Calibration Command

The configuration command (“CAL”) is used to automatically calibrate the board. It requires accurate and stable voltage and current sources and loads, which can be provided by a meter test bench like the WECO (or equivalent equipment). Refer to Calibrate the Demo Board Using the Demo Meter Application for additional information.

This command must be sent after a configuration command, to ensure that the proper configuration was applied.

There are four variants of the calibration command:

  • “CAL_A”, to calibrate the phase A individually
  • “CAL_B”, to calibrate the phase B individually
  • “CAL_C”, to calibrate the phase C individually
  • “CAL_T”, to calibrate a three phases system simultaneously

The configuration command has the following parameters:

  • “CAL_A”, “CAL_B” and “CAL_C” commands:
    • Ua (for “CAL_A), Ub (for “CAL_B), Uc (for “CAL_C): Rms voltage applied to the voltage input. Units: Volts
    • Ia (for “CAL_A), Ib (for “CAL_B), Ic (for “CAL_C): Rms current applied to the current input. Units: Amps
    • Aa (for “CAL_A), Ab (for “CAL_B), Ac (for “CAL_C): Angle between the voltage and current vectors. Units: Degrees. The value is positive if the current is lagging the voltage
  • “CAL_T” command:
    • Ua: Rms voltage applied to the voltage input (phase A). Units: Volts
    • Ub: Rms voltage applied to the voltage input (phase B). Units: Volts
    • Uc: Rms voltage applied to the voltage input (phase C). Units: Volts
    • Ia: Rms current applied to the current input (phase A). Units: Amps
    • Ib: Rms current applied to the current input (phase B). Units: Amps
    • Ic: Rms current applied to the current input (phase C). Units: Amps
    • Aa: Angle between the voltage and current vectors (phase A). Units: Degrees. The value is positive if the current is lagging the voltage.
    • Ab: Angle between the voltage and current vectors (phase B). Units: Degrees. The value is positive if the current is lagging the voltage.
    • Ac: Angle between the voltage and current vectors (phase C). Units: Degrees. The value is positive if the current is lagging the voltage.

The maximum resolution available is 0.001V (voltages), 0.0001A (currents), 0.001º (angles) and 0.01 Hz (frequency).

Examples:

  • Calibrate phase A, applying 220.00V, 5.000A, angle=60.00º: “CAL_A (Ua=220.00,Ia=5.000,Aa=60.00)”
  • Calibrate phase B, applying 230.00V, 10.000A, angle=60.00º: “CAL_B (Ub=230.00,Ib=5.000,Aa=60.00)”
  • Calibrate phase C, applying 120.00V, 1.000A, angle=60.00º: “CAL_C (Uc=120.00,Ic=1.000,Aa=60.00)”
  • Calibrate a three phases system, applying to all phases 220.00V, 5.000A and a phase shift of 60.00º: “CAL_T (Ua=220.00,Ia=5.000,Aa=60.00,Ub=220.00,Ib=5.000,Ab=60.00,Uc=220.00, Ic=5.000, Ac=60.00)”