CET Electric Technology
61
4.3.3
Unbalance and Sequence Components
The iMeter 6 provides Voltage and Current Unbalance measurements. The calculation method of U2/U0 and
I2/I0 Unbalances are listed below:
𝑈2 𝑈𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 =
100%
V1
V2
𝐼2 𝑈𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 =
100%
I1
I2
𝐼0 𝑈𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 =
100%
V1
V0
𝐼2 𝑈𝑛𝑏𝑎𝑙𝑎𝑛𝑐𝑒 =
100%
I1
I0
where
V1, V2, V0 are the Positive, Negative Sequence and Zero Components for Voltage, respectively, and
I1, I2, I0 are the Positive, Negative and Zero Sequence Components for Current, respectively.
4.3.4
Deviation
As per Section 5.12 of IEC 61000-4-30:
The 10/12-cycle RMS value Urms can be used to assess the underdeviation and overdeviation parameters in percent of Udin. Th e
underdeviation U
under
and overdeviation U
over
parameters are determined by the following equations.
Voltage Overdeviation (%)
U
over
= 0
if
U
rms
<
U
din
U
over
= ((
U
rms
-
U
din
) /
U
din
) x 100%
if
U
rms
≥
U
din
Voltage Underdeviation (%)
U
under
= 0
if
U
rms
>
U
din
U
under
= ((
U
din
-
U
rms
) /
U
din
) x 100%
if
U
rms
≤
U
din
For
Freq. Deviation
, the
calculation method is listed below:
Freq. Deviation
= ((F - F
nominal
)/F
nominal
) x 100%
where
F
nominal
is the Nominal Frequency
4.3.5
Supply Voltage Dips/Swells and Interruptions
The iMeter 6 supports the detection of
Supply Voltage Dips/Swells
and
Interruptions
using a method that is in
accordance with
IEC 61000-4-30
for Class S performance.
The iMeter 6 provides Dip/Swell and Interruption for voltage quality monitoring on a per phase basis based on
½-cycle
and records any detected event in the
PQ Log
with timestamp and event type. Further, the Dip/Swell
and Interruption Detection can be programmed to trigger WFR, DR, DO and Alarm Email. The programming of
the Dip/Swell and Interruption
setpoint parameters is supported via the Web Interface or communications.
Parameter
Description
Options/Value, Default*
Enable
Dip/Swell/Interruption Detection Enable
Enable* / Disable
Dip Threshold
Specify the Dip threshold of voltage
1% to 99% (xUllnominal), 90%*
Dip Hysteresis
Specify the Dip return threshold of voltage
0.1% to 100% (×Ullnominal), 0.5%*
Swell Threshold
Specify the Swell threshold of voltage
101% to 200% (×Ullnominal), 110%*
Swell Hysteresis
Specify the Swell return threshold of voltage
0.1% to 100% (×Ullnominal), 0.5%*
Interruption Threshold
Specify the Interruption threshold of voltage
0% to 50% (xUllnominal), 10%*
Interruption Hysteresis
Specify the Interruption return threshold of voltage
0.1% to 100% (×Ullnominal), 0.5%*
Trigger 1
Specify the action taken when the Dip/Swell/Interruption setpoint actives
DOx/DRx/HS DRx/WFRx/SMTP, WFR2*
Trigger 2
Specify the action taken when the Dip/Swell/Interruption setpoint actives
DOx/DRx/HS DRx/WFRx/SMTP, N/A*
Table 4-8 Dip/Swell/Interruption Setup Parameters
For the Dip/Swell and Interruption detection to work correctly, it’s critically important to set the
Ull
nominal
parameter correctly with the nominal line-to-line voltage on the secondary (meter) side.
