The functions can be enabled or disabled with the Operation setting. The corresponding parameter values are "On" and "Off".
Some of the measurement functions operate on two alternative measurement modes: "DFT" and "RMS". The measurement mode is selected with the Measurement mode setting. Depending on the measuring function if the measurement mode cannot be selected, the measuring mode is "DFT".
Value reporting
- Zero-point clamping
- Deadband supervision
- Limit value supervision
Zero-point clamping
A measured value under the zero-point clamping limit is forced to zero. This allows the noise in the input signal to be ignored. The active clamping function forces both the actual measurement value and the angle value of the measured signal to zero. In the three-phase or sequence measuring functions, each phase or sequence component has a separate zero-point clamping function. The zero-value detection operates so that once the measured value exceeds or falls below the value of the zero-clamping limit, new values are reported.
| Function | Zero-clamping limit |
|---|---|
| Three-phase current measurement (CMMXU) | 1% of nominal (In) |
| Three-phase voltage measurement (VMMXU) | 1% of nominal (Un) |
| Residual current measurement (RESCMMXU) | 1% of nominal (In) |
| Residual voltage measurement (RESVMMXU) | 1% of nominal (Un) |
| Sequence current measurement (CSMSQI) | 1% of the nominal (In) |
| Phase sequence voltage measurement (VSMSQI) | 1% of the nominal (Un) |
| Three-phase power and energy measurement (PEMMXU) | 1.5% of the nominal (Sn) |
Limit value supervision
- 0: "normal"
- 1: "high"
- 2: "low"
- 3: "high-high"
- 4: "low-low"
The range information can also be decoded into boolean output signals on some of the measuring functions and the number of phases required to exceed or undershoot the limit before activating the outputs and can be set with the Num of phases setting in the three-phase measurement functions CMMXU and VMMXU. The limit supervision boolean alarm and warning outputs can be blocked.
|
Function |
Settings for limit value supervision |
|
|---|---|---|
| Three-phase current measurement (CMMXU) | High limit | A high limit |
| Low limit | A low limit | |
| High-high limit | A high high limit | |
| Low-low limit | A low low limit | |
| Three-phase voltage measurement (VMMXU) | High limit | V high limit |
| Low limit | V low limit | |
| High-high limit | V high high limit | |
| Low-low limit | V low low limit | |
| Residual current measurement (RESCMMXU) | High limit | A high limit res |
| Low limit | - | |
| High-high limit | A Hi high limit res | |
| Low-low limit | - | |
| Residual voltage measurement (RESVMMXU) | High limit | V high limit res |
| Low limit | - | |
| High-high limit | V Hi high limit res | |
| Low-low limit | - | |
| Sequence current measurement (CSMSQI) | High limit | Ps Seq A high limit, Ng Seq A high limit, Zro A high limit |
| Low limit | Ps Seq A low limit, Ng Seq A low limit, Zro A low limit | |
| High-high limit | Ps Seq A Hi high Lim, Ng Seq A Hi high Lim, Zro A Hi high Lim | |
| Low-low limit | Ps Seq A low low Lim, Ng Seq A low low Lim, Zro A low low Lim | |
| Phase sequence voltage measurement (VSMSQI) | High limit | Ps Seq V high limit, Ng Seq V high limit, Zro V high limit |
| Low limit | Ps Seq V low limit, Ng Seq V low limit, Zro V low limit | |
| High-high limit | Ps Seq V Hi high Lim, Ng Seq V Hi high Lim, Zro V Hi high Lim | |
| Low-low limit | Ps Seq V low low Lim, Ng Seq V low low Lim | |
| Three-phase power and energy measurement (PEMMXU) | High limit | - |
| Low limit | - | |
| High-high limit | - | |
| Low-low limit | - | |
Deadband supervision
The deadband supervision function reports the measured value according to integrated changes over a time period. In Figure 2 the values are reported at points Y1, Y2, Y3 and Y4. There is no value report at the end of |A3 + A4 + A5 + A6 + A7| because the positive and negative areas counteract each other. The integrated changes, |A3 + A4 + A5 + A6 + A7|, equal approximately zero.
