SATEC EM920 Operation Manual - Manual (Page 220)

Appendix F EN50160 Evaluation and Recording
220 EM920 Power Quality and Revenue Meter
The overvoltage threshold can be changed in the meter via
the EN50160 PQ Recorder setup.
The basic voltage measurement is one-cycle RMS voltage
updated each half-cycle.
Statistical Survey
The EM920 provides the statistical evaluation of temporary
overvoltages using the classification recommended by
Eurelectric’s Measurement guide for voltage characteristics.
Temporary overvoltages are classified by voltage magnitude
and duration as shown in Appendix E.
Indicative Values
Temporary overvoltages on the low voltage side will generally
not exceed 1.5 kV RMS.
Transient Overvoltages
Transient overvoltages correspond to disturbances of very
short duration, lasting typically less than one half-cycle, i.e. a
few microseconds to several milliseconds.
Method of Evaluation
Transient overvoltages are detected as impulsive or low
frequency oscillatory transients with a rise time less than 0.5
ms and duration from 20 us with the Fast Transient
coprocessor option or from 75 us without it and to ½ cycle.
The impulse magnitude is evaluated either by the peak
voltage value, or by the impulse amplitude, and is referenced
to the nominal voltage amplitude (1.414 Un). The meter can
detect transient overvoltages with a magnitude of up to 2 kV
with the fast transient coprocessor option or up to 700V
without it.
Statistical Survey
The EM920 provides the statistical evaluation of transient
overvoltages using the classification recommended by
Eurelectric’s Measurement guide for voltage characteristics.
Transient overvoltages are classified by voltage magnitude as
shown in Appendix E.
Indicative Values
Transient overvoltages in LV systems will generally not
exceed 6 kV peak, but higher values occur occasionally.
Voltage Unbalance
This characteristic defines the magnitude and/or phase
asymmetries of three-phase steady state supply voltage.
Method of Evaluation
The basic measurement is the RMS value of the steady state
voltage unbalance over a period of 10 minutes under normal
operating conditions. It is defined using the theory of
symmetrical components by the negative sequence