ABB Distribution Protection Unit 1500R
3-1
Metering
9/99
website:www.abb.com/papd
Metering
The DPU1500R contains a complete voltage and current metering package. It also calculates sequence components,
real and reactive power flow, power factor, demand, and minimum/maximum values. The proper setting of the Voltage
Transformer (VT) and Current Transformer (CT) configurations and ratios are extremely important for proper metering
operation. The VT and CT configuration (wye or delta) and ratio settings are contained in the “Configuration Settings”
menu (see Section 2). Load magnitudes for kilovolts and current are displayed by default on the LCD display (if
applicable). They can also be displayed in the WinECP metering screen. The voltage values displayed are phase to
neutral for wye connected VT’s and phase to phase for delta connected VT’s. Voltage Van or Vab for delta VT’s is
always shown at 0 degrees and is used as a reference for all other voltage and current phase angles. The calculated
sequence voltage components V
1
and V
2
are derived from the line voltages regardless of VT configuration. If a
balanced condition is assumed then: In a delta system, the angle of the positive sequence voltage (V
1
) leads Vab by
330 degrees. In a wye system the angle of the positive sequence voltage (V
1
) equals Van. The metering screen can
be used to verify proper and healthy connections to the voltage and current input sensors of the DPU1500R.
The following is a description of all the DPU1500R metering features.
Load Metering
The following load values are contained in the DPU1500R and are accessible via the MMI or WinECP program:
All phase angles are referenced to V
an
which is set to be zero degrees.
•
Phase Currents: Magnitude and Phase Angle (wye or delta connections)
•
Ground Current: Magnitude and Phase Angle (wye or delta connections)
•
Kilovolts: Magnitude and Phase Angle (wye or delta connections)
•
Kilowatts (or Megawatts): Single Phase and Three Phase for wye VT’s and Three Phase for Delta VT’s
•
KiloVArs (or MegaVArs): Single Phase and Three Phase for wye VT’s and Three Phase for Delta VT’s
•
Kilowatt-hours (or Megawatt-hours): Single Phase and Three Phase for wye VT’s and Three Phase for Delta VT’s
•
KiloVAr-hours (or MegaVAr-hours): Single Phase and Three Phase for wye VT’s and Three Phase for Delta VT’s
•
Voltage Sequence Components: Magnitude and Phase of Positive Sequence (V
1
) and Negative sequence (V
2
)
voltage
•
Current Sequence Components: Magnitude and Phase Angle of Positive Sequence (I
1
), Negative Sequence (I
2
),
and Zero Sequence (I
0
) current
•
Power Factor
•
Frequency
Energy Meter Rollover
The Watt-hour and VAr-hour or Energy meters can be set to display Kilowatt-hours or Megawatt-hours. This setting
is made in the “Configuration” menu (see Man Machine Interface or Windows External Communication Program).
Depending on the magnitude of the power flow seen by the DPU1500R and the time period between meter readings,
it may be necessary to switch the meter mode to megawatt-hours to avoid energy meter rollover. Meter rollover is the
point at which the DPU1500R watt-hour meter has reached its maximum count and returns to zero to begin incrementing
again. The roll over point for the energy meters is 6,000,000 kilowatt-hours (kiloVAr-hours) in the Kwhr mode and
2,000,000,000 megawatt-hours (megaVAr-hours) in the Mwhr mode.
The energy meters are capable of reading negative power. If the magnitudes are positive, the meters will increment,
if negative they will decrement. Figure 3-1 outlines the metering conventions used in the DPU1500R.
