ABB Distribution Protection Unit 1500R
3-2
Metering
9/99
website:www.abb.com/papd
The update rate of the energy meters is based on the “Demand Constant”
setting (see Demand Meter Section) as set in the “Configurations”
settings. The meters will update every 1/15 of the Demand Constant.
For example: if the Demand Constant is set to 15 minutes the energy
meters will update every 1 minute (15min x 1/15 = 1 min).
The watt-hour and VAr-hour meters can be reset to 0 by the local Man
Machine Interface (MMI) only. “Reset Energy Meters” is found in the
“Meter” Menu.
Demand Metering
Demand metering is typically used for analysis of equipment loading and system planning. The demand values in the
DPU1500R are accessible via the MMI or WinECP program. The following are the measurements taken by the demand
meter:
Phase Currents: Magnitude and Phase Angle (wye or delta connections)
Ground Current: Magnitude and Phase Angle (wye or delta connections)
Kilowatts: Single Phase and Three Phase for wye VT’s and Three Phase for Delta VT’s
KiloVArs: Single Phase and Three Phase for wye VT’s and Three Phase for Delta VT’s
The demand meter takes a snapshot of the load every 1/15 x Demand Constant minutes. The demand currents are
averaged using a log
10
function over the period of the Demand Constant Interval to replicate thermal demand ammeters.
The demand kilowatts and kiloVArs are averaged values that are calculated by sampling the kilowatt-hours and
kiloVAr-hours every “Demand Constant” interval. The Demand Constant interval is a setting made in the “Configuration”
settings and is the time period between demand meter updates. Current utility or industrial practice usually dictates
the setting of the demand constant interval.
Minimum / Maximum Metering
During each demand interval described above, the DPU1500R also captures and stores minimum and maximum values
for the measurements listed below. It functions as a standard minimum / maximum meter given that when a new
maximum or minimum value is determined, the old value is replaced. A time stamp is placed with the latest minimum
and maximum values. The minimum / maximum meter measures:
Phase Currents: Magnitude and Phase Angle (wye or delta connections)
Ground Current: Magnitude and Phase Angle (wye or delta connections)
Kilowatts: Single Phase and Three Phase for wye VT’s and Three Phase for Delta VT’s
KiloVArs: Single Phase and Three Phase for wye VT’s and Three Phase for Delta VT’s
90
0
270
0
0
0
180
0
-KVAR
Van
Ia
+KVAR
-Kw
+Kw
Figure 3-1. Metering Conventions
Used in the DPU1500R
