The B&K Precision 307A analog megohmmeter is an insulation tester with three test voltages—250, 500, and 1,000V—for measuring insulation resistance to 400MΩ to indicate the condition of windings or cables in motors, switchgears, electrical installations, and other insulated equipment, and it also measures low-resistance to 500Ω and AC voltage to 600V, lighting a warning indicator when a live circuit is detected. When a resistance measurement is complete and the test button is released, residual voltage is automatically discharged from the circuit under test. The test button can be locked for extended measurement sessions. Overload protection helps prevent damage to the meter. The meter is built into a carrying case and has a taut band movement for prompt, accurate readings. It is rated for category (CAT) III installations to 600V, which covers equipment in fixed installations, such as switches in the fixed installation and some industrial equipment that is permanently connected to the fixed installation. The unit has a low-battery indicator that signals when the batteries need to be replaced. It comes with eight 1.5V AA batteries, a set of test leads, a 0.5A, 250V fuse, and instructions. Megohmmeters are commonly used for electrical maintenance and testing in industries such as HVAC, transportation, manufacturing, mining, and utilities, among others.
|Maximum insulation resistance measured||400MΩ|
|Test voltages||250V, 500V, 1,000V|
|Maximum low-resistance measured||500Ω|
|Maximum AC voltage measured||600V|
|Installation rating||CAT III, 600V|
|Standards met||IEC safety standard 1010-1; CE marking|
|Power||(8) 1.5V AA batteries|
|Dimensions (H x W x D)*||180 x 220 x 90mm|
*H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.
Megohmmeters, also called insulation testers, are electrical test meters that measure resistance to the flow of current in an electrical component or circuit and check the continuity of an electrical circuit to detect electrical problems such as degraded insulation and improper circuit connections in equipment, wiring, and power supplies. Resistance is an indicator of the overall condition of the device being tested. Megohmmeters have an internal power supply, such as a battery or a capacitor, which supplies a test voltage to a circuit or component that is turned off. Test leads are connected in a series to the tester and the circuit or device being tested. The meter calculates the difference in voltage between the leads and measures the resistance. Most megohmmeters have two terminals for test lead attachment. The two-terminal, or two-wire, measurement method includes the resistance of the circuit or device being tested and the resistance of the test leads, and generally provides sufficient accuracy for measuring large values of resistance in insulation testing applications.
B&K Precision manufactures test and measurement instruments for research and development, production-line testing, and electronic field service applications. The company, founded in 1951, is headquartered in Yorba Linda, CA. It meets International Organization for Standardization (ISO) standard 9001:2008 and is compliant with Restriction of Hazardous Substances (RoHS) and waste electronic and electrical equipment (WEEE) directives.