Tipos De Sondas De Corriente
Páginas: 3 (631 palabras)
Publicado: 25 de enero de 2013
TYPES OF CURRENT PROBES
- DC Coupled
There are DC coupled probes whose response extends from DC to 50 MHz or higher. These probes usually use both Hall Effect sensors and conventional coilpickups with matched frequency response curves. These current probes can be affected by static electric fields. Such a sensitivity will appear to indicate a DC current flowing.
- AC Coupled
AC coupledcurrent probes typically use a magnetic core that encircles the current carrying conductor. A pickup coil is wound around this core and delivers the output signal. The hinged- donut type ofconstruction is popular. It is not necessary to cut or disconnect the conductor to be measured.
Current probes are characterized by Transfer Impedance , Z t , the ratio of output voltage to current flowingthrough the probe. The transfer impedance of the F- 33- 1 current probe has flat frequency response from several MHz to about 300 MHz.
MATCHED CURRENT PROBES
Most current probes have a Z taccuracy of +/- 2 dB. To make differential current measurements for EMC work or measurements of pulsed EMI currents (ESD/ EFT), it is necessary to have a pair of probes matched in amplitude response. The F-33- 1 probes we will be using are matched to within 1% to 2%.
CURRENT PROBE EQUIVALENT CIRCUIT
[pic]
|CURRENT PROBE RESPONSE |CURRENT PROBERESPONSE (cont.) |
|[pic] |[pic]|
EFFECT OF PROBE TERMINATIONS (parallel resistance)
[pic]
CURRENT PROBE RESPONSE (with parallel resistor on output)
[pic]
CORE LOSSES
The losses in a current probe’s core appearas a resistance in parallel across the output. This resistance becomes, in effect, part of the termination and needs to be taken into account in calculations.
The losses can be measured either by...
- DC Coupled
There are DC coupled probes whose response extends from DC to 50 MHz or higher. These probes usually use both Hall Effect sensors and conventional coilpickups with matched frequency response curves. These current probes can be affected by static electric fields. Such a sensitivity will appear to indicate a DC current flowing.
- AC Coupled
AC coupledcurrent probes typically use a magnetic core that encircles the current carrying conductor. A pickup coil is wound around this core and delivers the output signal. The hinged- donut type ofconstruction is popular. It is not necessary to cut or disconnect the conductor to be measured.
Current probes are characterized by Transfer Impedance , Z t , the ratio of output voltage to current flowingthrough the probe. The transfer impedance of the F- 33- 1 current probe has flat frequency response from several MHz to about 300 MHz.
MATCHED CURRENT PROBES
Most current probes have a Z taccuracy of +/- 2 dB. To make differential current measurements for EMC work or measurements of pulsed EMI currents (ESD/ EFT), it is necessary to have a pair of probes matched in amplitude response. The F-33- 1 probes we will be using are matched to within 1% to 2%.
CURRENT PROBE EQUIVALENT CIRCUIT
[pic]
|CURRENT PROBE RESPONSE |CURRENT PROBERESPONSE (cont.) |
|[pic] |[pic]|
EFFECT OF PROBE TERMINATIONS (parallel resistance)
[pic]
CURRENT PROBE RESPONSE (with parallel resistor on output)
[pic]
CORE LOSSES
The losses in a current probe’s core appearas a resistance in parallel across the output. This resistance becomes, in effect, part of the termination and needs to be taken into account in calculations.
The losses can be measured either by...
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