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How to Set My Sperry SP-5A Amp Meter for Wattage on a Pontoon

It is common practice to measure the electrical characteristics of a motor. Key quantities include the voltage used by a motor, the current flowing through a motor and the electrical power (wattage) that the motor uses. Under most circumstances, the electrical power would be measured using a multimeter with a power function, but it can also be measured using other meters. A Sperry SP-5A meter is a multimeter which has the capability of measuring voltage, current and resistance. The use of a simple equation allows the power to be calculated from the measured voltage and current.

Instructions

- 1
  Connect the measurement probes to the meter. Two leads are provided with the meter. Plug the red lead into the positive terminal and the black lead into the negative terminal.
- 2
  Switch on the Sperry SP-5A meter by rotating the dial on the front. Select the 250V voltage function. Place the measurement probes across the two input terminals of the motor. The needle on the meter display should rotate to the right. Read the value of the voltage off the middle scale which ranges from 0V to 250V.
- 3
  Rotate the dial on the front of the meter to the 250 milliamp (mA) current measurement setting. Place the measurement probes across the two inputs of the motor. The needle on the meter display will rotate to the right. Read the measured value of current off the middle scale that ranges from 0 mA to 250 mA.
- 4
  Multiply the measured value of current (in amps) by the measured value of voltage (in volts) in order to get the power in watts. For example if 150 volts is measured for the voltage and 100 mAmps (0.1A) is the measured for the current, then the power is: P=VI= 150 x 0.1 = 15 watts

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