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, themeasured value below a settable limit is forced to zero which reduces the impact of noise inthe inputs.Dead-band supervision can be used to report measured signal value to station level whenchange in measured value is above set threshold limit or time integral of all changes since thelast time value updating exceeds the threshold limit. Measure value can also be based onperiodic reporting.The measurement function, , 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 measuring functions CMMXU, VMMXU and VNMMXU 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)The function calculates three-phase power quantities by using fundamental frequency phasors(DFT values) of the measured current respectively voltage signals. The measured powerquantities are available either, as instantaneously calculated quantities or, averaged valuesover a period of time (low pass filtered) depending on the selected settings.It is possible to calibrate the measuring function above to get better then class 0.5presentation. This is accomplished by angle and amplitude compensation at 5, 30 and 100% ofrated current and at 100% of rated voltage.The power system quantities provided, depends on the actual hardware, (TRM)and the logic configuration made in PCM600.The measuring functions CMSQI and VMSQI provide sequence component quantities:• I: sequence currents (positive, zero, negative sequence, amplitude and angle)• U: sequence voltages (positive, zero and negative sequence, amplitude and angle).13.1.3 Zero clamping GUID-8DABC3F5-6615-493C-B839-A5C557A2FAE8 v3The measuring functions, CVMMXN, CMMXU, VMMXU and VNMMXU have no interconnectionsregarding any setting or parameter.Zero clampings are also entirely handled by theZeroDb for each and every signal separately foreach of the functions. For example, the zero clamping ofU12 is handled byUL12ZeroDb inVMMXU, zero clamping of I1 is handled byIL1ZeroDb in CMMXU ETC.Example how CVMMXN is operating:Section 13 1MRK 504 158-UEN AMonitoring200Application manual
