Eaton Cutler-Hammer IQ DP-4000 Installation, Operation And Maintenance Instructions page 35

IQ DP-4000
SECTION 5 - PROGRA M M I N G THE IQ DP-4000
Reset Threshold
Reset Threshold - 0 to 100%
Reset Threshold
Figure 5.2 Undervoltage Detection and Reset Levels
Example 1
A system has the following settings:
Nominal AC Line Voltage = 208 V
Undervoltage Detection Level = 80%
Reset Threshold
For this system : An u ndervoltage alarm will occur at
X
208V 80% = 1 66V
The undervoltage alarm will reset at
1 66V + 75%
= 1 66V + 75%
= 1 66V + 32V = 1 98V
In this example, the undervoltage alarm will not reset
system voltage is above 1 98V.
until the
Example 2
A system has the following settings:
Nominal AC Line Voltage
Undervoltage Detection Level
Determ i ne the reset
undervoltage alarm to
undervoltage alarm occurs at:
X
75%
480V
420V = 360V + RST% x (480V - 360V)
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i
=
0%
=
100%
75%
=
X
(208V - 1 66V)
X
(42V)
480 V
=
75%
=
threshold setting for
reset above 420 V. The
360 V
=
· • / ·
•·•·•
..
420V
RST% x (1 20V) = 420V - 360V = 60V
RST%
In this case, set the reset threshold to 50% .
5.12. 15. 3 Voltage Phase Unbalance Reset Threshold
A voltage phase unbalance occurs when the maximum
voltage deviation between two phases is g reater than a
percentage of the nominal AC line voltage. To find the
voltage level,
unbalance alarm will occur. To do this, multiply the
nominal AC line voltage (see Section 5.5) by the voltage
phase unbalance detection level (see Section 5 . 1 2 . 1 4) .
The reset voltage i s a percentage of the difference ( 1 00
to O%) between zero volts (all of the phases being equal
in voltage) and the voltage phase unbalance detection
level, as determined by the reset threshold. Compute
this by:
VPU MVD - MVD x RST
=
where
VPU = Voltage Phase Unbalance Reset (Volts)
MVD = Maximum Voltage Deviation where a
the
Phase
RST = Reset Threshold
Figure 5.3 illustrates the voltage phase unbalance
detection and reset levels.
TD1 7548A
Nominal Line-to-Line Voltage (Volts)
=
Reset Threshold 50%
Undervoltage Detection Level (Volts)
360V + RST% x (1 20V)
=
I
60V 1 20V = 0.50
=
calculate where a voltage
Unbalance Alarm occurs (Volts)
phase