Extech Instruments announces its MA640 600A True RMS AC/DC Clamp Meters + NCV that has a higher accuracy rating then standard RMS meters. To use a clamp meter, only one conductor is normally passed through the probe. If more than one conductor were to be passed through, then no current will be measured at all because the current flowing in one direction will cancel the one flowing in the other direction.
Standard RMS clamp meters carry out measurement by averaging these readings and applying a correction factor, producing a result that is very inaccurate. The MA6490's True RMS is designed with a more precise calculation process that provides a correct measurement of all current and gives a true accuracy reading.
The MA640 works by connecting an electrical meter with an integral current clamp. The meter contains a mechanical pointer-locking device so that the current reading can be taken at various points. This allows the reading to be taken even at location where the pointer can't be seen. If this is the case, the pointer locks and the meter can then be brought out to a convenient place for the reading while maintaining an accurate data read for that hidden location.
The MA640 features a built in non-contact voltage detector with LED alert and a 6000 count, backlit LCD display. Its 1.5" (40mm) jaw size is versatile for various conductor sizes of up to 500MCM. Multi-meter functions include AC Current, AC/DC Voltage, Resistance, Capacitance, Frequency, Temperature, Duty Cycle, Diode, and Continuity. This model is also able to measure DC current and includes convenience settings which can be set at Relative Mode for Capacitance Zero and Offset Adjustment, as well as data hold and min/max and auto power off.
The MA640 comes complete with test leads, Type K bead wire temperature probe, 9V battery and carrying case.