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Terms Definition Reference
AC (Alternating Current) In alternating current (AC), the movement of electric charge periodically reverses direction. The usual waveform of an AC power circuit is a sine wave. Certain applications use different waveforms, such as triangular or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current.
Autoranging Automatic switching of a multirange meter from its lowest to the next higher range, with the switching process repeated until a range is reached for which the full-scale value is not exceeded.
Cable Tracker When you are making a hole in the wall for installation of an air conditioner or on the floor for installation of a machine, or excavating a road, you have to know the layout of the cables, water pipelines or gas pipelines in the wall or ground to keep away from these facilities and avoid un- necessary troubles and even dangers. In the past, there is only one solution for this issue, that is, to find the construction drawings of these embedded facilities. However, in most cases, these drawings cannot be found and you have to take your chance, which may result in interruption of cables or pipelines, bringing about the danger of power failure, electric shock, explosion or threat to life. Now, with this MS6818 Cable Locator developed by our company to effectively assist users to locate and detect cables, you no longer need to take your chance.
Capacitance ( C ) Capacitance is the ability of a component or circuit to collect and store energy in the form of an electrical charge. The SI unit of capacitance is the farad (symbol: F), named after the English physicist Michael Faraday. A farad capacitor, when charged with 1 coulomb of electrical charge, has a potential difference of 1 volt between its plates.
CE certification CE Marking is the symbol as shown on the top of this page. The letters "CE" are the abbreviation of French phrase "Conformité Européene" which literally means "European Conformity". CE Marking on a product is a manufacturer's declaration that the product complies with the essential requirements of the relevant European health, safety and environmental protection legislation, in practice by many of the so-called Product Directives. *Product Directives contains the "essential requirements" and/or "performance levels" and "Harmonized Standards" to which the products must conform. Harmonized Standards are the technical specifications (European Standards or Harmonization Documents) which are established by several European standards agencies (CEN, CENELEC, etc).
Clamp meter (DCM) In electrical and electronic engineering, a current clamp or current probe is an electrical device having two jaws which open to allow clamping around an electrical conductor. This allows properties of the electric current in the conductor to be measured, without having to make physical contact with it or to disconnect it for insertion through the probe. Current clamps are usually used to read the magnitude of a sinusoidal current, but in conjunction with more advanced instrumentation, the phase and waveform are available. Very high alternating currents (1000 A and more) are easily read with an appropriate meter; direct currents and very low AC currents (milliamperes) are more difficult to measure
Continuity In electronics, a continuity test is the checking of an electric circuit to see if current flows . A continuity test is performed by placing a small voltage across the chosen path. If electron flow is inhibited by broken conductors, damaged components, or excessive resistance, the circuit is "open".
Current ( I ) An electric current is a flow of electric charge. The common symbol for current is the uppercase letter I. The SI unit for measuring an electric current is the ampere(A), which is the flow of electric charge across a surface at the rate of one coulomb per second. The particles that carry the charge in an electric current are called charge carriers.
DC (Direct Current) Direct current (DC) is the unidirectional flow of electric charge. Direct current is produced by sources such as batteries, thermocouples, solar cells, and commutator-type electric machines of the dynamo type.
Diode A diode is a specialized electronic component with two electrodes called the anode and the cathode. Most diodes are made with semiconductor materials such as silicon, germanium, or selenium. The fundamental property of a diode is its tendency to conduct electric current in only one direction. When the cathode is negatively charged relative to the anode at a voltage greater than a certain minimum called forward breakover, then current flows through the diode. If the cathode is positive with respect to the anode, is at the same voltage as the anode, or is negative by an amount less than the forward breakover voltage, then the diode does not conduct current. This is a simplistic view, but is true for diodes operating as rectifiers, switches, and limiters. The forward breakover voltage is approximately six tenths of a volt (0.6 V) for silicon devices, 0.3 V for germanium devices, and 1 V for selenium devices.
Display Counts Status of accuracy and resolution,the higher the more accurate
Duty Cycle Duty cycle is the proportion of time during which a component, device, or system is operated. The duty cycle can be expressed as a ratio or as a percentage. Suppose a disk drive operates for 1 second, then is shut off for 99 seconds, then is run for 1 second again, and so on. The drive runs for one out of 100 seconds or 1/100 of the time, and its duty cycle is therefore 1/100, or 1 percent.
Emissivity All objects at temperatures above absolute zero emit thermal radiation. However, for any particular wavelength and temperature the amount of thermal radiation emitted depends on the emissivity of the object's surface. The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Emissivity can have a value from 0 (shiny mirror) to 1.0 (blackbody). Most organic, painted, or oxidized surfaces have emissivity values close to 0.95
ETL certicfication Most areas in the United States, the approval of electrical products is compulsory. Certification marks – demonstrate compliance to the requirements of widely accepted product safety standards, as determined through independent testing and periodic follow-up inspections by an NRTL.
Frequency Frequency describes the number of crests of a wave that move past a given point in a given unit of time. The most common unit of frequency is the hertz (Hz ), corresponding to one crest per second. The frequency of a wave can be calculated by dividing the speed of the wave by the wavelength.So if the time it takes for a wave to pass is is 1/2 second, the frequency is 2 per second. If it takes 1/100 of an hour, the frequency is 100 per hour.
GFCI Ground Fault Circuit Interrupter is a device that shuts off an electric power circuit when it detects that current is flowing along an unintended path, such as through water or a person. It is used to reduce the risk of electric shock, which can cause the heart to stop or cause burns. They can also prevent some fires, like when a live wire touches a metal conduit. Trip Current :4~6mA (for standard) Trip Time :25ms (for standard)
Ghost Voltage Ghost voltage can occur when power supply conductors and adjacent unused conductors create a capacitive coupling between conductors.
