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Basics of Electricity Measurement Basics Accuracy & Calibration

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Basics of Electricity Measurement Basics Accuracy & Calibration Basics of Electrical Testing www.hioki.com Basics of Electricity Measurement Basics Accuracy & Calibration Electricity in Terms of Water Flow Measurement Category 1 Voltage Testing Resistance Testing Insulation Resistance Testing 4 How to Calculate Accuracy 1 Primary electrical circuits in equipment connected to an AC• electrical outlet by a • • Electricity can be likened to the flow of water. Connect to the circuit in parallel. Always conduct zero adjustment when measuring resistance. (Mechanical and Current CAT II power cord Measurement principle Digital Measuring Instruments Input impedance : low Input impedance : high electrical zero adjustment) Situations where voltage is being applied is hazardous Ohm’s Law Voltage = Current × Resistance High + Primary electrical circuits of heavy equipment (fixed installations) connected Analog Digital Switch from the transmission circuit, boost with a transformer to apply a high The accuracy and tolerance described in the product Instrument loss : large Instrument loss : small so separation is critical. specifications are given in terms of rdg., f.s., and dgt. CAT III directly to the distribution panel, and feeders from the distribution panel to outlets Max. voltage, then measure the current and convert it to a resistance value. Measurement uncertainty is often defined, and the uncertainty 300.0 V range BAT Electric External noise : low susceptibility External noise : high susceptibility displayed Potential The circuit from the service drop to the service entrance, and to the power meter Resistance measurement circuit of an analog meter Measurement terminal voltage characteristics (Hioki IR4000 series) limit is obtained from these values. MEASURE value Voltage Voltage EARTH A B A CAT IV and primary overcurrent protection device (distribution panel) SW 1,200 (1) f.s. (full scale: maximum displayed value, maximum scale, scale length) Low − drop drop Boost Resistance under test 1000V & Smoothing & Always separate Rectification 8 8 8 8 OFF V 1,000 Measured current Large current Small Generally, f.s. represents the range value currently used, and Large Based on the IEC61010-1 international standard concerning Small detection Digital ON V → I value Difference Current (I) the safety requirements for electrical equipment for 800 for analog displays, the maximum deflection of the needle. display Select HV in water level measurement, control, and laboratory use Vr Vr Zero range I2 600 (2) rdg. (reading: read value, displayed value, indicated value) Measuring 100V on the 300 V range LR6 x 4 (DC Voltage) 500V Drop connection Adjustment B When reading an instrument's specifications, a Distribution Distribution Rx Refers to the value actually being measured, i.e., the value that Water will not flow. Service drop panel panel A/D I1 400 voltage value will follow the measurement category, Fixed R value 250V is currently indicated or displayed by the measuring instrument. Water Voltage (V) Resistance (R) Power meter installation 200 Outlet Outlet display LINE 125V Resolution such as in “CATIII 600V” . Transformer flow Current 100 50V (3) dgt. (digit: resolution) This means that the instrument can measure up to detection Oscillating 0 25V Refers to the least significant digit of the digital display, i.e., the Oscillating 0 0.025 0.05 0.1 0.125 0.25 0.5 1 20 100 2,000 600V in a CAT III environment. control Measurement terminal voltage [V] ∞ lowest digit in the displayed value, located at the far right of a circuit circuit 0.1 V is the least significant digit Tester Equipment under test Measured resistance [MΩ] string. in the 300.0 V range What is DC ? Measurement Category and Rated Voltage Current Testing Low Resistance Testing• 1 Earth Resistance Testing• 1 How to Calculate Accuracy• 2 DC (Direct Current) is the flow of electric charge in one direction. to Ground Indication Direct wiring Serial connection to circuit Clamp Serial connection to circuit In order to measure without effects from wiring or contact resistance, What is earthing? Example 1: Measuring voltage using the Hioki 3281 Clamp Meter method Power line must be cut method No need to cut power line use the 4-wire measurement method in place of the 2-wire method Accuracy specifications: ±1.0%rdg.±3dgt. (300V range) Earthing refers to the work of connecting the electric path to the ground. The ground is a Measurement range: 300.0V stable potential, made possible by connecting the ground to an electric circuit. Earthing plays 2-wire method 4-wire method Measured value: 100V + many roles, such as securing the outer case of equipment, the neutral point of an electric (A) Reading uncertainty: ±1.0% of 100.0V → 99.0 to 101.0V CAT IV 600 V / CAT III 1000 V circuit, and the reference potential of electronic or communication devices. (B) Digit uncertainty: ±3dgt. → ±0.3V Constant Constant Measuring in the 0 current power current power Total uncertainty limits (range of true value) (A+B) = 98.7V to 101.3V 300.0 V range Main objectives Voltmeter I Voltmeter I Example 2: Measuring voltage using the Hioki 3169 Clamp On Power Meter - I I I I I The Hioki DT4280 Series is designed • Telecommunication and electronic equipment: to countermeasure electromagnetic waves, current current with a terminal shutter system to noise, and communication issues Accuracy specifications: ±0.2%rdg.