GE Industrial Solutions Entellisys 5.0 User Manual - Manual (Page 41)

Harmonics metering 41
4
For block demand, Entellisys calculates the average demand over the duration of the demand
interval. For rolling demand, Entellisys calculates the average demand over the previous N
subintervals, where N is the number of subintervals per demand interval. This is done at the end
of each demand subinterval. Demand intervals are synchronized to the hour boundary. For
example, if the demand interval or subinterval length is 15 minutes, the demand intervals end
on the hour and at 15, 30, and 45 minutes past the hour.
The programmed interval length (block demand) or subinterval length and the number of
subintervals per demand interval apply to all circuit breakers at which demand metering is
enabled.
Demand log entries are added at the end of each demand interval or subinterval.
4.4 Harmonics metering
Harmonics metering is an optional feature in Entellisys. Harmonics metering can be enabled for
each circuit breaker, up to the maximum number of purchased harmonics metering options.
When the harmonics metering option is enabled, Entellisys provides the following quantities:
•
All quantities available with the demand metering option
•
K factor for each current phase
•
Voltage Total Harmonic Distortion (VTHD) for each phase
•
Current Total Harmonic Distortion (ITHD) for each phase
•
Frequency spectrum (magnitude only) for voltage and phase
Entellisys samples at 64 samples per cycle, so it will display the up to the 31 st harmonic.
x x x
Table 4-1 Demand interval and subinterval combinations supported in Entellisys
Subintervals per
interval Subinterval length, minutes
1 2 3 4 5 6 10 15 20 30 60