ABB REG650 Technical Manual page 357

1MRK 502 034-UEN -
Technical Manual
instrument transformers (CTs and VTs). During normal service by periodic
comparison of the measured value from the IED with other independent meters the
proper operation of the IED analog measurement chain can be verified. Finally, it
can be used to verify proper direction orientation for distance or directional
overcurrent protection function.
The available measured values of an IED are depending on the
actual hardware (TRM) and the logic configuration made in PCM600.
All measured values can be supervised with four settable limits that is, low-low
limit, low limit, high limit and high-high limit. A zero clamping reduction is also
supported, that is, the measured value below a settable limit is forced to zero which
reduces the impact of noise in the inputs. There are no interconnections regarding
any settings or parameters, neither between functions nor between signals within
each function.
Zero clampings are handled by ZeroDb for each signal separately for each of the
functions. For example, the zero clamping of U12 is handled by ULZeroDb in
VMMXU, zero clamping of I1 is handled by ILZeroDb in CMMXU.
Dead-band supervision can be used to report measured signal value to station level
when change in measured value is above set threshold limit or time integral of all
changes since the last time value updating exceeds the threshold limit. Measure
value can also be based on periodic reporting.
The measurement function, CVMMXN, provides the following power system
quantities:
• P, Q and S: three phase active, reactive and apparent power
• PF: power factor
• U: phase-to-phase voltage amplitude
• I: phase current amplitude
• F: power system frequency
The output values are displayed in the local HMI under Main menu/Tests/
Function status/Monitoring/CVMMXN/Outputs
The measuring functions CMMXU, VNMMXU and VMMXU provide physical
quantities:
• I: phase currents (amplitude and angle) (CMMXU)
• U: voltages (phase-to-earth and phase-to-phase voltage, amplitude and angle)
(VMMXU, VNMMXU)
It is possible to calibrate the measuring function above to get better then class 0.5
presentation. This is accomplished by angle and amplitude compensation at 5, 30
and 100% of rated current and at 100% of rated voltage.
Section 13
Monitoring
351