IQ DP-4000
SECTION 5 - PROGRAMMING THE IQ DP-4000
TD 17548B
32
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 = 75%
For this system: An undervoltage alarm will occur at
208V x 80% = 166V
The undervoltage alarm will reset at
166V + 75% x (208V - 166V)
= 166V + 75% x (42V)
= 166V + 32V = 198V
In this example, the undervoltage alarm will not reset
until the system voltage is above 198V.
Example 2
A system has the following settings:
Nominal AC Line Voltage = 480 V
Undervoltage Detection Level = 75%
Determine the reset threshold setting for the
undervoltage alarm to reset above 420 V. The
undervoltage alarm occurs at:
480V x 75% = 360 V
420V = 360V + RST% x (480V - 360V)
420V = 360V + RST% x (120V)
RST% x (120V) = 420V - 360V = 60V
RST% = 60V / 120V = 0.50
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 greater than a
percentage of the nominal AC line voltage. To find the
voltage level, calculate where a voltage phase
unbalance alarm will occur. To do this, multiply the
nominal AC line voltage (see Section 5.5 p.23) by the
voltage phase unbalance detection level (see Section
5.12.14 p.29).
The reset voltage is a percentage of the difference (100
to 0%) 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
Phase
Unbalance Alarm occurs (Volts)
RST = Reset Threshold
On the following page, Figure 5.3 illustrates the voltage
phase unbalance detection and reset levels.
Undervoltage Reset
Zone for Reset
Threshold = 50%
Undervoltage Trip Zone
Reset Threshold = 0%
Reset Threshold - 0 to 100%
Reset Threshold = 100%
Nominal Line-to-Line Voltage (Volts)
Reset Threshold = 50%
Undervoltage Detection Level (Volts)
Undervoltage Reset
Zone for Reset
Threshold = 100%
Summary of Contents for Cutler-Hammer IQ DP-4000
Page 2: ......
