BK Precision 391A [391A] 4 1/2, 20,000 Count Test Bench Digital Multimeter

The BK Precision 391A digital multimeter (also known as a multitester) is a true RMS, manual-ranging meter for measuring current, voltage, resistance, and frequency in electrical testing applications. The meter comes with a set of detachable test leads. The logic test reports the logic state of an electronic circuit. An audible continuity sensor confirms a circuit conducts electricity, and a diode test detects proper functioning of a circuit’s diodes. The meter measures duty cycles to 90%, indicating the percent of time a circuit is on. The microamp function identifies current changes in flame detector applications. A hold function keeps a reading on the display, even after the meter has been disconnected. An alarm sounds when the test leads are connected to the wrong jack for the measurement being taken. The unit automatically turns off after 45 minutes of nonuse to conserve battery life, and a low-battery indicator signals when the meter's batteries need to be replaced. The meter's body is made of molded rubber, which helps protect it against damage from falls, impacts, and abrasion. The meter has a built-in tilt stand for propping on a flat surface, and a hanging strap is included for hands-free use.

This true RMS (root mean square) meter provides accurate readings when measuring linear loads, such as standard induction motors and incandescent lights, where the current or voltage has an undistorted waveform, or nonlinear loads, such as electronic devices or motors, where the current or voltage has a distorted waveform. It is a manual-ranging meter that requires the operator to choose the appropriate operating range for the property being measured. The LCD has a 20,000-count resolution, meaning it can display up to 19,999 units (4-1/2 digits) before the operating range needs to be changed. It meets International Electrotechnical Commission (IEC) safety standard 61010 and is certified for Category III installations up to 1,000V, which covers items used with enclosed building circuit installations (such as service panel parts, branch circuits, and fixed installations that are connected directly to a building's AC power supply).