Multi-Tech Systems 7500 - Manual (Page 316)

Harmonic Voltage ION 7500 / ION 7600 User’s Guide
Page 316 Power Quality: ION Meters and EN50160 Technical Note
Harmonic Voltage
All harmonic measurements are performed as defined by IEC 61000-4-7.
Observation period of one week with fixed steps of 10 minutes.
N = number of 10-minute intervals in which the supply voltage is within ±15% of
nominal.
N
1
= number of intervals in which one or more of the individual harmonic levels
defined in the table below are exceeded and the supply voltage is within ±15% of
nominal. Levels for individual harmonics (for each phase) up to the 25th are
defined in the table below.
N
2
= number of intervals in which the THD value for one or more of the voltage
phases exceeds 8% and the supply voltage is within ±15% of nominal. The THD
calculation will include all harmonics up to the 40thd).
Harmonic voltage complies with the standard if N
1
/N <= 5% and N
2
/N <= 5%
during the observation period (1 week by default).
EN 50160 data (current observation period): The meter generates the N, N
1
and
N
2
counts described above for each phase. These counters are reset at the
beginning of the next observation period.
EN 50160 data (previous observation period): The meter stores the N, N
1
and N
2
counter values at the end of each observation period before these counters are
reset. These 9 registers are also stored in a data recorder for each observation
period.
Events: The meter creates a message in the Event log every time the N
1
and N
2
counters increase.
Parameter data: The meter can be enabled to record the 10-minute mean,
minimum and maximum values of THD, TO(odd)HD and TE(even)HD
for each
voltage phase into a data recorder every 10 minutes.
Odd Harmonics Even Harmonics
Not Multiples of 3 Multiples of 3 Order Threshold
Order Threshold Order Threshold Order Threshold 2 2%
5 6% 17 2% 3 5% 4 1%
7 5% 19 1.5% 9 1.5% 6…24 0.5%
11 3.5% 23 1.5% 15 0.5%
13 3% 25 1.5% 21 0.5%