High Frequency/High Field EMDEX II Specifications

Transcription

1 High Frequency/High Field EMDEX II Specifications Enertech Consultants Campbell, California

2 Legal Notice The EMDEX exposure system, including hardware, EMCALC 2000 software and documentation, was prepared by Enertech Consultants of Santa Clara County, Inc. Neither Enertech nor any person acting on its behalf: (a) makes any warranty, expressed or implied, with respect to the use of any information, apparatus, method, or process disclosed in this exposure system or that such use may not infringe privately owned rights; or (b) assumes any liabilities with respect to the use of, or for damages resulting from use of, any information, apparatus, method, or process disclosed in this exposure system. The non-transferable and non-exclusive program license granted by Enertech to purchasers of this exposure system and software package may not be assigned, sublicensed, or otherwise transferred without written consent from Enertech. No right to print or copy, in whole or part, the licensed programs or documentation is granted except for back-up purposes or for archive purposes. The licensee agrees not to provide or otherwise make available any licensed program or documentation to any person other than licensee. 2

3 High Frequency/High Field EMDEX II Hardware Specifications Overall Dimensions 6.6" x 2.6" x 1.5" (16.8 x 6.6 x 3.8 cm) Weight (without battery) 10 ounces (784 g) Operating Temperature F (0-60 C) Operating Humidity 0-95% Power Operational Modes Data Types On-board Computer Memory A/D Resolution Sampling Intervals Sensors AUX Jack REMOTE Jack Frequency Bandwidth 9-volt alkaline or lithium battery Normal (sample data stored in memory) Survey (Display data values only) Magnetic Field RMS resultant Broadband Magnetic Field RMS resultant Harmonic Equivalent Electric Field RMS Current Tattletale Model V with 5X1 expansion 156 Kb CMOS-RAM (512 Kb Memory Expansion Available) 0.1% at full scale (10 bit resolution) Maximum 1 sample per 1.5 seconds Minimum - 1 sample per 327 seconds Three (3) orthogonally oriented magnetic field sensor coils Designed to accept a signal from an external electric field or other special sensor. Maximum input current: 0.99 ma Designed to send a low-to-high transition to the signal counter of the Model V computer when the input resistance raises from below 100Ω to above 1000Ω. Broadband: Hz Harmonic: Hz 3

4 Frequency Response Low Frequency Field Rejection Total Harmonic Distortion Measurement calibration frequency 50/60 Hz Measurement Method Temperature Errors Broadband : Total variation of ±30% over entire range Harmonic : 100 Hz: +10% to -45% 120 Hz: +25% to -30% 150 Hz: +25% to -0% Hz: +25% to -25% 10 Hz signal: Greater than 1000 to 1 2 Hz signal: Greater than 10 6 to 1 Measurements of THD down to 3% distortion Typical Accuracy ±2% True RMS Measurement (with Crest Factor) Crest Factor Error : Crest Factor 2:1 Additional ±2% Crest Factor 3:1 Additional ±5% Note: The Crest Factor of a periodic signal is the ratio of its crest (peak, maximum) to its root-mean-square (RMS) value. Readings will vary no more than ±2% per 10 C change of temperature in the range of 0 C to 50 C. 4

5 High Frequency/High Field EMDEX II Magnetic Field Range Scale Range (mg) ,120 5, ,000 Resolution (mg) For range 0, the resolution is 0.5 mg but values are rounded to the nearest multiple of 4 mg. 5

6 High Frequency/High Field EMDEX II Electric Field Range Scale Full Scale (µa) Resolution (µa) Electric field ranges are given in microamps (µa) of injected 60 Hz current. Each electric field sensor will have a calibration constant in µa per 1 kv/m electric field. For example, the 60 Hz E-Probe has a constant of µa/v/m. 6

7 EMDEX II Frequency Response Frequency response is defined as the change in response of the EMDEX II to signals of different frequencies. Frequency response can be thought of as the sensitivity of the meter to signals within a certain frequency range. The EMDEX II is calibrated to measure 60 or 50 Hz electric and magnetic fields using two software selectable frequency bands: Broadband ranging from Hz, and Harmonic, which is sensitive to Hz fields. The strongest power frequency magnetic and electric fields are typically at the main transmission frequency of 50 or 60 Hz (called the fundamental). Harmonic signals can occur at integral multiples of the fundamental. For example, a fundamental at 60 Hz has harmonics at 120 Hz, 180 Hz, 240 Hz, and so on. A field with strong harmonic components will show strengths in the harmonic band almost as high as broadband. If the fundamental frequency is predominant, the harmonic band will have low readings relative to the broadband. The 50 or 60 Hz fundamental is not directly measured by the EMDEX II but is calculated from the harmonic and broadband measurements. If a field is dominated by harmonic frequencies, the value calculated for the fundamental frequency by EMCALC may be in error by a significant amount. See Appendix A in the EMCALC 2000 User Manual, for a detailed discussion of the Fundamental Calculation Check. 7

8 High Frequency/High Field EMDEX II Broadband Frequency Response ( Hz) Magnetic fields in the frequency band from Hz measure within ±30% of the fundamental frequency fields (50 or 60 Hz). Frequencies below 40 Hz are strongly attenuated and frequencies above 1000 Hz are attenuated proportional to the frequency (see figure below). High Frequency/High Field Emdex II 1.4 Normalized Magnetic Flux Density Frequency (Hz) 8