM. I have a vector duty / inverter duty 60 Hz motor with Nameplate RPM = 1740. For sending a speed setpoint to the PF70, can I simply assume a linear relationship between the frequency output to the motor (0-60 Hz) and the speed of the motor (0-1740 RPM)? For example, let's say I want to run at 1200 RPM...can I simply set my speed reference = 41.38 Hz (60 Hz * 1200/1740)? Assuming I have param 80 [Feedback Select] = encoder and I have my encoder type (quadrature) and my PPR set correctly, does this guarantee that my motor will run at 1200 RPM? Thanks in advance, Paul
  7. Hi, I have a ControlLogix PLC. I was going to use the DTOS command to convert an integer to a string of ASCII characters. The thing that I am finding tricky is that for smaller numbers, I want to add leading zeros so that my string would always have four characters. In other words, I want: 1 = "0001" 10 = "0010" 100 = "0100" ...etc... Does anyone know of a way I can do this? Thanks in advance, Paul
  8. Hi, I have a customer with a PLC5/30. They want to get a PanelView Plus as their HMI. The PanelView Plus would communicate with the PLC5 through the CH0 DF1 port. If possible, they would like to connect a PC to the PanelView Plus via ethernet (or by any other means if ethernet is not possible). They would want this PC (which would be running some VBA code inside an Excel workbook), to be able to read tags values from the PanelView in real-time. When I say real-time, it doesn't matter if there is a slight delay due to the comm interface - I just mean that they want to the PC to be able to read current tag values from the PanelView, not historical data. Can anyone tell me if the PanelView Plus has the ability to make current tag values available to a PC through ethernet or some other communication interface? If this is possible, can you give me an idea how this can be done? One possibility I thought of is if the PanelView Plus were able to act as an OPC server while the PC could act as an OPC client, but I have no idea if the PanelView Plus has this capability. Any input will be greatly appreciated. Thanks in advance, Paul .