This “phantom voltage” is due to capacitive coupling between wire 5 and wire 8 (still energized) throughout the length of their mutual paths within the conduit. With the power switch feeding wire 5 in the open state, there should be no AC voltage measured between wire 5 and neutral (L2), yet the voltmeter registers slightly over 10 volts AC. However, in industrial applications, this high input impedance may cause the meter to register the presence of voltage where none should rightfully appear.Ĭonsider the case of testing for the absence of AC voltage on an isolated power conductor that happens to lie near other (energized) AC power conductors within a long run of conduit: This is commendable, as an ideal voltmeter should have infinite input impedance (so as to not “load” the voltage signal it measures). Most digital multimeters exhibit very high input impedance in their voltage-measuring modes. My first “trick” is not a feature of a high-quality DMM so much as it is a solution to a common problem caused by the use of a high-quality DMM. If your tool budget can support a digital multimeter with “logging” capability, spend the extra money and take the time to learn how this feature works! Avoiding “phantom” voltage readings More advanced multimeters actually log the time when an event occurs, which is obviously a more useful feature. The most basic high-low capture function on a multimeter only tells you what the highest and lowest measured readings were during the test interval (and that only within the meter’s scan time – it is possible for a very brief transient signal to go undetected by the meter if its duration is less than the meter’s scan time). Many times I have used this feature to monitor a signal with an intermittent “glitch,” while I attended to other tasks. This feature is extremely useful when diagnosing intermittent problems, where the relevant voltages or currents indicating or causing the problem are not persistent, but rather come and go. On Fluke brand multimeters, this is called the Min/Max function. Many modern multimeters have a feature that records the highest and lowest measurements sensed during the duration of a test. The ability of these multimeters to accurately measure true RMS amplitude, discriminate between AC and DC signals, measure AC signals over a wide frequency range, and survive abuse both mechanical and electrical, is outstanding.
#Multi meeter professional
I am personally a great fan of Fluke brand meters, having used this particular brand for nearly my whole professional career.
![multi meeter multi meeter](https://imgaz2.staticbg.com/thumb/large/oaupload/banggood/images/A8/02/5a17ff98-6304-4e94-a4c4-f4a26f2df3c4.jpg)
![multi meeter multi meeter](http://www.valuetesters.com/assets/images/media/catalog/product/e/x/ex330_1500x1500.jpg)
#Multi meeter how to
The subject of this section is how to use a digital multimeter for some of these advanced tests.įor all these tests, I suggest the use of a top-quality field multimeter. Not only is a good-quality multimeter capable of precisely indicating electrical voltage, current, and resistance, but it is also useful for more advanced tests. This one piece of test equipment, properly wielded, yields valuable insight into the status and operation of many electrical and electronic systems. The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s collection.