±0.1%f.s. (voltage range) Measurement range: 300.0V • Building electrical equipment: to prevent electric shock prevent erroneous connections. Measured value: 100V Displayed r1 r2 r1 r3 r4 r2 • Lightning protection E E (A) Reading uncertainty: ±0.2% of 100.0V → 99.8 to 100.2V measured value Example DC Waveforms • Balance of potential Minute current direction Load current direction (B) Full scale uncertainty: ±0.1 f.s. → ±0.3V (300V x 0.001) Direct Ripple Pulsating Resistance Ro Resistance Ro The lower the earth resistance value, the greater the effect. Total uncertainty limits (range of true value) (A+B) = 99.5V to 100.5V What is AC ? Measurement Category •2 Measurement Principle of Low Resistance Testing• 2 Earth Resistance Testing• 2 What is Calibration ? Excessive overvoltage (impulse voltage) may also appear on power lines. AC (Alternating Current) is electric charge that Example AC Waveforms Current Clamp Meters 1 The resistance of copper wire changes according to the surrounding temperature. Earthing Systems (TN, TT and IT) Calibration is the work to verify the relationship between values that is indicated by periodically varies in terms of direction and The opening and closing of solenoid valves or loads at plants may cause high voltage spikes. a meter or measurement system, to the true values provided by a given standard, Ampère's right-hand grip rule • Magnetic field TN-S system TN-C system TT system Furthermore, since the wave peak value may be 10 times the power supply voltage or more magnitude. A typical AC waveform is a sine Resistance Generator / Transformer Generator / Transformer Generator / Transformer standard sample, or other defined equipment When a current flows, a magnetic field is generated concentrically. Rt = Rt0 ×{ 1 + αt0 × (t - t0) } L1 L1 L1 wave, and commercial power supply is made of in the case of inductive loads, etc., the IEC standard provides a correlation between the Current Grid and customer are The magnitude of the magnetic field is proportional to the magnitude L2 L2 L2 sinusoidal AC voltage signals. Sine Square nominal system voltage (power supply line voltage), overvoltage level, and measurement Rt L3 L3 L3 connected to the of the current. The direction of the magnetic field is the direction in Rt : Actually tested resistance [Ω] N PEN N Magnitude and values change as time passes (aging) category as an indication of transient overvoltage. which a screw is tightened if the direction of movement of the screw PE different earth and the direction of current are matched. This law is called "Ampère's Rt0 : Compensated resistance [Ω] Earth Consumer Earth independently. + Rt0 Earth Consumer Earth Consumer right-hand grip rule". High precision instruments generally exhibit Compensate t0 : Reference temperature [°C] Rated voltage to Recommended Impulse Withstand Voltage Magnitude Value little change over time 0 Sawtooth Triangular Measurement principle of current testing t : Current ambient temperature [°C] TN-C-S system IT system ground [V] CAT II CAT III CAT IV Current generated Generator / Transformer Generator / Transformer t0 t Temperature αt0 : Temperature coefficient at t0 Time When the magnetic field changes, a current is induced in the coil due to fluctuating L1 Connected to the L1 Grid is not connected to - 300 2500 4000 6000 L2 L2 through which it penetrates. The magnitude of the current is magnetic field L3 common earth through L3 the earth. 600 4000 6000 8000 determined by the magnetic fluctuation. By measuring the induced N By using a temperature-compensated resistance meter, PE grid. Safe against leakage. Low precision instruments generally exhibit I=0 I I=0 I I=0 current, the magnitude of the magnetic field is known as it flows in the Pulse Distorted 1000 6000 8000 12000 conductor, making it possible to measure the current at that time. you can automatically capture the temperature-converted resistance value. Earth Consumer Consumer Earth large change over time Describing AC Signal Measurement Category •3 Measurement Principle of Insulation Resistance Testing• 1 Earth Resistance Testing• 3 Why is Calibration Necessary ? Instantaneous : Level that occurs instantaneously 2 Calibration requirements stipulated by Example of Overvoltage at Example of Damage due Current Clamp Meters Objective Measurement principle of Current meter AC power Maximum and Minimum : The highest and lowest values Open/Close of Solenoid Valve to Misuse of Tester an earth resistance tester I ISO9001:2008: •Measured Insulation resistance is measured in order to ensure the safety of electrical equipment / parts and electrical facilities etc. I A Peak-to-Peak : Difference between the maximum and minimum Structure of a current clamp meter Magnetic flux from conductor +1000V measured current 1.
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