Loss due to the instrument connection method

Loss due to the instrument connection method

Question

Do measured values vary with the power meter connection?

Answer

When connecting the instrument, the voltage input terminals can be connected to the load, or the current terminals can be connected to the load. Which connection should be used varies with the magnitude of the voltage and current being measured.

Connecting the voltage terminals to the load
Power measurements will include loss from the voltage input terminals’ input resistance. Loss due to the instrument can be minimized when the measured voltage is low and the measured current is small.

Connecting the current terminals to the load
Power measurements will include loss from the current input terminals’ input resistance. Loss due to the instrument can be minimized when the measured voltage is high and the measured current is small.

When using clamp-on sensor input, the sensor’s loss can be ignored for the most part.