Connection
CAUTION
Settings of connections shall reflect actual state otherwise measurements could not be valid.
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MC784
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MC320, MC330
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MC350
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Connection mode
When connection is selected, load connection and the supported measurements are defined.
Setting of current and voltage ratios
Before setting current and voltage ratios it is necessary to be familiar with the conditions in which device will
be used. All other measurements and calculations depend on these settings. Up to five decimal places can be
set (up / down). To set decimal point and prefix (up / down) position the cursor (left /right) to last (empty)
place or the decimal point.
Aux CT transformer ratios can be set separately from phase CT ratios since Aux CT could differ from phase CTs.
Range of CT and VT ratios:
Settings range
VT primary
VT secondary
CT, Aux CT
primary
CT, Aux CT
secondary
Max value
1638,3 kV
13383 V
1638,3 kA
13383 A
Min value
0,1 V
1 mV
0,1 A
1 mA
Setting of current and voltage ratios : Primary voltage (V), Secondary voltage (V), Primary current
(A), Secondary current (A)
Before setting current and voltage ratios it is necessary to be familiar with the conditions in which device will
be used. All other measurements and calculations depend on these settings. Up to five decimal places can be
set (up / down). To set decimal point and prefix (up / down) position the cursor (left /right) to last (empty)
place or the decimal point.
Settings range
VT primary
VT secondary
CT, Aux CT
primary
CT, Aux CT
secondary
Max value
1638,3 kV
13383 V
1638,3 kA
13383 A
Min value
0,1 V
1 mV
0,1 A
1 mA
Neutral line Primary/Secondary current (A)
Primary /Secondary current of neutral line current transformer.
Used voltage/current range (V/A)
Setting of the range is connected with all settings of alarms, analogue outputs and a display (calculation) of
energy and measurements recording, where 100% represents 500 V. In case of subsequent change of the
range, alarms settings shall be correspondingly changed, as well.
CAUTION
In case of subsequent change of those ranges shall be alarm and analogue output settings correspondingly
changed as well.
Already recorded values will not be valid after change of used voltage and current range!
Frequency nominal value (Hz)
Nominal frequency range can be selected from a set of predefined values. A valid frequency measurement is
within the range of nominal frequency ±32 Hz.
This setting is used for alarms and recorders only.
Max. demand current for TDD (A)
Select maximum current (CT or fuse rating) at a point of instrument connection for proper TDD calculation. TDD
is unlike THD a measure of harmonics relative to fixed value of max. demand current. Therefore TDD is a
demand independent measure of current harmonics.
Wrong connection warning
If all phase currents (active powers) do not have same sign (some are positive and some negative) and/or if
phase voltages and phase currents are mixed, the warning will be activated if this setting is set to YES. This
warning is seen only on remote display.
Energy flow direction
This setting allows manual change of energy flow direction (IMPORT to EXPORT or vice versa) in readings tab. It
has no influence on readings sent to communication or to memory.
CT connection
If this setting is set to REVERSED it has the same influence as if CT’s would be reversely connected. All power
readings will also change its sign.
This setting is useful to correct wrong CT connections.
LCD navigation MC784
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Measurements
General
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
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14.5.2015
16:53:36
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 Main menu
Main menu > Settings > Connection > Connection mode
Main menu > Settings > Connection > VT primary/VT secondary/CT primary/CT secondary