Multi-Tech Systems 7500 - Manual (Page 315)

ION 7500 / ION 7600 User’s Guide Supply Voltage Unbalance
Power Quality: ION Meters and EN50160 Technical Note Page 315
Supply Voltage Unbalance
Each basic measurement is the true RMS value over a fixed 10-minute period (see
the UNIPEDE Measurement Guide for Voltage Characteristic for more details).
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 the voltage unbalance exceeds 2% (3% in
some areas) and the supply voltage is within ±15% of nominal.
Voltage unbalance complies with the standard if N
1
/N <= 5% during the
observation period (1 week by default).
EN 50160 data (current observation period): The meter generates the N and N
1
counts as described above. These counters are reset at the beginning of the next
observation period.
EN 50160 data (previous observation period): The meter stores the N and N
1
counter values at the end of each observation period before these counters are
reset. These 2 registers are also stored in a data recorder for each observation
period.
Events: A message is created in the Event log every time the N
1
counter increases.
Unbalance Default Measurements
* This data is recorded once every week by Data Recorder 28.
Each measurement
is the RMS
unbalance voltage:
Register Label Module Type Description
Vubal N*
Signal Limit Evaluation
Number of valid intervals (voltage on all phases within +/- 15% of nominal)
Vunbal N invld* Number of invalid intervals
Vunbal N1* Number of valid intervals in which the voltage unbalance exceeds 2%
PO Vunbal N
Store
Vunbal N of the previous Observation Period
PO Vunbal N1 Vunbal N1 of the previous Observation Period
Vunbal mean Sliding Window Demand Average voltage unbalance over 10 minutes (used for display purposes)
Vunbl mean mn Minimum Minimum average voltage unbalance over 1 week (used for display purposes)
Vunbl mean mx Maximum Maximum average voltage unbalance over 1 week (used for display purposes)
Vunbal N1/N
Arithmetic
N1/N ratio
PO Vunbal N1/N N1/N ratio of the previous Observation Period