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Last Post 10/21/2011 11:34 AM by  Tony Hodges
CR series current transformer bandwidth
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Matthew Beasley
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10/19/2011 6:44 PM
    We are looking at an application where we would like to monitor the line frequency harmonics. The fundamental signal would be at 50Hz or 60Hz, but we are interested in the frequency response up to 3kHz. How much phase and amplitude error is there at 3kHz?
    Tony Hodges
    CRM Staff
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    10/20/2011 10:13 AM
    Dear Sir,

    Typically CT phase angle error will be consistent or improve with frequency provided the CT is not forced into saturation. For 50/60/400 Hz applications in the general purpose and revenue grade parts, frequencies up to 2 Khz will be within stated accuracies. Due to the lamination design, above 2Khz will typically cause a reduction in the magnetic saturation of the part.

    For this application, we recommend using a nickel core device at as low a voltage output as possible. The nickel core units that we manufacture utilize thinner laminations than the general purpose silicon steel cores, and will exhibit less loss of voltage capability at 3 Khz. By using the devices below this saturation point, you should be able to get the same specifications at 3Khz that you would at the 50/60/400 Hz levels.

    We can assist you in selecting the proper part if you can let us know the input current and the output voltage you are looking for.
    Matthew Beasley
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    New Member
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    10/20/2011 4:12 PM
    Thank you Tony,

    We are looking at the CR2 in ratios of 50:0.1, 100:0.1, 200:0.1 and 300:0.1. In all cases the burden resistor would be 4 ohms. More than 80% of the amplitude would be at 300Hz and less than 1% of the total amplitude would be above 2kHz.
    Tony Hodges
    CRM Staff
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    Basic Member
    Posts:154


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    10/21/2011 11:34 AM
    Dear Sir,

    Our CR2 Series has a silicone steel core and will not work above 2kHz. In order to work above 2kHz we will need to use a nickel core.
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