Hitachi Relion 670 Series Applications Manual page 350

Section 15
Monitoring
MaxLoadCurr: Maximum demand load current at PCC for total demand distortion calculation. When
the point of common coupling (PCC) is considered at the service entrance or utility metering point,
IEEE 519-2014 standard recommends that the maximum demand load current must be calculated as
the average current of the maximum demand for the preceding 12 months.
WrnLimitTDD: It defines the warning limit for the calculated total demand distortion. The difference
between THD and TDD is helpful to find the harmonics level during light load conditions. According to
standard IEEE 519-2014, harmonic current distortions on a power system with short circuit strength
less than 20 is limited to 5% total demand distortion (TDD).
tDelayAlmTDD: It defines the alarm time limit for the calculated total demand distortion which is
applied after the warning signal pickup and depends on its sustainability.
WrnLimitTHD: It defines the warning limit for the calculated total harmonic distortion.
tDelayAlmTHD: It defines the alarm time limit for the calculated total harmonic distortion which is
applied after the warning signal pickup and depends on its sustainability. This intimates the operator
to take corrective operations immediately, otherwise the system will go under thermal stress.
WrnLimit2ndHD: It defines the warning limit for the calculated second harmonic distortion.
tDelayAlm2ndHD: It defines the alarm time limit for the calculated second harmonic distortion which
is applied after the warning signal pickup and depends on its sustainability.
WrnLimit3rdHD: It defines the warning limit for the calculated third harmonic distortion.
tDelayAlm3rdHD: It defines the alarm time limit for the calculated third harmonic distortion which is
applied after the warning signal pickup and depends on its sustainability.
WrnLimit4thHD: It defines the warning limit for the calculated fourth harmonic distortion.
tDelayAlm4thHD: It defines the alarm time limit for the calculated fourth harmonic distortion which is
applied after the warning signal pickup and depends on its sustainability.
WrnLimit5thHD: It defines the warning limit for the calculated fifth harmonic distortion.
tDelayAlm5thHD: It defines the alarm time limit for the calculated fifth harmonic distortion which is
applied after the warning signal pickup and depends on its sustainability.
WrnLimit6thHD: It defines the warning limit for the calculated sixth harmonic distortion.
tDelayAlm6thHD: It defines the alarm time limit for the calculated sixth harmonic distortion which is
applied after the warning signal pickup and depends on its sustainability.
WrnLimit7thHD: It defines the warning limit for the calculated seventh harmonic distortion.
tDelayAlm7thHD: It defines the alarm time limit for the calculated seventh harmonic distortion which
is applied after the warning signal pickup and depends on its sustainability.
WrnLimit8thHD: It defines the warning limit for the calculated eighth harmonic distortion.
tDelayAlm8thHD: It defines the alarm time limit for the calculated eighth harmonic distortion which is
applied after the warning signal pickup and depends on its sustainability.
WrnLimit9thHD: It defines the warning limit for the calculated ninth harmonic distortion.
344
Minimum and maximum current limit is set as 5% of the IB and 300.0% of IB respectively.
If the current is outside the above range, the calculation of total harmonic distortion,
individual harmonic distortion, total demand distortion and crest factor are blocked, and
outputs are provided as zero.
© 2017 - 2023 Hitachi Energy. All rights reserved
1MRK506375-UEN Rev. N
Railway application RER670
Application manual