ETS-Lindgren HI-3637 VLF Magnetic Field Meter - Manual (Page 9)

HI n 3637 Manual Page — 1
1.0 DESCRIPTION
Introduction
The HI n 3637 VLF (very-low frequency) Magnetic Field
Meter measures magnetic field flux density in the
frequency range of 2 kHz to 400 kHz. The capabilities of
this instrument are designed to conform to the guidelines
issued recently in Sweden—as well as the IEEE P-1140
protocol—for measuring VLF magnetic fields produced by
video display terminals (VDTs). Applications for this
versatile meter range from VDTs and computer monitors
to high current factory locations.
The HI n 3637 is a self-contained three-axis flux density
meter designed to respond to either sinusoidal or complex
magnetic field waveforms, such as those produced by the
vertical deflection system of a VDT. The meter circuit
utilizes a microprocessor to continually compute the root-
mean-square (RMS) value of magnetic field flux density
and display it directly on an analog meter, allowing quick
assessment of the actual flux density value. The size of
the instrumentation/readout package was chosen for two
reasons. The first is to allow for two layers of electric and
magnetic shielding in addition to the outer housing. The
second is to allow for hand held operation. This
portability makes the HI n 3637 particularly useful in
surveying the magnetic field flux density distribution over
a large area in a short amount of time.
The probe sensor array consists of three mutually
orthogonal multi-turn loops connected to the
instrumentation/readout package via a 1.5 meter cable.
Readings are independent of probe orientation. The
probe is electrically shielded, making the HI n 3637
immune to most electric field effects.
The HI n 3637 has a wide dynamic measurement range:
4 nT to 400 : T (100 dB). This makes the HI n 3637
convenient for finding VLF magnetic field distributions in
any application. The supplied alternate panel label
converts the meter scale to Gauss (0.04 mG to 4 G).