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  1. hassankh

    Pros and cons of single phase valve actuators

    Thank you all for great answers.
  2. hassankh

    Pros and cons of single phase valve actuators

    Hello. I wonder if single phase and three phase valve actuators have any advantages relative to each other? I guess three phase motors are the preferred type so I just wonder if the two types are interchangeable in a project. Thank you in advance
  3. hassankh

    2-wire vs. loop-powered device

    Hi djs you mean the second should be used with an isolator or it is indeed an isolator itself?
  4. hassankh

    2-wire vs. loop-powered device

    According to “precisioin digital”, the term 'loop-powered' is synonymous with the term '2-wire' (meaning that only 2 connections/wires are involved in any of the connections between the transmitter, the power source and the output device). However, PRtrans and M-System (attached file)...
  5. hassankh

    Using Rosemount 644 TT

    Thank you for your kind response. I got the first part. But I still don't understand the second part. What would be the problem if we connect it to an active device that produces 4-20mA? As for the first part, this means that Rosemount 644 will always be a two-source device, one from the...
  6. hassankh

    Using Rosemount 644 TT

    In searching for conversion of 4-20mA to millivolt signal, I encountered a statement in an Emerson document as attached. It says "Conversion of a 4-20 mA source to a measurable millivolt signal constitutes a second power source in the terminal block of the Rosemount 644". I wonder why this is...
  7. hassankh

    active signal vs. passive signal

    Hello I believe this will sound as a no brainer. I wonder what is the difference between active and passive signals? Thank you in advance
  8. hassankh

    Ni-Cd Batteries in Nuclear Power Station

    Thank you all for your insightful guidance. The major conclusion I believe is that Ni-Cd is not reliable enough to provide a complete discharge which is critically needed in NPPs during loss of AC power or blackout.
  9. hassankh

    Ni-Cd Batteries in Nuclear Power Station

    Is the cost and capacity the only deciding factor? what about safety?
  10. hassankh

    Ni-Cd Batteries in Nuclear Power Station

    Most of the Standards like IEEE 535 and IEEE 666 talk about Lead-Acid batteries for nuclear power plants. Also, as far as I know, several modern nuclear power plants currently under construction also plan to use Lead-acid batteries. However, as we all know, recently Ni-Cd batteries have gained...
  11. hassankh

    AVR panel in generating stations

    We have a thermal power plant with a multi-megawatt generator of 15 kV voltage. It is connected to the grid through a 15/400 kV transformer. Definitely, the generator has its own AVR system. But I wonder if it is also necessary to have an AVR panel for the 15/400 kV transformer? In...
  12. hassankh

    DC Power Flow

    DC power flow is not meant to calculate losses. a lossless network is assumed and compared with itself, not with the real network.
  13. hassankh

    DC Power Flow

    When we perform a DC power flow, all bus angles are obtained. Then we can calculate line power flows. Then I would also like to calculate the real power injected by the reference (Slack) bus to the grid since we have not specified any power to this bus to begin with. However, the power obtained...
  14. hassankh

    T3B vs. T2B

    I guess some ammonia will be present. So I've got my answer and now I have vivid picture what is really meant by this temperature code. Thank you very much
  15. hassankh

    T3B vs. T2B

    Thank you for your kind reply. So does this mean that T2B is more likely to cause an explosion? Can the motor's operating temperature (if high) cause an ignition in the first place? Regards
  16. hassankh

    T3B vs. T2B

    Thanks for the answers. What I mean is if a T3B motor is more likely to cause an ignition in explosive space than a T2B motor because of a higher surface temperature?
  17. hassankh

    T3B vs. T2B

    I wonder if we can generally say that a T3B motor is better than T2B because of higher surface temperature? or in the contrary, can a higher surface temperature (like T3B) for a motor possibly have higher risk of causing explosion in the area than a lower surface temp. motor (T2B)? Please let...
  18. hassankh

    AC vs. DC breakers

    I heard from a friend of mine that DC breakers have higher current interruption capability than AC ones. I wonder if we can use AC breakers, maybe with some derating, for DC application? or vice versa? I have seen many MCBs and MCCBs that are used for both DC and AC application. Even their...
  19. hassankh

    Current Limiting Capability in MV Circuit Breakers?

    Thank you guys all for your great info. Shneider's current limiting capability works based on power electronic devices built into the CB which create high voltage opposed to the terminal voltage of the breaker thus suppressing the current. To dpc: interesting fact dude. To ScottyUK and...
  20. hassankh

    Current Limiting Capability in MV Circuit Breakers?

    Thank you guys. Yes, I too have only heard of fused-contactors to limit current in MV. As for the LV, correct me if I'm wrong but I believe that is why LV cables don't need to be sized for short circuit condition. Regards H

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