Voltage measurements
Measuring of voltage
Schem of a voltage measurment
  1. Take the measurement in the emerging voltage wires from the main switch to the motor-pump.
  2. Place the red cable of the tester on the tip of the switch output in the “a” line.
  3. Place the black cable of the tester on the tip of neutral “n.”
  4. Register the reading for the “a” phase voltage (Van).
  5. Repeat the action, putting the red cable of the tester in output tips “b” and “c” of the switch (with the black connected to neutral ground) and take respective readings of tension (Vbn) in phase “b” and tension (Vcn) in phase “c.”
  6. When measuring the voltage between phases, repeat the procedure above by placing the red wire of the voltmeter on the output switch in point “a” and the black cable into the “b” end; then between “a” and “c”; and finally between “b” and “c.”
Current measurement
Current measurment
Scheme of a current measurement

- When using an ammeter, perform single-phase electrical current readings one by one by placing the ammeter in each of the three cables coming out of the main switch or starter and fed to the motor. Readings in each cable shall be flow phases Ia, Ib, and Ic, and the electrical three-phase total current is calculated with these three values. Take three readings in each cable to corroborate the data.


- If you use an electric network analyzer, take electrical current readings individually, but place the three amps simultaneously in each of the cables coming out of the switch and leading to the engine. The electrical currents of each of the cable readings are obtained directly by the online scanner.

Active power measurement

A wattmeter, which is put in the output switch cable, is used to measure the actual power going to the
engine. The procedure for measuring the value of the real or active power is as follows:

  1. Put wattmeter on phase “a” wire on voltage terminals.

  2. Put another voltage terminal in the neutral wire on “n.”

  3. Insert the ammeter hook in the “a” phase wire.

The real or active power registers directly in the wattmeter. Repeat the above process to obtain the
real power in phases “b” and “c.”

Power of electric motor calculation
After measuring parameters you can do analyses of a pumping system.