The deadband value used in the integral calculation is configured with the X deadband setting. The value represents the percentage of the difference between the maximum and minimum limit in the units of 0.001 percent x seconds.
Example for CMMXU:
A deadband = 2500 (2.5 % of the total measuring range of 40)
I_INST_A = I_DB_A = 0.30
If I_INST_A changes to 0.40, the reporting delay is:
|
Function |
Settings |
Maximum/minimum (=range) |
|---|---|---|
|
Three-phase current measurement (CMMXU) |
A deadband |
40/0 (=40xIn) |
|
Three-phase voltage measurement (VMMXU) |
V Deadband |
4/0 (=4xUn) |
|
Residual current measurement (RESCMMXU) |
A deadband res |
40/0 (=40xIn) |
|
Residual voltage measurement (RESVMMXU) |
V deadband res |
4/0 (=4xUn) |
|
Sequence current measurement (CSMSQI) |
Ps Seq A deadband, Ng Seq A deadband, Zro A deadband |
40/0 (=40xIn) |
| Frequency measurement (FMMXU) | F deadband | 0.04/40 |
Power and energy calculation
The three-phase power is calculated from the selected voltage and current measurements as described in Table 4. The setting Measurement mode determines which voltage and current measurements are used.
It is also possible to use positive-sequence components for calculating the apparent power, which makes the determination of power insensitive to any asymmetry in currents or voltages.
| Measurement mode setting values | Power calculation |
|---|---|
| PhsA, PhsB, PhsC |
|
| Arone |
|
| Pos Seq |
|
| PhsAB |
|
| PhsBC |
|
| PhsCA |
|
| PhsA |
|
| PhsB |
|
| PhsC |
|
Depending upon the set Measurement mode, the Power and energy calculation module calculates active power, reactive power and apparent power values from the available set of measurements.
The calculated powers are available as function outputs S_INST, P_INST, Q_INST and the power factor angle as PF_INST.
Depending on the unit multiplier selected with Power unit Mult, the calculated power values in the monitored data and measurement view are presented in units of kVA/kW/kVAr or in units of MVA/MW/MVAr.
| Quadrant | Current | P | Q | PF | Power |
|---|---|---|---|---|---|
| Q1 | Lagging | + | + | 0…+1.00 | +ind |
| Q2 | Lagging | - | + | 0…-1.00 | -cap |
| Q3 | Leading | - | - | 0…-1.00 | -ind |
| Q4 | Leading | + | - | 0…+1.00 | +cap |
The active power P direction can be selected between forward and reverse with Active power Dir and correspondingly the reactive power Q direction can be selected with Reactive power Dir. This affects also the accumulated energy directions.
The accumulated energy is calculated separately as forward active ( EA_FWD_ACM), reverse active ( EA_RV_ACM), forward reactive ( ER_FWD_ACM) and reverse reactive ( ER_RV_ACM). Depending on the value of the unit multiplier selected with Energy unit Mult, the calculated power values are presented in units of kWh/kVArh or in units of MWh/MVArh.
When the energy counter reaches its defined maximum value, the counter value is reset and restarted from zero. Changing the value of the Energy unit Mult setting resets the accumulated energy values to the initial values, that is, EA_FWD_ACM to Forward Wh Initial, EA_RV_ACM to Reverse Wh Initial, ER_FWD_ACM to Forward VArh Initial and ER_RV_ACM to Reverse VArh Initial. It is also possible to reset the accumulated energy to initial values through a parameter or with the RSTACM input.
Sequence components
The phase-sequence components are calculated using the phase currents and phase voltages. More information on calculating the phase-sequence components can be found in Calculated measurements in this manual.