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Energy & Power Meters History & Measurement Principle. Ben Kemink. Current Transformer Input. 1960’s. 70’s. 80’s. 90’s. (50 - 60 Hz). Electro-dynamic Wattmeter. Traditional Stable Loads. APR2. Torque Balanced Type. 2885 (50 - 400 Hz). 2533 (DC, 10Hz - 20kHz).
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Energy & Power Meters History &Measurement Principle Ben Kemink
Current Transformer Input 1960’s 70’s 80’s 90’s (50 - 60 Hz) Electro-dynamic Wattmeter Traditional Stable Loads APR2 Torque Balanced Type 2885 (50 - 400 Hz) 2533 (DC, 10Hz - 20kHz) Time Division Multiplier Type Digital Display Power Meters Current Shunt Input Traditional Stable Loads 2532(DC,20Hz-400kHz)) WT1600 (DC,0.5Hz-1MHz)) Digital Sampling Power Meters New Generation Un-Stable Loads PZ4000 DC – 2MHz WT230 (DC,0.5Hz-100kHz)) Single Shot Power Meter WT3000 (DC, 0.1Hz-1MHz) History and Types of Energy & Power Meters
Thermocouple WATT-meter The thermocouple generates a DC-voltage proportionally to the temperature difference of the junction and the reference point. A moving coil instrument is used to indicate the result. This instrument can be used to measure both DC and AC. Frequency bandwidth Current: up to approx. 10 MHz Voltage: up to approx. 100 kHz The heating-wire is very thin and easily burned out by an over-current.
Electro-Dynamic WATT-meter If fixed coils are representing the load-current and the moving coil the voltage-representative current, we are directly measuring electric power. This instrument can measure DC and AC. Frequency bandwidth Current: up to approx. 1000 Hz Voltage: up to approx. 150 Hz
u(t) Voltage input circuit Analogue multiplier Low pass filter X i(t) Current input circuit p(t)=u(t).i(t) RMS circuit To A/D converter MEAN circuit RMS circuit Average power Analogue Measurement, Digital Readout
Analogue calculation, Digital Readout Yokogawa 2533E
Sampled Instantaneous voltage value U(n) Voltage input circuit u(t) A/D Sampled Instantaneous current I(n) To next stage DSP Current input circuit i(t) A/D Digital Signal Processing Today: WT-Family en PZ
Example of true digital type Yokogawa 2531A
1950s 1980s Present time Near future Stability / Repeatability Accuracy / Bandwidth Real time / Analysis Efficiency / Control Requirement Background Boom of Inverter Harmonics / Flicker Ecology / Energy Boom of house appliances Object / Target Commercial frequency Static power Static power / Analysis Transient power Sensing Coil CT, DC/CT Non inductive shunt High freq . probe/sensor Method Moving coil Analog circuit or IC Digital circuit or IC Digital IC A-D V Fixed V V A-D DSP coils LPF A-D A Moving A A A-D coil A-D DSP A-D Fixed CPU DSP coil A-D CPU Pointer CPU CRT Moving of meter coil Fixed MEMORY MEMORY coil Principle or Electrodynamometer Feedback time division DSP DSP multiplier system Acquisition Digital multiplier Sampling A/D C Feedback pulse width method Sampling A/D C modulation Counting A /D C Real time FFT analysis Theme Accuracy Isolation / Software Probing/ Calibration Response Energy & Power Measurement Trend