ETS-Lindgren (EMCO) HI-3604 ELF Survey Meter

ETS-Lindgren's HI-3604 ELF Survey Meter is designed to evaluate both electric and magnetic fields associated with 50/60 Hz power lines, line-powered equipment and appliances. The HI-3604 Low Frequency Survey Meter provides the engineer, industrial hygienist and health and safety professional with a sophisticated tool for accurate investigation of power frequency environments.

The custom LCD display indicates electric fields in volts/meter and magnetic fields in gauss, tesla, or amperes/meter units. A bar-graph analog indicator aids in quickly locating maximum field orientations and “hot spots”. Full auto-ranging and a sealed membrane switch control panel make the HI-3604 ELF Survey meter ideal for field surveys. The on-board data logging feature allows up to 112 readings to be saved in internal memory storage.

The HI-3604 Power Frequency Field Strength Measurement System is designed to assist in the evaluation of electric and magnetic fields that are associated with 50/60 Hz electric power transmission and distribution lines along with electrically operated equipment and appliances. Direct digital readout of field strength is provided by the instrument with the ability to read the meter remotely via a fiber optic remote control (Model HI-3616) which is available as an option. The HI-3604 finds applications in research and environmental field studies where knowledge of the strength of power frequency fields is required. It is designed to provide engineers, industrial hygienists and health and safety personnel with a sophisticated tool for the accurate investigation of power frequency electrical environments.

The HI-3604 has two selectable sensors for measuring both electric and magnetic fields. The instruments' capabilities include data-logging, waveform output, full auto-ranging, and a custom Liquid Crystal Display (LCD) with a bar graph. All selection and control functions are input from a front panel membrane switch pad. True RMS (root-meansquare) detection assures accurate measurements of complex waveforms. The waveform output jack allows observation and evaluation of the actual waveform being measured. The data-logger feature captures up to 112 field readings for later review using front panel controls. Microprocessor technology is incorporated in the HI3604 to provide for automatic range changing (manual range changing may be selected) and automatic zeroing of the instrument.

Electric fields are detected by a displacement current sensor which consists of two thinly separated conductive disks which are connected together electrically. When immersed in an electric field, charge is redistributed among the two parallel disks such that the electric field between the two disks remains at zero. This redistribution of charge is reflected as a displacement current which can be measured and, subsequently, related to the external electric field strength. This type of transducer possesses a flat frequency response and permits accurate measurement of fields having significant harmonic content with energy at frequencies above the fundamental of 50 or 60 Hz.

Surrounding the circular displacement current sensing disks is a coil consisting of several hundred turns of fine gage wire. When placed in an alternating magnetic field, a current is induced in the coil which is proportional to the strength of the applied magnetic field. Magnetic field strength is then determined by measuring the voltage developed across the terminals of the coil. While an unterminated loop will provide an output which is directly proportional to the frequency of the magnetic field, the HI-3604 employs electronic compensation circuitry which results in a tailored frequency response that is flat in the frequency range of importance to power frequency measurements. This feature permits the HI-3604 to be used in environments having significant harmonic content and yield accurate measures of the resultant fields. Broadband response is required when measuring fields having significant harmonic distortion such as may occur with electrical machinery.