SP-214-SS 放大 4-20 毫安總輻射表概括：

User's Manual

Apogee model SP-214 pyranometers provide a 4-20 mA output that is proportional to incident total shortwave radiation. A quick and easy check of sensor functionality can be determined using a DC power supply and an ammeter. Power the sensor with a DC voltage by connecting the positive voltage signal to the red wire from the sensor and the negative (or common) to the black wire from the sensor. Use the ammeter to measure across the white wire (signal output) and black wire (signal ground). Direct the sensor head toward a light source and verify the sensor provides a signal. Increase and decrease the distance from the sensor head to the light source to verify that the signal changes proportionally (decreasing signal with increasing distance and increasing signal with decreasing distance). Blocking all radiation from the sensor should force the sensor signal to 4 mA

The 4-20 mA circuit design allows the output to drive a resistive load (RL) to within 2 volts of the supply voltage to the sensor (VS), at 20 mA (0.02 A). The equation to calculate resistive load is RL = [VS – 2 V] / 0.02 A. For example, a sensor with a supply voltage of 12 V DC can drive a maximum load of 500 Ω (RL = [12 V – 2 V] / 0.02 A = 500 Ω). The output voltage from the sensor is calculated by adding the wire resistance to the input resistance of the data collection system, and then multiplying by 0.02 A.

SP-214-SS drawing：

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SP-214-SS rules: