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 v4
Measuring functions CVMMXN, CMMXU, VMMXU and VNMMXU have no
interconnections regarding any settings or parameters.
Zero clampings are also handled entirely by ZeroDb separately for each function's
every output signal. For example, zero clamping of U12 is handled by
UL12ZeroDb in VMMXU, zero clamping of I1 is handled by IL1ZeroDb in
CMMXU, and so on.
Example of CVMMXN operation
Outputs seen on the local HMI under Main menu/Measurements/Monitoring/
Servicevalues(P_Q)/CVMMXN(P_Q):
S
Apparent three-phase power
P Active three-phase power
Q Reactive three-phase power
PF Power factor
ILAG I lagging U
ILEAD I leading U
U System mean voltage, calculated according to selected mode
I System mean current, calculated according to selected mode
F Frequency
Relevant settings and their values on the local HMI under Main menu/
Settings/IED settings/Monitoring/Servicevalues(P_Q)/CVMMXN(P_Q):
• When system voltage falls below UGenZeroDB, values for S, P, Q, PF, ILAG,
ILEAD, U and F are forced to zero.
• When system current falls below IGenZeroDB, values for S, P, Q, PF, ILAG,
ILEAD, U and F are forced to zero.
• When the value of a single signal falls below its set deadband, the value is
forced to zero. For example, if the apparent three-phase power falls below
SZeroDb, the value for S is forced to zero.
1MRK 504 169-UEN A Section 13
Monitoring
Transformer protection RET650 2.2 IEC 269
Application manual
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