![]() The output voltage is proportional to the electric current flowing in the conductor being measured.Ģ.This total secondary electric current flows to the shunt resistor, producing a voltage across the terminals.Then, a feedback current is added through an amplifier circuit so as to cancel out the magnetic flux (Φ-Φ’) in the low-frequency regions. The detecting coil detects this remaining magnetic flux (Φ-Φ’).However, in the low-frequency regions, the magnetic flux (Φ-Φ’) cannot be cancelled and thus remains in the magnetic circuit.In the zero-flux method, in order to cancel out the magnetic flux (Φ) produced inside the magnetic core by the AC current flowing in the conductor being measured, a secondary electric current flows to the feedback winding, inducing a secondary magnetic flux (Φ’).The current sensor of zero flux type (winding detection type) achieves high performance (high accuracy and wide bandwidth) by adding a negative feedback circuit to the basic winding method. The output voltage is proportional to the measured current. This produces a voltage across its terminals. This electric current is a sum of the current from the CT effect (current generated by the coil) and the amplifier (feedback current from Hall element detection). The secondary electric current then flows through the coil and into the shunt resistor ( r). Then, a secondary feedback current is added through an amplifier circuit so as to cancel out the remaining magnetic flux (Φ-Φ’). 4.The Hall element detects this remaining magnetic flux (Φ-Φ’).(The remaining magnetic flux in the magnetic core comes out to Φ-Φ’) 3.However, in the low-frequency regions resulting from DC currents, the magnetic flux cannot be cancelled and thus remains in the magnetic circuit.(The magnetic flux of the feedback winding is marked as Φ’) 2.A secondary electric current flows to the secondary side of the feedback winding, in order to cancel out the magnetic flux produced inside the magnetic core.1.A magnetic flux (Φ) is produced inside the magnetic core by the electric current flowing in the conductor being measured.Note:The explanation below is based on the detection when a Hall element is used.Bare board, Package, Populated Board Testing.Ground Resistance, Phase Rotation, Voltage Detection. ![]() Testers, Handheld Digital Multimeters (DMMs).Magnetic Field, Temperature, Sound Level, Lux, Rotation.Solar Panel/Photovoltaic (PV) System Maintenance.RGB Laser/LED Optical Meters, LAN Cable Testers.Optical, PV maintenance, Telecommunication.Current Probes/Sensors, Voltage Probes, CAN Sensors.Electrical Safety Testers, Hipot/Insulation/Leakage Testers.Super Megohmmeters, Electrometers, Picoammeters.LCR Meters, Impedance Analyzers, Capacitance Meters. ![]() Compact Data Loggers, Temperature Data Loggers.Data Acquisition, Oscilloscopes, Memory Recorders.The thermal conductivity for glass is typically about k = 1.0 W/m-K and the thickness is about L = 3 mm. Neglect radiation and solve the conduction equation for the temperature difference across the glass for the average heat flux. What reasons would cause the magnitude of heat flux measured values to not be equal?Ĥ. What does it say about the relation between your measured heat flux values?ģ. Apply an energy balance around the window. Why do the heat flux values have opposite sign between the inside and outside of the window?Ģ. Record the steady-state values below and sketch the temperature distribution on the figure. ![]() Use the second thermocouple to record the air temperature at the same time. Then repeat for the outside of the window. Measure the heat flux and temperature at steady-state. Mount the heat flux sensor on the inside of the window with the thermocouple on the side next to the glass. Consequently, contrary to popular opinion it is normally much easier to accurately measure heat flux on a surface than temperature. Conversely, the heat flux is typically measured over a much larger area and at steady-state conditions, what goes in must come out. Thermal contact resistance is relatively large, especially for the usual bead thermocouples. Note: It is very difficult to accurately measure the surface temperature of materials when heat transfer is occurring to or from the surface. Where k is the thermal conductivity of the glass and L is the thickness. At steady-state conditions the conduction heat flux is The thermal resistance of the window should be measurable from the heat flux q" and temperature difference across the glass ΔT. ![]() This is still the case in the older engineering buildings on our campus. Many older windows and storm doors use a single pane of glass, typically 1/8 inch thick. Windows are a major source of heat loss in buildings. ![]()
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