1.6 Creep (Start-up/No load)

The metrology firmware supports start-up/no load by creep features; three creep thresholds are defined:

Any phase energy with RMS value less than CREEP_THRESHOLD_I will not be accumulated.

The total active energy is accumulated only when the active energy in a full cycle is greater than CREEP_THRESHOLD_P.

The total reactive energy is accumulated only when the reactive energy in a full cycle is greater than CREEP_THRESHOLD_Q.

CREEP_THRESHOLD_x ( x = P or Q) is the creep energy (Watt-hour or Var-hour) in a full cycle (20 ms for 50 Hz, 16.6667 ms for 60 Hz).

The metrology uses Q30 to represent both integer and fractional numbers for CREEP_THRESHOLD_x.

CREEP_THRESHOLD_I is the creep current; it is recommended to be calculated according to the following formula:

Where I_CREEP-RMS is the required creep current, the unit is mA. K_lx is the current conversion factor of float point.

Example:

If the creep threshold is set to 10 mA, K_lx = 617.28396, then:

CREEP_THRESHOLD_I = ROUND(10 / 617.28396 * 2²⁰) = 16987 = 0x0000425B