Coil Resistance and Reactance Time Series

Citation Author(s):
Noel
Jameson
Submitted by:
Noel Jameson
Last updated:
Fri, 01/18/2019 - 11:37
DOI:
10.21227/3y5k-xq26
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Abstract 

A solenoid-operated valve with DC resistance of about 10.3 Ω was exposed to 50 % RH, its rated temperature of 80 °C, and powered at its rated voltage of 12 VDC. (Note: the valve was unrated with regards to relative humidity, RH.) Using Fourier transform infrared (FTIR) spectroscopy, the insulation material was found to be a combination of polystyrene and polyethylene terephthalate. The wire gauge was not disclosed in the valve information sheet. The conductor diameter was measured to be about 380 μm and the insulation thickness was measured to be about 27 μm, hence, the magnet wire size was determined to be AWG (American wire gauge) 26.5. Once every 48 hours, the valve was removed from the chamber to perform impedance measurements. The coil was at an elevated temperature when removed from the chamber, so, in order to achieve approximately isothermal impedance measurements, the settling of coil DC resistance to a constant value was used to indicate when the coil had cooled to room temperature (between 22 °C and 26 °C). Using an Agilent 16047E four-terminal fixture, the coil was connected to an Agilent E4980A LCR meter, which can measure impedance at frequencies ranging from 20 Hz to 2MHz. The LCR meter measured coil impedance at frequencies over the entire operational range of the LCR meter, with an RMS voltage of 500 mV.

Instructions: 

The variables are:

R_avg: the average of three (3) measurements of the real part of impedance (resistance) at 501 individual frequencies ranging from 20 Hz to 2 MHz. Each column is a single spectrum, making each row a time series at one frequency. There are sixty-four (64) impedance spectra. The first 41 were taken prior to the coil insulation failure.

 

rH: the measurements of the real part of impedance (resistance) taken prior to insulation failure. These are the first 41 columns of R_avg and the matrix has the same form as that of R_avg.

 

X_avg: the average of three (3) measurements of the imaginary part of impedance (reactance) at 501 individual frequencies ranging from 20 Hz to 2 MHz. Each column is a single spectrum, making each row a time series at one frequency. There are sixty-four (64) impedance spectra. The first 41 were taken prior to the coil insulation failure.

 

xH: the measurements of the imaginary part of impedance (reactance) taken prior to insulation failure. These are the first 41 columns of X_avg and the matrix has the same form as that of X_avg.

 

f: the frequencies at which impedance was measured. There are 501 entries in this vector

 

Zmag_avg: the average of three (3) measurements of impedance magnitude at 501 individual frequencies ranging from 20 Hz to 2 MHz. Each column is a single spectrum, making each row a time series at one frequency. There are sixty-four (64) impedance spectra. The first 41 were taken prior to the coil insulation failure.

 

Zpha_avg: the average of three (3) measurements of impedance phase at 501 individual frequencies ranging from 20 Hz to 2 MHz. Each column is a single spectrum, making each row a time series at one frequency. There are sixty-four (64) impedance spectra. The first 41 were taken prior to the coil insulation failure.

 

T: the times at which impedance measurements were taken, starting at zero (0). There are 64 times in this vector.

 

t: the first 41 measurement times taken prior to insuation failure