Commit 347d9df1 by avassil

### Review: calculate power rating of the component, small arangements to the PCB,

parent cae01622
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 ... ... @@ -4,7 +4,7 @@ A set of AC and DC, voltage and current , sensor components provisioned for inte In this repository all the design issues are addressed and reusable schematic and pcb design components are developed. The datalogger is provisioned to be used at small wind turbine systems of nominal power 600W, 1kW and 1.8kW and with a battery storage of 24V and 48V. The sensor modules are sized based on these specifications and the design restrictions.The sized based on these specifications and the design restrictions.The # Electric Measurement isolation ... ... @@ -20,13 +20,39 @@ Digital side isolation is mainly used for medium resolution and medium sampling The most common sensor technologies today are the * current transformer (CT) and the * low resistance current shunt. * Hall Effect transducers * Rogowski coil # Circuit Design ## AC Current For the measurement of the 3ph AC currents the use of Current Transformers (CT) is decided. ### CT Burden Calculations Burden resistance affects the accuracy of the CT, as the burden resistance increases, the magnetic impedance draws more current, which results in measurement error and nonlinearity for the entire range. Let say that: math I_{p} = Primary current I_{s} = Secondary current N = Turn ratio Z_{m} = Core impendance calculated at the Secondary Z_{s} = Secondary source impendance R_{B} = Burden resistanse Error calculation: V_{measur} = I_{s} \cdot (\frac {(Z_{m} \cdot (Z_{s} + R_{B}))} {Z_{m} + (Z_{s} + R_{B})} ) V_{real} = I_{m} \cdot Z_{m} I_{B} = I_{s} - I{m}  * CST-1030 I_{nominal} = 30A N = 1:1000 Nonlinear zone = 45-65Hz math R_{B} = \frac {200mV \cdot N} {I_{P}} = 6.67 ohm  ## AC Voltage In such applications, usually a resistor divider (R1 and R2) is used to match the relatively small input voltage range of the ADC. A differential isolation amplifier is used at the analog side. ... ...
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