Current transducer

Discussion in 'General Electronics Chat' started by miloboy, Jun 1, 2010.

  1. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    790
    You have not clearly specified your measurement requirements.

    It would help if you did.

    Suppose you want to measure a load current of up to 15A rms (which you indicated as a possibility in an earlier post) ....

    Wire the primary with 1 turn - say by putting all 3 PCB connections in parallel. You will not burn anything out since with 3 parallel paths, with each path carrying 5A rms, you will be well within the primary conductor rating. In fact you could continuously run 25A continuous in the primary (8.3 A per path) without any risk to the device.

    As I said in another post, you could probably wire the primary current via a conductor threaded once through the 3.2mm hole in the transducer. Assuming you only want to measure 15A rms then provided the conductor can carry 15A rms continuous, then you would have the same measurement outcome as you would if you used the PCB connections as a 3-way parallel connection.

    If you want to measure more than 25A rms continuous then you can't use the PCB connections. You'd have to use the primary wire through the 3.2mm hole in the core option. There will be a limit on how much current the wire you insert through the core could carry - you would have to consult conductor data tables to determine the maximum current rating of the wire you choose. If you wired a solid bare copper conductor 3.2 mm diameter through the hole that would give the maximum current handling possibility. But you probably don't want the hazard of a bare conductor live at mains voltage. Better to use insulated wire. So the insulated conductor cross-sectional-area you could fit through the 3.2mm hole would be less than that of a 3.2mm diameter bare conductor.
     
  2. miloboy

    Thread Starter New Member

    Jun 1, 2010
    19
    0
    my measurement range will be from 0.5A-15A if , is that possible to measure such low current? and with the high sensitivity with maximum 15 A requirement ,is that able to use the configure with wire the primary with Np=3 which u mention b4 better sensitivity ?
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    790
    At the 15A continuous maximum range requirement you are constrained to have Np=1. That's a limitation which you have to live with if you use this particular transducer. It won't matter which device you choose because the dynamic range requirement will mean you will have similar sensitivity issues at the low measurement point. In the end it might mean you have to increase the number of data bits if you are applying A-D conversion after the signal is acquired.

    Again you don't have a particularly clear goal. Do you want to measure 0.5-15A ± 0.01A ? What error can you tolerate in your overall power measurement goal? You need to state what you require.

    As I indicated, you will be better served by writing a simple specification of what you expect the measurement system will do and then make the decisions about what components will satisfy your specification. It seems to me you aren't getting very far - primarily because you are too focused on the current transducer, which after all is only one component in the overall measurement chain.
     
  4. miloboy

    Thread Starter New Member

    Jun 1, 2010
    19
    0
    my tolerate can up to 10% , what shud i concern is small current detection.
     
  5. miloboy

    Thread Starter New Member

    Jun 1, 2010
    19
    0

    are u mind to explain more about it ? i am doubt with how to measure the power factor with different load appliances.. do you have any method , device or circuit to measure power factor?
     
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    203
    Measuring power factor is tricky, there's really no easy way to do it without an accurate ampmeter, voltmeter and wattmeter.
     
  7. miloboy

    Thread Starter New Member

    Jun 1, 2010
    19
    0
    i saw some IC to perform this .. but it sell with a big amount of unit ..sob
     
Loading...