2–16
M-3520 Instruction Book
27 #1 PICKUP
________ Volts
27 #1 DELAY
________ Cycles
27 #2 PICKUP
________ Volts
27 #2 DELAY
________ Cycles
27 Undervoltage, 3 Phase
Voltage is commonly suggested as an efficient
means to protect against islanding. Notably, unless
the DG includes very high-speed generator
excitation response, the island case where load is
greater than generation will result in a rapid drop of
voltage. Except for those systems prone to
ferroresonance, the voltage waveform will remain
Save
Cancel
@ : WARNING, Function DISABLED until output selected!
(27) - UNDERVOLTAGE
Pickup:
Delay:
5 V
1 Cycle
180 V
8160 Cycles
#1
OUTPUT
8
7
6
5
4
3
2
1
FL
6
5
4
3
2
1
Blocking Input
@
Pickup:
Delay:
5 V
1 Cycle
180 V
8160 Cycles
#2
OUTPUT
8
7
6
5
4
3
2
1
FL
6
5
4
3
2
1
Blocking Input
@
Figure 2-9
M-3822 IPScom
®
for Windows™ Undervoltage (27) Setpoint Ranges
Path
: Relay Menu/Setup/Setpoints/(27) Undervoltage
COMMAND BUTTONS
Save
Saves all information to the relay.
Cancel
Returns the user to the previous window; any changes to the displayed information are lost.
Relay volts are equal to the primary bus voltage divided by
the VT ratio.
The operating time of the function.
essentially sinusoidal, making the use of rms value
of fundamental frequency component as the
measurement for this function. An IEEE suggestion
is that undervoltage relays be set at 90% to 95% of
nominal voltage (in accordance with the lower limit
allowed for supply to customers) with a 1 second
time delay to prevent incorrect operation from a
voltage dip caused by an external fault.
If this function is enabled, the following settings are applicable:
Summary of Contents for M-3520
Page 1: ...Instruction Book M 3520 Intertie Protection Relay ...
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