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  1. PaulBr

    Tap Conductor rules in IEC standards

    In USA per NEC (National Electric Code) definition: Tap conductor is Conductor with an upstream overcurrent protection whose rating exceeds the maximum ampacity of the conductor. NEC has some rules that limit length and ampacity of tap conductors. Are Tap Conductor rules unique to NEC or there...
  2. PaulBr

    VFD cable and compression lugs

    Is VFD cable requiring special compression lugs? In our application we are using 500 MCM VFD cable, Lutze A2205003. Link We intended to use compression lugs 500 MCM compression lugs, Punduit LCA500-1-6 with this cable: Link However, when conductor is stripped from isolation fine strands...
  3. PaulBr

    Is it IEC (CE) requirement to provide assisted start to 3 ph induction motor above certain size?

    Hello guy: Does anyone know answer to question in subject line? If it is indeed requirement, can relevant documents to be sited? Motor in question is regular 3 phase squirrel cage induction motor. If this is just good practice in IEC world, then when (motor size) it needs to be used? Best...
  4. PaulBr

    61000-6-2 Electromagnetic Compatibility (EMC) for industrial machinery

    Hello fellows: How this standard, 61000-6-2 Electromagnetic Compatibility (EMC), is applied to industrial machinery. Words in standard are saying that it is applicable to "electrical and electronic apparatus". In our case industrial machine consists of several devices (apparatuses), like VFDs...
  5. PaulBr

    IEC frame size motor terminal boxes and imperial size conduits

    Does anyone has recommendations how to connect imperial size conduits to metric sizes openings in motor terminal boxes. Machine is being built in China. All motor equipment is using IEC motors with metric size openings terminal boxes. However all conduits and fitting required to be PVC coated...
  6. PaulBr

    PowerFlex 525 and 753 current rating.

    We have started using new families of Rockwell Automation drives, PowerFlex 525 and Powerflex 753. In the drives manual there is chart that showing drives input current rating and output current rating. On these charts output current rating is greater than input current rating. It is opposite...
  7. PaulBr

    Motor current, when drive in sensorless vector and scalar mode

    We have pump driven by 37kW motor, which is controlled by PowerFlex 70 drive. When drive is configured as scalar, V/Hz mode, motor cannot run faster than 15-17Hz. Drive is displaying about 67-69Amp and going in current limit mode protecting motor. When drive is configured as sensorless vector...
  8. PaulBr

    Is VFD cable ground conductor current carrying conductor?

    Is ground conductor in VFD cable carrying current? Do we need to count this conductor for derating purpose? NEC states that in 4 wires Y system, when non linear load with a harmonic currents, neutral conductor needs to be counted as current carrying conductor. VFD is not 4 wire system but it...
  9. PaulBr

    Several motors or loads on one branch circuit NEC430.53

    I am looking for some help. For HVAC unit I have three Copeland compressors units, which are connected (piped) in tandem. Each compressor rated three phase 460V, 60Hz,load current is 18.6 amp. Each compressor will operate from its own contactor rated for 34 amp equipped with electronic overload...
  10. PaulBr

    CE conformity to EMC directive

    We are OEM company. In the equipment we make we are using drives, which are carring CE mark on them. Drive manufacturer has EC declaration of conformity of these drives to the european directives. These are 480VAC, 7amp and 10amp input rating drives. My question is about EMC directive. What...
  11. PaulBr

    Drive Emergency Stop

    I have seen recently that few drives manufacturers (Indramat, Control Technique, Rockwell Automation) are providing feature of Safe OFF or Safe Disable, which are certified as a means of removing power without phisically braking power circuits. I got new copy of NFPA79 2007. It is saying that...
  12. PaulBr

    speed winder vs. torque winder

    We are designing slitter-rewinder machine. This machine will be used to unwind various narrow (up to 17" wide) web materials like paper or films, slit them these materials to multiple streams and rewind these multiple streams on the individual cores. Example is the web with 5-6 rows of printed...
  13. PaulBr

    Reactor and EMC filters

    Are line reactors and EMC filters placed at the input of VFD serving the same purpose? We are OEM. Machines that we make have incoming 3 phase power - line reactor - EMC filter - VFD (3HP or 5HP Unidrive SP by Control Technique). Most likely we would need to have EMC filter because these...

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