Inductor (L) An inductor , also called a coil or reactor, is a passive two-terminal electrical component that stores electrical energy in a magnetic field when electric current is flowing through it. An inductor typically consists of an electric conductor, such as a wire, that is wound into a coil. When the current flowing through an inductor changes, the time-varying magnetic field induces a voltage in the conductor, described by Faraday's law of induction. In the SI, the unit of inductance is the henry (H). Inductors have values that typically range from 1 µH (10−6H) to 1 H.
Inrush Current When electrical equipment is first turned on,a large current flows that exceeds the steady-state current value. This current is called an inrush current.
IR-T An infrared thermometer is a thermometer which infers temperature from a portion of the thermal radiation sometimes called blackbody radiation emitted by the object being measured. They are sometimes called laser thermometers as a laser is used to help aim the thermometer, or non-contact thermometers or temperature guns, to describe the device's ability to measure temperature from a distance. By knowing the amount of infrared energy emitted by the object and its emissivity, the object's temperature can often be determined.
Low-Z (Dual Impedance Characteristics) Normal impedance(10M) with normal testing capabilities. Low impedance Lo-Z for testing where “ ghost voltage” may be present. lf this possibility exists,or when testing for the presence of voltage,use the Lo-Z mode to switch to the low impedance setting to remove the ghost voltages during measurement.
LPF Low-pass filter is a filter that passes signals with a frequency lower than a certain cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency.
M Mega-(symbol M) is a unit prefix in the metric system denoting multiplication by one million
Multimeter (DMM) A multimeter or a multitester, also known as a VOM (Volt-Ohm-Milliammeter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter can measure voltage, current, and resistance. A multimeter can be a hand-held device useful for basic fault finding and field service work, or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices
NCV Non contact voltage, NCV tester is a useful tool for any kind of electrical work—there’s no quicker or simpler way to safely check for electrical current in a wire, outlet, switch, or an old lamp that has mysteriously stopped working.
NFB No Fuse Breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overcurrent or overload or short circuit. Its basic function is to interrupt current flow after protective relays detect a fault.
RCD Residual Current Device is a device that shuts off an electric power circuit when it detects that current is flowing along an unintended path, such as through water or a person. It is used to reduce the risk of electric shock, which can cause the heart to stop or cause burns. They can also prevent some fires, like when a live wire touches a metal conduit. Trip Current :5~30mA (for standard) Trip Time :25~40ms (for standard)
Relative Humidity (%RH) The ratio of the actual amount of water vapor present in the air at a given temperature to the maximum amount that the air could hold at that temperature. Relative humidity is expressed as a percentage. From 0% which indicates the air is absolutely dry to 100% which indicates the air is saturated.
Resistance ( R ) Resistance is the opposition that a substance offers to the flow of electric current. It is represented by the uppercase letter R. The standard unit of resistance is the ohm(Ω)
RoHS RoHS stands for Restriction of Hazardous Substances. RoHS, also known as Directive 2002/95/EC, originated in the European Union and restricts the use of specific hazardous materials found in electrical and electronic products. All applicable products in the EU market after July 1, 2006 must pass RoHS compliance. The substances banned under RoHS are lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (CrVI), polybrominated biphenyls (PBB), polybrominated diphenyl ethers (PBDE), and four different phthalates (DEHP, BBP, BBP, DIBP).
Safety Rating Category I is for measurements performed on circuits not directly connected to MAINS.Examples are measurements on circuits not derived from MAINS and specially protected (internal) MAINS-derived circuits. Category II is for measurements performed on circuits directly connected to the low voltage installation.Examples are measurements on household appliances, portable tools, and similar equipment. Category III is for measurements performed in the building installation.Examples are measurements on distribution boards, circuit-breakers, wiring, including cables, bus-bars, junction boxes, switches, socket-outlets in the fixed installation, and equipment for industrial. Category IV is for measurements performed at the source of the low-voltage installation.Examples are electricity meters and measurements on primary overcurrent protection devices and ripple control units.
Thermocouple A thermocouple is an electrical device consisting of two dissimilar conductors forming electrical junctions at differing temperatures. A thermocouple produces a temperature-dependent voltage as a result of the thermoelectric effect, and this voltage can be interpreted to measure temperature. Thermocouples are a widely used type of temperature sensor
True RMS RMS (Root Mean Square) true-rms meter can accurately measure both pure waves and the more complex nonsinusoidal waves. The normal alternating current mains power supply comprises a sinusoidal waveform that has symmetrical positive and negative half cycles. The RMS (Root Mean Square) value of an alternating current is measured in terms of the direct (dc) current that produces the same heating effect in the same resistance. Problems can arise when the mains waveform becomes distorted because of the effects of certain types of loads. Thyristor and triac drives, switched mode power supplies, etc, create harmonics of the main waveform because they take ‘gulps’ of current during a cycle. This results in a non-sinusoidal waveform. Low cost measuring instruments assume that ac waveforms are sinusoidal and can thus give false readings. Typically in a waveform with a high CREST FACTOR i.e. a high peak current, a low cost instrument will only measure the average current and thus give a low reading. This can result in cables, fuses and breakers being sized too low. When measuring electricity consumption it will also result in a low reading.
Voltage ( V ) Voltage(symbol: V), also called electromotive force, is a quantitative expression of the potential difference in charge between two points in an electrical field.
μ Micro- (symbol μ) is a unit prefix in the metric system denoting a factor of one millionth
hFE transistor Transistor-check function. hFE of a transistor is the current gain or amplification factor of a transistor.
k Kilo- (symbol k) is a unit prefix in the metric system denoting multiplication by one thousand.
m Milli- (symbol m) is a unit prefix in the metric system denoting a factor of one thousandth