2.5.5.11 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 2.3 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:

• The 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
• The 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)”