• any output intended for testing the accuracy of the meter does not produce pulses or signals corresponding to an energy of more than the critical change value,

and in reasonable time after the disturbance the meter shall:

• recover to operate within the MPE limits, and

• have all measurement functions safeguarded, and

• allow recovery of all measurement data present prior to the disturbance, and

• not indicate a change in the registered energy of more than the critical change value.

The critical change value in kWh is $m\times U_n\times I_{\max }\times {10}^{\mathrm{–6}}$

(m being the number of measuring elements of the meter, U_n in Volts and I_max in Amps).

For overcurrent the critical change value is 1,5 %.