The Extech MA640 clamp meter is compact and easy to hold. Whether you are performing amp readings in a heavy-duty industrial setting or doing commercial electrical work, the 600A rating and ample 40mm jaw opening can accommodate most jobs, swallowing conductors up to 750 MCM. The large, illuminated, dual display is useful in poorly lit job sites, and the 4-digit (6,000 count) readout is complemented by a bargraph display to simulate an analog display. You can operate the meter with one hand, having a thumb-dial selector that is ergonomically placed off the side of the meter. The heart of the MA640 is an advanced digital multimeter. You can select auto- or manual-ranging and measurement functions cover all types of troubleshooting over and above noninvasive current probe measurements: voltage, resistance, capacitance, frequency, duty cycle, diode and continuity tests. Even measure temperature with the supplied Type K bead wire probe. Users can also select one of several one-button functions: press HOLD to freeze a reading on the LCD; MAX/MIN tracks and displays maximum and minimum values (useful for blind measurements); and REL activates Relative mode for “zeroing out” the meter, useful for improving the accuracy of DC current measurements.
True RMS Compensates for Distortion from Electronic Devices It can be very difficult to make accurate current and voltage readings in industrial and commercial applications when electronic devices are present. Fluorescent lights, motor drives, computer power supplies, and other electronic systems can distort the AC waveform, making it hard for averaging meters to get an accurate read. True RMS uses a more advanced formula to adjust for this kind of distortion. One important safety tool that is built in to the MA640 is a non-contact voltage (NCV) detector, which quickly detects the presence of voltage on live wires and alerts users with a red LED indicator.