GE N60 Instruction Manual page 142

PRODUCT SETUP
DEFAULT MESSAGE TIMEOUT
message. The inactivity time is modified using this setting to ensure that messages remain on the screen long enough
during programming or reading of actual values.
DEFAULT MESSAGE INTENSITY
attenuated during default message display. During keypad interrogation, the display always operates at full brightness.
SCREEN SAVER FEATURE
(LCD) and control its backlighting. When the
DEFAULT MESSAGE TIMEOUT
target messages are active. When a keypress occurs or a target becomes active, the LCD backlighting turns on.
CURRENT CUT-OFF LEVEL
are very susceptible to noise. Some customers prefer very low currents to display as zero, while others prefer the current to
display even when the value reflects noise rather than the actual signal. The N60 applies a cut-off value to the magnitudes
and angles of the measured currents. If the magnitude is below the cut-off level, it is substituted with zero. This applies to
phase and ground current phasors as well as true RMS values and symmetrical components. The cut-off operation applies
to quantities used for metering, protection, and control, as well as those used by communications protocols. Note that the
cut-off level for the sensitive ground input is 10 times lower that the
samples available via oscillography are not subject to cut-off.
VOLTAGE CUT-OFF LEVEL
(at the fractional volt level) can be affected by noise. Some customers prefer these low voltages to be displayed as zero,
while others prefer the voltage to be displayed even when the value reflects noise rather than the actual signal. The N60
applies a cut-off value to the magnitudes and angles of the measured voltages. If the magnitude is below the cut-off level,
it is substituted with zero. This operation applies to phase and auxiliary voltages, and symmetrical components. The cut-off
operation applies to quantities used for metering, protection, and control, as well as those used by communications
protocols. Raw samples of the voltages available via oscillography are not subject to cut-off.
5
The
CURRENT CUT-OFF LEVEL
power cut-off level is calculated using the following equations. For Delta connections:
3-phase power cut-off
For Wye connections:
3-phase power cut-off
per-phase power cut-off
where VT primary = VT secondary  VT ratio and CT primary = CT secondary  CT ratio.
For example, given the following settings:
CURRENT CUT-OFF LEVEL
VOLTAGE CUT-OFF LEVEL
PHASE CT PRIMARY
PHASE VT SECONDARY
PHASE VT RATIO
PHASE VT CONNECTION
We have:
CT primary = "100 A", and
VT primary =
PHASE VT SECONDARY
The power cut-off is therefore:
power cut-off= (
 0.02 pu  1.0 V  100 A  13811.2 V) / 66.4 V
= (
3
= 720.5 watts
Any calculated power value below this cut-off does not display. As well, the three-phase energy data do not accumulate if
the total power from all three phases does not exceed the power cut-off.
5-26
— If the keypad is inactive for a period of time, the relay automatically reverts to a default
— To extend phosphor life in the vacuum fluorescent display, the brightness can be
and
SCREEN SAVER WAIT TIME
SCREEN SAVER FEATURE
followed by the
SCREEN SAVER WAIT TIME
— This setting modifies the current cut-off threshold. Very low currents (1 to 2% of the rated value)
— This setting modifies the voltage cut-off threshold. Very low secondary voltage measurements
and the
VOLTAGE CUT-OFF LEVEL

3
CURRENT CUT-OFF LEVEL
= ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -

3
CURRENT CUT-OFF LEVEL
= --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
CURRENT CUT-OFF LEVEL
= ------------------------------------------------------------------------------------------------------------------------------------------------------------------------- -
: "0.02 pu"
: "1.0 V"
: "100 A"
: "66.4 V"
: "208.00 : 1"
: "Delta"
x
PHASE VT RATIO

CURRENT CUT-OFF LEVEL OLTAGE CUT-OFF LEVEL
V
N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
— These settings are only visible if the N60 has a liquid crystal display
is "Enabled," the LCD backlighting turns off after the
, provided that no keys have been pressed and no
CURRENT CUT-OFF LEVEL
are used to determine the metered power cut-off levels. The

VOLTAGE CUT-OFF LEVEL
VT secondary

VOLTAGE CUT-OFF LEVEL
VT secondary
 
VOLTAGE CUT-OFF LEVEL
VT secondary
= 66.4 V x 208 = 13811.2 V
 CT primary  VT primary)/VT secondary
CHAPTER 5: SETTINGS
setting value. Raw current
 
VT primary CT primary
 
VT primary CT primary

VT primary CT primary
Eq. 5-3
Eq. 5-4
Eq. 5-5